Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Bow rigger?
1,776 views
Skip to first unread message
RobP
Feb 19, 2010, 4:15:32 AM2/19/10
to
Any ideas on why this Empacher design (wing-rigger mounted in the bow
behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
thought to confer an advantage? Looks to me like the rigger would be
longer and more complex in shape (and so possibly heavier) than a
standard wing rigger. I note that the lady in the picture looks
faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
left over from last year?
behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
thought to confer an advantage? Looks to me like the rigger would be
longer and more complex in shape (and so possibly heavier) than a
standard wing rigger. I note that the lady in the picture looks
faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
left over from last year?
Rob
RobP
Feb 19, 2010, 4:19:39 AM2/19/10
to
Just noticed that the link above doesn't take you all the way to the
picture. At the bottom of the page opened by the link is a link to
"Details" for "Boat type / rigger versions - V - aluminium bow wing
rigger". Click on that.
R
Carl Douglas
Feb 19, 2010, 6:28:17 AM2/19/10
to
RobP wrote:
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage?
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage?
Simple. It doesn't.
But Fluidesign did it. Then Filippi did it. So Empacher have done it.
And that's how it goes.
Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
Rowers like to imagine that aligning the stay that way will somehow help
to push the boat forwards. It doesn't.
A previous myth had it that a stern-mounted wing rigger must be more
efficient than other types because, the notion went, it made a more
direct connection between the pin & the feet. In which case the
bow-mounted rigger is a painful inversion of that prior bogus logic
since it interposes the maximum amount of boat between feet & rigger, &
the longest possible rigger stay into the bargain. Ho hum...
The sad reality is that these are just costly fashion & style fads
bobbing about in a science-free zone, with boat-builders pandering to
each latest whim.
I guess this could take us straight into another thread on Myths in Rowing.
Cheers -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: http://tinyurl.com/2tqujf
Email: ca...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)
mruscoe
Feb 19, 2010, 6:57:57 AM2/19/10
to
On 19/02/2010 11:28, Carl Douglas wrote:
> Rowers like to imagine that aligning the stay that way will somehow help
> to push the boat forwards. It doesn't.
>
> A previous myth had it that a stern-mounted wing rigger must be more
> efficient than other types because, the notion went, it made a more
> direct connection between the pin & the feet. In which case the
> bow-mounted rigger is a painful inversion of that prior bogus logic
> since it interposes the maximum amount of boat between feet & rigger, &
> the longest possible rigger stay into the bargain. Ho hum...
>
> The sad reality is that these are just costly fashion & style fads
> bobbing about in a science-free zone, with boat-builders pandering to
> each latest whim.
> Rowers like to imagine that aligning the stay that way will somehow help
> to push the boat forwards. It doesn't.
>
> A previous myth had it that a stern-mounted wing rigger must be more
> efficient than other types because, the notion went, it made a more
> direct connection between the pin & the feet. In which case the
> bow-mounted rigger is a painful inversion of that prior bogus logic
> since it interposes the maximum amount of boat between feet & rigger, &
> the longest possible rigger stay into the bargain. Ho hum...
>
> The sad reality is that these are just costly fashion & style fads
> bobbing about in a science-free zone, with boat-builders pandering to
> each latest whim.
I don't disagree about the existence of pseudo-scientific fads in
equipment design, but there is apparently something about the feel of
bow-mounted riggers (both wing and carbon a-frame) that some athletes
like. Providing that they are not kidding themselves when trying a piece
of different equipment, the reaction of pin pitch under load through the
stroke seems one possible difference.
Alexander Lindsay
Feb 19, 2010, 7:39:44 AM2/19/10
to
Scratchung around for some rationale for such a design, might it be argued
that this design is safer, in that, in a collision with another boat, the
rigger presents a sloping face to the other crew? Having been involved in
several collisions over the last 60 years, and having survived all
relatively safely, the two things that really worry me are being hit in the
back by the bows of a boat or by a "normal" wing rigger.
that this design is safer, in that, in a collision with another boat, the
rigger presents a sloping face to the other crew? Having been involved in
several collisions over the last 60 years, and having survived all
relatively safely, the two things that really worry me are being hit in the
back by the bows of a boat or by a "normal" wing rigger.
But I don't suggest this as any justification of any sort of wing rigger.
Alexander Lindsay
"Carl Douglas" <ca...@carldouglas.co.uk> wrote in message
news:7u7auk...@mid.individual.net...
Carl Douglas
Feb 19, 2010, 7:55:36 AM2/19/10
to
Pin pitch change under load depends on rigger stiffness, pin diameter &
the vertical distance of centre of load from shoulder of pin.
What you feel as a user depends on what you're comparing with & what you
have been told, whereas actual measurement gives hard numbers. So, if
what you've used previously was any one of a number of notorious makes
of torsionally-flexible riggers, some wings will really be stiffer in
torsion while others most definitely will not. If you compare with the
stiffest conventional riggers in the business, then you will find no
improvement. But if you believe it must be better - the placebo effect
- you will still find them better.
The current fashion for 13mm sweep pins is an interesting case of
engineering logic going straight out of the window. With a
well-designed rigger, much of any change in pitch under load is due to
pin deflexion. Pin deflexion is proportional to the inverse cube of pin
diameter. So opting for a 13mm diameter pin over one of the traditional
9/16" diameter increases pin flex under load by 1/3.
There's always a strong desire, & pressure, to believe what we're told &
not to question too much. Best not let ourselves be confused by
introducing too many inconvenient facts.
;)
Christopher Anton
Feb 19, 2010, 1:04:38 PM2/19/10
to
"RobP" <R...@Purwell.Net> wrote in message
news:df7a6215-11eb-40fd...@q21g2000yqm.googlegroups.com...
On 19 Feb, 09:15, RobP <R...@Purwell.Net> wrote:
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler)http://www.empacher.com/rennboote/Einer_e.htmlis
> thought to confer an advantage? Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
Well the boat couldn't weigh any less, whatever the weight of the rigger,
according to the rules
Walter Martindale
Feb 19, 2010, 1:31:06 PM2/19/10
to
As Carl has mentioned, a few other builders have put this type of
rigger on their boat. The first I was aware of was Bruce Lodder
"Pieces of Eight" boats made in NZ back in the 90s. He got out of the
boat building when Chinese boats started up. Then fluiddesign, and
others started up. Bruce's boats (up to 4+) had carbon wing bow-
mounted riggers.
The lady in the picture looks a lot like the Kiwi rep single sculler
of the last few years. Probably a boat used for a post-season Europe
tour competition, and "Ok, take my picture, but I'm getting ready to
race" or "Ok, but I'm tired, I just finished a race." or something
similar may be in her thoughts.
Walter
Henning Lippke
Feb 19, 2010, 5:40:55 PM2/19/10
to
Am 19.02.2010 10:15, schrieb RobP:
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage?
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage?
I guess Fluidesign is taking too much market share.
Here's some more:
http://www.empacher.com/News/news_e_1.html
Sarah A Harbour
Feb 20, 2010, 4:27:19 PM2/20/10
to
>
> But Fluidesign did it. Then Filippi did it. So Empacher have done it.
> And that's how it goes.
>
Yes, I tried a friends' Fluidesign with a wing rigger like that and I
didn't like it. I made me feel really *naked* at the catch with no
frontstay underneath the oar looms!
Glad I don't have one a bow wing rigger for another reason too - where
would be the space to stick my bottle pocket?! ;)
Sarah
xx
Roger
Feb 24, 2010, 7:51:11 PM2/24/10
to
On Feb 20, 4:27 pm, Sarah A Harbour <sarahaharb...@googlemail.com>
wrote:
wrote:
I'm with Sarah on this one and for none of the technical reasons.
Again a Fluidesign boat that a club member allowed me to paddle around
in, It's an odd feeling with nothing in front of you. I guess it's all
in my head as I was the same when I had back stays on my Aylings, I
felt hemmed in. With the Fluidesign bow mounted rigger I felt like I
was rowing on a tightrope and exposed.
it's all in the mind
Stelph
Feb 25, 2010, 12:30:20 PM2/25/10
to
Filippi have the bow rigger as well,
http://www.filippiboats.it/UserFiles/File/braccio%20ala%20inglese%201.pdf
Seems the general opinion on here is that its down to a rowers
preference, personally when I borrowed a fluidesign for the HOCR it
was a very odd experience to start with as I assume your just aware
that something (i.e. riggers) are missing from your immediate
periphery vision! However quite quickly on in the outing I got used to
it and didn’t think anything more about it after then.
Its probably becoming an option on more and more boats for that age
old reason, because it looks "cool" :)
Gman
Mar 8, 2010, 1:01:09 AM3/8/10
to
the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
boat for an event in Europe.
boat for an event in Europe.
Walter Martindale
Mar 14, 2010, 1:05:47 PM3/14/10
to
On Feb 19, 10:15 pm, RobP <R...@Purwell.Net> wrote:
One possible advantage I've found recently with two people I've
coached... The cross-bar of the 'stern-wing' rigger can, prevent the
foot-stretchers from being far enough aft to position a sculler
correctly with respect to the pins. Shins hit the cross-bar.
Solution for those boats is to replace the rigger with one that
reaches farther bow-ward, but at least with the forward-mounted wing
rigger this isn't a problem.
Walter
Nick M
Mar 19, 2010, 8:11:19 AM3/19/10
to
On 8 Mar, 07:01, Gman <gcra...@gmail.com> wrote:
> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
> boat for an event in Europe.
> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
> boat for an event in Europe.
Indeed it is, and she had just won the Armada Cup in Switzerland for
the second time:
235 entrants all in 1x racing over 9km, a mass start, racing against
Olympians, and a 90 degree turn around a buoy about 750m after the
start make it a pretty memorable race!
Carl Douglas
Mar 19, 2010, 8:19:37 AM3/19/10
to
Sounds like a small-scale re-enactment of that other Armada event, back
around 1588. Do the Dutch help with the fire-ships, or are hostilities
limited to a bit of accidental ramming at the buoy?
;)
StephenA
Mar 19, 2010, 11:51:31 AM3/19/10
to
On Mar 19, 12:19 pm, Carl Douglas <c...@carldouglas.co.uk> wrote:
> Nick M wrote:
> > On 8 Mar, 07:01, Gman <gcra...@gmail.com> wrote:
> >> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
> >> boat for an event in Europe.
>
> > Indeed it is, and she had just won the Armada Cup in Switzerland for
> > the second time:
>
> >http://www.armadacup.ch/
>
> > 235 entrants all in 1x racing over 9km, a mass start, racing against
> > Olympians, and a 90 degree turn around a buoy about 750m after the
> > start make it a pretty memorable race!
>
> Sounds like a small-scale re-enactment of that other Armada event, back
> around 1588. Do the Dutch help with the fire-ships, or are hostilities
> limited to a bit of accidental ramming at the buoy?
> ;)
> Carl
> --
> Carl Douglas Racing Shells -
> Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
> Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
> Find: http://tinyurl.com/2tqujf
> Email: c...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682> Nick M wrote:
> > On 8 Mar, 07:01, Gman <gcra...@gmail.com> wrote:
> >> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
> >> boat for an event in Europe.
>
> > Indeed it is, and she had just won the Armada Cup in Switzerland for
> > the second time:
>
> >http://www.armadacup.ch/
>
> > 235 entrants all in 1x racing over 9km, a mass start, racing against
> > Olympians, and a 90 degree turn around a buoy about 750m after the
> > start make it a pretty memorable race!
>
> Sounds like a small-scale re-enactment of that other Armada event, back
> around 1588. Do the Dutch help with the fire-ships, or are hostilities
> limited to a bit of accidental ramming at the buoy?
> ;)
> Carl
> --
> Carl Douglas Racing Shells -
> Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
> Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
> Find: http://tinyurl.com/2tqujf
> URLs: www.carldouglas.co.uk(boats) &www.aerowing.co.uk(riggers)
One of the problems with rear wing riggers is they may get in the way
of the stretcher: make it difficult to adjust the stretcher or even
stop the feet being raised. The front wing leaves the stretcher clear
again. and it might be a tiny bit more aerodynamic in a severe
headwind.
Stephen
Mike De Petris
Mar 19, 2010, 3:14:44 PM3/19/10
to
On Mar 19, 4:51 pm, StephenA <stephen.ait...@theStrateg-e.com> wrote:
> One of the problems with rear wing riggers is they may get in the way
> of the stretcher: make it difficult to adjust the stretcher or even
> stop the feet being raised. The front wing leaves the stretcher clear
> again. and it might be a tiny bit more aerodynamic in a severe
> headwind.
> One of the problems with rear wing riggers is they may get in the way
> of the stretcher: make it difficult to adjust the stretcher or even
> stop the feet being raised. The front wing leaves the stretcher clear
> again. and it might be a tiny bit more aerodynamic in a severe
> headwind.
Are you swapping front and rear?
Your words make sense if I take front=bow and rear=stern, where I had
used the opposite for front and rear, like in frontstops for example.
Carl Douglas
Mar 19, 2010, 9:01:18 PM3/19/10
to
StephenA wrote:
> On Mar 19, 12:19 pm, Carl Douglas <c...@carldouglas.co.uk> wrote:
>> Nick M wrote:
>>> On 8 Mar, 07:01, Gman <gcra...@gmail.com> wrote:
>>>> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
>>>> boat for an event in Europe.
>>> Indeed it is, and she had just won the Armada Cup in Switzerland for
>>> the second time:
>>> http://www.armadacup.ch/
>>> 235 entrants all in 1x racing over 9km, a mass start, racing against
>>> Olympians, and a 90 degree turn around a buoy about 750m after the
>>> start make it a pretty memorable race!
>> Sounds like a small-scale re-enactment of that other Armada event, back
>> around 1588. Do the Dutch help with the fire-ships, or are hostilities
>> limited to a bit of accidental ramming at the buoy?
>> ;)
>> Carl
> On Mar 19, 12:19 pm, Carl Douglas <c...@carldouglas.co.uk> wrote:
>> Nick M wrote:
>>> On 8 Mar, 07:01, Gman <gcra...@gmail.com> wrote:
>>>> the 'lady' is Emma Twigg the NZ sculler. she must have borrowed the
>>>> boat for an event in Europe.
>>> Indeed it is, and she had just won the Armada Cup in Switzerland for
>>> the second time:
>>> http://www.armadacup.ch/
>>> 235 entrants all in 1x racing over 9km, a mass start, racing against
>>> Olympians, and a 90 degree turn around a buoy about 750m after the
>>> start make it a pretty memorable race!
>> Sounds like a small-scale re-enactment of that other Armada event, back
>> around 1588. Do the Dutch help with the fire-ships, or are hostilities
>> limited to a bit of accidental ramming at the buoy?
>> ;)
>> Carl
>
> One of the problems with rear wing riggers is they may get in the way
> of the stretcher: make it difficult to adjust the stretcher or even
> stop the feet being raised. The front wing leaves the stretcher clear
> again. and it might be a tiny bit more aerodynamic in a severe
> headwind.
>
> Stephen
Neither front-mounted, nor rear-mounted, wings are particularly
aerodynamic since they are rather thick, with not particularly good aero
sections, & carry a lot of surface area. And, if they did have
aerodynamic sections, you'd then suffer markedly on windy days from the
unpredictable aerodynamic forces they'd then generate.
Yes, stern-mounted wings can get in the way of toes & shins. But
there's no reason why front-mounted wings should be any more aerodynamic
in headwind or not - that they angle sternwards does not decrease their
wind drag - sweep-back is only of value to the performance of real wings
when operating at far higher air speeds than I hope any sculler will
ever encounter.
Cheers -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: http://tinyurl.com/2tqujf
John Mulholland
Mar 22, 2010, 7:49:20 PM3/22/10
to
"Carl Douglas" <ca...@carldouglas.co.uk> wrote in message
news:80il32...@mid.individual.net...Carl,
You assured me I could reach transonic speeds in the lovely boat you sold
me! Sadly, I'm still at least 530 m.p.h. short of the lower end of the
transonic region.
--
John Mulholland
Carl Douglas
Mar 22, 2010, 8:24:43 PM3/22/10
to
>
> Carl,
>
> You assured me I could reach transonic speeds in the lovely boat you sold
> me! Sadly, I'm still at least 530 m.p.h. short of the lower end of the
> transonic region.
>
Let's see:
Speed of sound in air = 330 m/s, in water = 1500 m/s. But your boat's
dominant regime is water.
The transonic region lies at Mach 0.8 - 1.2. So in water the transonic
begins at 1200 m/s.
Your claimed 530 mph velocity deficit = 850 m/s in new money.
Deducting 850 from 1200, we see that you're moving your boat at ~350
m/s, giving you a 2k time of a snip under 6 seconds. Yet you have the
temerity to complain!
May I congratulate you, John, on being the first man on the R Tyne, let
alone on water, to achieve M2.6 through the air? Harry Clasper would
have been impressed, had he lived another 140 years. OTOH, RSR's David
Henderson will say, when he reads this, that they went faster when he
wor a lad.
;)
Carl Douglas
Mar 22, 2010, 8:34:01 PM3/22/10
to
Oops! 530mph = 240 m/s. Always check before posting :( So you're
achieving M7, which is truly hypersonic & likely to lead to a hint of
singeing of the hair & elbows. And your 2k time is down to 2 seconds.
What rating are you at?
Lesson: never attempt maths at bed-time, just stick to counting sheep.
John Mulholland
Apr 4, 2010, 8:12:32 AM4/4/10
to
"Carl Douglas" <ca...@carldouglas.co.uk> wrote in message
news:80qgjr...@mid.individual.net...Sorry, Carl, I've been away from RSR for a few days. I'm beginning to
understand why nobody else ever sees me training! I finish the outing just
before I start it.
--
John Mulholland
rb...@cam.ac.uk
Apr 26, 2012, 10:46:03 AM4/26/12
to
This thread is rather old, so I am a little late to the discussion &/or no one might be reading any more, but as a (rowing) (aerospace) engineer, I feel I have to speak up against some of the backward & disappointing attitudes expressed in this thread.
Firstly & fairly trivially - Carl, I think you may have got yourself a little tangled up re transonic speeds, etc. The speed of sound through water is very rarely (if ever) relevant when considering motion though water, so 'transonic speed' almost always pertains to speed through air (& more or less can't be achieved in water without super-cavitating, at which point the speed of sound through water is moot, etc., etc. basically it doesn't matter). The point being I think, that the speed of sound in air is circa 535mph, so John was only managing ~5 mph, I.e. normal speeds in a rowing boat!
More importantly: bow wing riggers. I concede that I haven't done any analysis - my consideration is purely qualitative. It may be in some cases that it turns out that the numbers stack up against my argument, though I doubt it & in some cases this is impossible. Similarly, it is impossible to say conclusively that it will make any & all boats go faster - there are simply too many variables & it is more or less impossible to prove incontrovertibly - the same rower can't test the same boat at the same time (tiredness comes into play if tested consecutively) on exactly the same bit of water, but with different riggers, while any other comparative statements are unlikely to be conclusive. And rowers' preference would play a part. I also can't say that bow wing riggers are being introduced for purely, genuinely performance related reasons. However, this doesn't mean that it can't be ascertained with some certainty that they have advantages.
The argument here & elsewhere, that had it been a good idea, it would have been done a long time before, is both flawed & misguided. The simple fact is that an idea has to be thought of at some point & in some cases it is not possible or maybe not economical for it to happen until something else does, namely developments in materials & manufacturing techniques - there's a reason that reciprocating steam engines were used in the past, but we don't load coal & water into our cars on a weekly/daily basis.
One thing that can be said without ambiguity is that a bow wing arrangement interferes the least with the rower. Arguments about 'feeling naked' are indeed all *purely* in a rower's head. If perception was key, we'd all be rowing with pontoons à la arms only adaptive! (that's not a pop at adaptive rowers, btw, but the simple fact is able bodied rower don't need floats). Once you get used to the feeling, the fact that there are no ribs to catch your hips on, slides which can be made further apart to clear your calves, no riggers or cross stays in & around the feet & no, even vague, possibility of the oar handle/hands catching the rigger (eg. in rough weather), can all be seen as clear advantages.
Another advantage to having all the mountings for the rigger at the 'bow end' of the cockpit is that, as with the entire saxboard of the a conventionally rigged boat & the stern of an stern wing rigged boat, must be built up to support the riggers. In the case of the bow wing, all the build up is at the bow, so any waves braking over the canvas, or rolling up the side of the boat have a better chance of being deflected. I contrast this with the personal experience of a wet backside every time I catch a significant cross-head wind in a stern wing rigged club 1x. Such boats could have the built up saxboards/wave breaker (not certain what the 'front of the cockpit is called??), but this would add weight/serve a single purpose.
Other advantages come down to comparisons between of Wing vs Conventional & Bow vs Stern arrangements.
1st Wing vs Conventional. It may appear that the conventional riggers are more efficient. They are lighter, appear simpler, all forces appear compressive/tensile, right? Wrong. The simple fact is that while this may be almost true of the riggers, it is certainly not true of the ribs in the boat which have to carry loads from one side to the other. These must carry significant bending loads, which offset the simplicity of the riggers. They are heavy & their weight is forced to be evenly distributed along the length of the boat. If bow loading coxed boats are anything to go by, it seams fairly safe to say that having this extra 'rigging' weight in the bow is advantageous, even if (due to FISA rules) the bow wing arrangement can't bring the overall weight down. That being said, if they have the potential to be lighter, the 'spare weight' can be put to better use: general durability, ballast at the bow of the boat (reduces pitching) ballast at the kelson (reduces rolling), aerodynamic fairing, or any number of other uses.
This may all be a bit '6 of one, 1/2 dozen of the other,' but what is certain is that the greatest stress (bending) in a conventional boat is in the ribs. With every stroke, they & the adjacent material flex & gradually becomes less stiff, eventually rendering the boat useless. Conversely, the only axial loads are carried by the hull of a bow wing boat. Distributing the mass of the ribs more evenly can make the hull generally more durable, while the large bending loads are confined to the rigger. Thus, the hull will last, while the (relatively) cheap rigger is left to weaken & be replaced when necessary.
Similarly, by having all the material concentrated in one place, a wing rigger is likely to be/can be made more resistant to impact, certainly compared to top stays. And while (as Carl rightly said) the sweep has no effect on drag, it does mean that if you run into something, it is more likely to get deflected away without damage (compared to conventional/top stay riggers) or snaring something (compared to plain (no top stay) stern wing riggers - if as happens occasionally I manage to run into one of a number of large sailors' buoys strewn around my stretch of water, the stern wing rigger drags them to the side of the boat, along with a fair bit of water into it, & pin it there, making backing out awkward (the buoy ends up in the way of the oar) & painstaking (must go a long way to 'unsnag' myself)).
Also, while sweep has no effect on drag, cross section does. Structurally, the wings of an aircraft would benefit from being wire braced, but no recent aircraft of note have them, because many small elements produce more drag than one big one. Thus, one 'rather thick' rigger is likely to produce less drag than 2, 3 or 4 smaller arms of a conventional rigger. More over, for what ever reason conventional riggers aren't built in aerodynamic sections, while wing riggers are & the notion that they're not aerodynamic is absurd. 'Tear drop' cross sections produce an order of magnitude less drag than circular ones - that is why the aerials, struts, etc. on aircraft are not circular - the E-3 is a classic, substantial example: http://air-boyne.com/boeing-e-3a-awacs-early-warning/ (compare side & head on views of the struts supporting the radome). Lastly, a symmetrical 'aerodynamic shape' aligned to the direction of airflow won't produce any aerodynamic (lifting) force, whereas in certain conditions, a cylinder can: http://www.mecaenterprises.com/vortex_shedding.htm On the other hand, if an aerodynamic section is made to rise & fall (due to rolling), the lift it would generate would actually (albeit very slightly in this case) oppose the rolling!
Bow vs Stern arrangements: By virtue of needing to facilitate rowing through the pin, a stern arrangement (stern wing or 2 stay - '3 stay without the top stay!) can only support the pin from below. While it is quite possible for this arrangement to be very stiff, a bending &/or torsional load is developed: that is unavoidable. Therefore, there will always be *some* pin pitching. The riggers can be stiffened, but this requires the rigger tubes to be thicker &/or wider, & the tendency will never go away. Similarly, a top stay can be added, but this requires yet more weight, and extra rib & the simple fact is that the axis of the top stay doesn't directly oppose the motion of the top of the pin, so some load will always be carried in a non ideal direction. Conversely, in a bow arrangement (bow wing or '2 stay back rigger') it is possible to support the pin symmetrically from above & below. With the 2 stay, since loads must still be carried predominantly in tension/compression, either they must come to a point at the pin (like the swift racing 2 stay back riggers) in which case there is again a risk of the oar striking the rigger, or not (like the Dreher side mounted riggers) in which case some torsion/bending loads will still be developed & in spite of the use of C brackets to support the pins, there will still be some pin pitching/rolling. The only way to avoid this is the bow wing rigger.
The last, maybe tenuous point is that bow wing riggers are easily the most conducive to mounting the pin further back. Any other arrangement either requires extra material or movement of the ribs which can have other effects, were as a bow wing rigger need only be shortened, making it even lighter.
The bottom line is there are many advantages, either intrinsic or potential. They are becoming far more common & as that happens, more of the advantages will be brought to the fore & further refined, so I very much doubt that they will simply go out of fashion. And if they do, it would be a big mistake - comparisons with petrol engines, gas turbines & hybrid cars (on an admittedly different level) spring to mind.
Mike
Firstly & fairly trivially - Carl, I think you may have got yourself a little tangled up re transonic speeds, etc. The speed of sound through water is very rarely (if ever) relevant when considering motion though water, so 'transonic speed' almost always pertains to speed through air (& more or less can't be achieved in water without super-cavitating, at which point the speed of sound through water is moot, etc., etc. basically it doesn't matter). The point being I think, that the speed of sound in air is circa 535mph, so John was only managing ~5 mph, I.e. normal speeds in a rowing boat!
More importantly: bow wing riggers. I concede that I haven't done any analysis - my consideration is purely qualitative. It may be in some cases that it turns out that the numbers stack up against my argument, though I doubt it & in some cases this is impossible. Similarly, it is impossible to say conclusively that it will make any & all boats go faster - there are simply too many variables & it is more or less impossible to prove incontrovertibly - the same rower can't test the same boat at the same time (tiredness comes into play if tested consecutively) on exactly the same bit of water, but with different riggers, while any other comparative statements are unlikely to be conclusive. And rowers' preference would play a part. I also can't say that bow wing riggers are being introduced for purely, genuinely performance related reasons. However, this doesn't mean that it can't be ascertained with some certainty that they have advantages.
The argument here & elsewhere, that had it been a good idea, it would have been done a long time before, is both flawed & misguided. The simple fact is that an idea has to be thought of at some point & in some cases it is not possible or maybe not economical for it to happen until something else does, namely developments in materials & manufacturing techniques - there's a reason that reciprocating steam engines were used in the past, but we don't load coal & water into our cars on a weekly/daily basis.
One thing that can be said without ambiguity is that a bow wing arrangement interferes the least with the rower. Arguments about 'feeling naked' are indeed all *purely* in a rower's head. If perception was key, we'd all be rowing with pontoons à la arms only adaptive! (that's not a pop at adaptive rowers, btw, but the simple fact is able bodied rower don't need floats). Once you get used to the feeling, the fact that there are no ribs to catch your hips on, slides which can be made further apart to clear your calves, no riggers or cross stays in & around the feet & no, even vague, possibility of the oar handle/hands catching the rigger (eg. in rough weather), can all be seen as clear advantages.
Another advantage to having all the mountings for the rigger at the 'bow end' of the cockpit is that, as with the entire saxboard of the a conventionally rigged boat & the stern of an stern wing rigged boat, must be built up to support the riggers. In the case of the bow wing, all the build up is at the bow, so any waves braking over the canvas, or rolling up the side of the boat have a better chance of being deflected. I contrast this with the personal experience of a wet backside every time I catch a significant cross-head wind in a stern wing rigged club 1x. Such boats could have the built up saxboards/wave breaker (not certain what the 'front of the cockpit is called??), but this would add weight/serve a single purpose.
Other advantages come down to comparisons between of Wing vs Conventional & Bow vs Stern arrangements.
1st Wing vs Conventional. It may appear that the conventional riggers are more efficient. They are lighter, appear simpler, all forces appear compressive/tensile, right? Wrong. The simple fact is that while this may be almost true of the riggers, it is certainly not true of the ribs in the boat which have to carry loads from one side to the other. These must carry significant bending loads, which offset the simplicity of the riggers. They are heavy & their weight is forced to be evenly distributed along the length of the boat. If bow loading coxed boats are anything to go by, it seams fairly safe to say that having this extra 'rigging' weight in the bow is advantageous, even if (due to FISA rules) the bow wing arrangement can't bring the overall weight down. That being said, if they have the potential to be lighter, the 'spare weight' can be put to better use: general durability, ballast at the bow of the boat (reduces pitching) ballast at the kelson (reduces rolling), aerodynamic fairing, or any number of other uses.
This may all be a bit '6 of one, 1/2 dozen of the other,' but what is certain is that the greatest stress (bending) in a conventional boat is in the ribs. With every stroke, they & the adjacent material flex & gradually becomes less stiff, eventually rendering the boat useless. Conversely, the only axial loads are carried by the hull of a bow wing boat. Distributing the mass of the ribs more evenly can make the hull generally more durable, while the large bending loads are confined to the rigger. Thus, the hull will last, while the (relatively) cheap rigger is left to weaken & be replaced when necessary.
Similarly, by having all the material concentrated in one place, a wing rigger is likely to be/can be made more resistant to impact, certainly compared to top stays. And while (as Carl rightly said) the sweep has no effect on drag, it does mean that if you run into something, it is more likely to get deflected away without damage (compared to conventional/top stay riggers) or snaring something (compared to plain (no top stay) stern wing riggers - if as happens occasionally I manage to run into one of a number of large sailors' buoys strewn around my stretch of water, the stern wing rigger drags them to the side of the boat, along with a fair bit of water into it, & pin it there, making backing out awkward (the buoy ends up in the way of the oar) & painstaking (must go a long way to 'unsnag' myself)).
Also, while sweep has no effect on drag, cross section does. Structurally, the wings of an aircraft would benefit from being wire braced, but no recent aircraft of note have them, because many small elements produce more drag than one big one. Thus, one 'rather thick' rigger is likely to produce less drag than 2, 3 or 4 smaller arms of a conventional rigger. More over, for what ever reason conventional riggers aren't built in aerodynamic sections, while wing riggers are & the notion that they're not aerodynamic is absurd. 'Tear drop' cross sections produce an order of magnitude less drag than circular ones - that is why the aerials, struts, etc. on aircraft are not circular - the E-3 is a classic, substantial example: http://air-boyne.com/boeing-e-3a-awacs-early-warning/ (compare side & head on views of the struts supporting the radome). Lastly, a symmetrical 'aerodynamic shape' aligned to the direction of airflow won't produce any aerodynamic (lifting) force, whereas in certain conditions, a cylinder can: http://www.mecaenterprises.com/vortex_shedding.htm On the other hand, if an aerodynamic section is made to rise & fall (due to rolling), the lift it would generate would actually (albeit very slightly in this case) oppose the rolling!
Bow vs Stern arrangements: By virtue of needing to facilitate rowing through the pin, a stern arrangement (stern wing or 2 stay - '3 stay without the top stay!) can only support the pin from below. While it is quite possible for this arrangement to be very stiff, a bending &/or torsional load is developed: that is unavoidable. Therefore, there will always be *some* pin pitching. The riggers can be stiffened, but this requires the rigger tubes to be thicker &/or wider, & the tendency will never go away. Similarly, a top stay can be added, but this requires yet more weight, and extra rib & the simple fact is that the axis of the top stay doesn't directly oppose the motion of the top of the pin, so some load will always be carried in a non ideal direction. Conversely, in a bow arrangement (bow wing or '2 stay back rigger') it is possible to support the pin symmetrically from above & below. With the 2 stay, since loads must still be carried predominantly in tension/compression, either they must come to a point at the pin (like the swift racing 2 stay back riggers) in which case there is again a risk of the oar striking the rigger, or not (like the Dreher side mounted riggers) in which case some torsion/bending loads will still be developed & in spite of the use of C brackets to support the pins, there will still be some pin pitching/rolling. The only way to avoid this is the bow wing rigger.
The last, maybe tenuous point is that bow wing riggers are easily the most conducive to mounting the pin further back. Any other arrangement either requires extra material or movement of the ribs which can have other effects, were as a bow wing rigger need only be shortened, making it even lighter.
The bottom line is there are many advantages, either intrinsic or potential. They are becoming far more common & as that happens, more of the advantages will be brought to the fore & further refined, so I very much doubt that they will simply go out of fashion. And if they do, it would be a big mistake - comparisons with petrol engines, gas turbines & hybrid cars (on an admittedly different level) spring to mind.
Mike
Jim Dwyer
Apr 26, 2012, 1:19:02 PM4/26/12
to
These are my personal views with no double blind scientific testing done to
back them up:
Disadvantages of a bow mounted rigger:
The rigger is larger and heavier and extra structure needs to be built into
the boat to support it.
If you car top your boat with the rigger off it may not fit into your car!
It gets in the way when you are putting the boat in the water/on stretchers
and taking it out. Specifically when you are rolling the boat to your waist
or over your head.
If you fall in the water it will be very difficult or maybe even impossible
to get back into the boat.
Advantages:
I have been told that the boat and oars feel more stable when doing starts
as compared to a stern rigger without backstays.
I believe this is because the pin on a bow mounted rigger is subjected to
less torque.
Personally I cannot tell the difference because I am a weak lightweight
masters rower. I imagine that a very strong elite rower may be able to feel
a difference in the first one or two strokes off of the start when applying
FULL pressure from a standing start.
Jim
wrote in message
news:2407791.309.1335451563875.JavaMail.geo-discussion-forums@vbbh3...
back them up:
Disadvantages of a bow mounted rigger:
The rigger is larger and heavier and extra structure needs to be built into
the boat to support it.
If you car top your boat with the rigger off it may not fit into your car!
It gets in the way when you are putting the boat in the water/on stretchers
and taking it out. Specifically when you are rolling the boat to your waist
or over your head.
If you fall in the water it will be very difficult or maybe even impossible
to get back into the boat.
Advantages:
I have been told that the boat and oars feel more stable when doing starts
as compared to a stern rigger without backstays.
I believe this is because the pin on a bow mounted rigger is subjected to
less torque.
Personally I cannot tell the difference because I am a weak lightweight
masters rower. I imagine that a very strong elite rower may be able to feel
a difference in the first one or two strokes off of the start when applying
FULL pressure from a standing start.
Jim
wrote in message
news:2407791.309.1335451563875.JavaMail.geo-discussion-forums@vbbh3...
Paul Flory
Apr 26, 2012, 1:52:39 PM4/26/12
to
I've owned a LW Fluidesign 2x since 2005 and have rowed in it with
many people and loaned it to many many others (>50?). General
reactions:
(1) good scullers adapt to the lack of visible riggers very very
quickly and often come to prefer the lack of structure (I was going to
say "clutter" but some here might object to that terminology!)
(2) visually the boat appears narrow, much more like a stretched
single than a more traditional boat, say a Filippi thanks to a smaller
splashbox ("saxboards"), yet it is not a particularly "wet" boat in
rough water
As with any setup there are plusses and minuses (my other boat has a
stern wing rigger and I have had conventional rigger boats, so I'm not
in any one camp).
Pluses of the Fluidesign wing design:
- pin is held at both ends via a "C" cup arrangement
- ends of rigger are vertical tubes, to which the C cup is attached
via a single bolt, making spread and height adjustments simple over a
wide range without affecting pitch in either axis
- height clips on the pin inside the C cup allow finer adjustments of
height
Minuses:
- the surfaces are so hard that I haven't been able to scratch marks
into them so that I can go back to previous settings without
remeasuring
- I don't know of any way to adjust pin pitch (standard inserts are
used for stern pitch, but inboard pitch is fixed AFAIK)
- one must be careful when mounting the riggers not to overtorque the
attachment screws as doing so can bend the mounting brackets (which
are replaceable) - snug plus 1/4 turn is the spec
There are other pluses and minuses to the boat. It certainly isn't
slow. Mine has done quite well in races - with or without me in it!!
And mine is EXACTLY at minimum weight (it has been used at trials), so
no fussing with ballast. And the price is very reasonable.
If money were not an issue, I'd buy a Van Dusen 2x ($15,000!!!) mainly
because its cockpit volume is very low, so shipping water in rough
conditions or rain is less of a concern. It is a rear wing design.
As for "feel" I can't say I notice any difference between the three
rigger types.
many people and loaned it to many many others (>50?). General
reactions:
(1) good scullers adapt to the lack of visible riggers very very
quickly and often come to prefer the lack of structure (I was going to
say "clutter" but some here might object to that terminology!)
(2) visually the boat appears narrow, much more like a stretched
single than a more traditional boat, say a Filippi thanks to a smaller
splashbox ("saxboards"), yet it is not a particularly "wet" boat in
rough water
As with any setup there are plusses and minuses (my other boat has a
stern wing rigger and I have had conventional rigger boats, so I'm not
in any one camp).
Pluses of the Fluidesign wing design:
- pin is held at both ends via a "C" cup arrangement
- ends of rigger are vertical tubes, to which the C cup is attached
via a single bolt, making spread and height adjustments simple over a
wide range without affecting pitch in either axis
- height clips on the pin inside the C cup allow finer adjustments of
height
Minuses:
- the surfaces are so hard that I haven't been able to scratch marks
into them so that I can go back to previous settings without
remeasuring
- I don't know of any way to adjust pin pitch (standard inserts are
used for stern pitch, but inboard pitch is fixed AFAIK)
- one must be careful when mounting the riggers not to overtorque the
attachment screws as doing so can bend the mounting brackets (which
are replaceable) - snug plus 1/4 turn is the spec
There are other pluses and minuses to the boat. It certainly isn't
slow. Mine has done quite well in races - with or without me in it!!
And mine is EXACTLY at minimum weight (it has been used at trials), so
no fussing with ballast. And the price is very reasonable.
If money were not an issue, I'd buy a Van Dusen 2x ($15,000!!!) mainly
because its cockpit volume is very low, so shipping water in rough
conditions or rain is less of a concern. It is a rear wing design.
As for "feel" I can't say I notice any difference between the three
rigger types.
Paul Flory
Apr 26, 2012, 2:09:33 PM4/26/12
to
On Apr 26, 1:19 pm, "Jim Dwyer" <jim.dw...@sympatico.ca> wrote:
> These are my personal views with no double blind scientific testing done to
> back them up:
>
> Disadvantages of a bow mounted rigger:
> The rigger is larger and heavier and extra structure needs to be built into
> the boat to support it.
> If you car top your boat with the rigger off it may not fit into your car!
> It gets in the way when you are putting the boat in the water/on stretchers
> and taking it out. Specifically when you are rolling the boat to your waist
> or over your head.
> If you fall in the water it will be very difficult or maybe even impossible
> to get back into the boat.
>
> Advantages:
>
> I have been told that the boat and oars feel more stable when doing starts
> as compared to a stern rigger without backstays.
> I believe this is because the pin on a bow mounted rigger is subjected to
> less torque.
> Personally I cannot tell the difference because I am a weak lightweight
> masters rower. I imagine that a very strong elite rower may be able to feel
> a difference in the first one or two strokes off of the start when applying
> FULL pressure from a standing start.
>
> Jim
Don't know about extra structure. My 2x is at weight, as I said.
> These are my personal views with no double blind scientific testing done to
> back them up:
>
> Disadvantages of a bow mounted rigger:
> The rigger is larger and heavier and extra structure needs to be built into
> the boat to support it.
> If you car top your boat with the rigger off it may not fit into your car!
> It gets in the way when you are putting the boat in the water/on stretchers
> and taking it out. Specifically when you are rolling the boat to your waist
> or over your head.
> If you fall in the water it will be very difficult or maybe even impossible
> to get back into the boat.
>
> Advantages:
>
> I have been told that the boat and oars feel more stable when doing starts
> as compared to a stern rigger without backstays.
> I believe this is because the pin on a bow mounted rigger is subjected to
> less torque.
> Personally I cannot tell the difference because I am a weak lightweight
> masters rower. I imagine that a very strong elite rower may be able to feel
> a difference in the first one or two strokes off of the start when applying
> FULL pressure from a standing start.
>
> Jim
Yes the rigger is large, but not THAT much larger than the stern wing
rigger from my other boat. The Fluid wing fits into a Subaru Outback
Wagon and surprisingly tidily into the current generation of Prius,
but it would be a good idea to check before buying.
I find putting my rear-wing 1x into the water a bit more awkward than
conventional rigger boats.
My Fluid is a 2x, so I haven't gone swimming from it (yet).
No idea about starts: I only use mine for head racing, but no
complaints from people who have borrowed it for sprints, mainly
masters, juniors, and U23 LW's.
Carl
Apr 26, 2012, 6:48:55 PM4/26/12
to
On 26/04/2012 15:46, rb...@cam.ac.uk wrote:
> This thread is rather old, so I am a little late to the discussion&/or no one might be reading any more, but as a (rowing) (aerospace) engineer, I feel I have to speak up against some of the backward& disappointing attitudes expressed in this thread.
>
> Firstly& fairly trivially - Carl, I think you may have got yourself a little tangled up re transonic speeds, etc. The speed of sound through water is very rarely (if ever) relevant when considering motion though water, so 'transonic speed' almost always pertains to speed through air (& more or less can't be achieved in water without super-cavitating, at which point the speed of sound through water is moot, etc., etc. basically it doesn't matter). The point being I think, that the speed of sound in air is circa 535mph, so John was only managing ~5 mph, I.e. normal speeds in a rowing boat!
>
> More importantly: bow wing riggers. I concede that I haven't done any analysis - my consideration is purely qualitative. It may be in some cases that it turns out that the numbers stack up against my argument, though I doubt it& in some cases this is impossible. Similarly, it is impossible to say conclusively that it will make any& all boats go faster - there are simply too many variables& it is more or less impossible to prove incontrovertibly - the same rower can't test the same boat at the same time (tiredness comes into play if tested consecutively) on exactly the same bit of water, but with different riggers, while any other comparative statements are unlikely to be conclusive. And rowers' preference would play a part. I also can't say that bow wing riggers are being introduced for purely, genuinely performance related reasons. However, this doesn't mean that it can't be ascertained with some certainty that they have advantages.
>
> The argument here& elsewhere, that had it been a good idea, it would have been done a long time before, is both flawed& misguided. The simple fact is that an idea has to be thought of at some point& in some cases it is not possible or maybe not economical for it to happen until something else does, namely developments in materials& manufacturing techniques - there's a reason that reciprocating steam engines were used in the past, but we don't load coal& water into our cars on a weekly/daily basis.
>
> One thing that can be said without ambiguity is that a bow wing arrangement interferes the least with the rower. Arguments about 'feeling naked' are indeed all *purely* in a rower's head. If perception was key, we'd all be rowing with pontoons à la arms only adaptive! (that's not a pop at adaptive rowers, btw, but the simple fact is able bodied rower don't need floats). Once you get used to the feeling, the fact that there are no ribs to catch your hips on, slides which can be made further apart to clear your calves, no riggers or cross stays in& around the feet& no, even vague, possibility of the oar handle/hands catching the rigger (eg. in rough weather), can all be seen as clear advantages.
>
> Another advantage to having all the mountings for the rigger at the 'bow end' of the cockpit is that, as with the entire saxboard of the a conventionally rigged boat& the stern of an stern wing rigged boat, must be built up to support the riggers. In the case of the bow wing, all the build up is at the bow, so any waves braking over the canvas, or rolling up the side of the boat have a better chance of being deflected. I contrast this with the personal experience of a wet backside every time I catch a significant cross-head wind in a stern wing rigged club 1x. Such boats could have the built up saxboards/wave breaker (not certain what the 'front of the cockpit is called??), but this would add weight/serve a single purpose.
>
> Other advantages come down to comparisons between of Wing vs Conventional& Bow vs Stern arrangements.
>
> 1st Wing vs Conventional. It may appear that the conventional riggers are more efficient. They are lighter, appear simpler, all forces appear compressive/tensile, right? Wrong. The simple fact is that while this may be almost true of the riggers, it is certainly not true of the ribs in the boat which have to carry loads from one side to the other. These must carry significant bending loads, which offset the simplicity of the riggers. They are heavy& their weight is forced to be evenly distributed along the length of the boat. If bow loading coxed boats are anything to go by, it seams fairly safe to say that having this extra 'rigging' weight in the bow is advantageous, even if (due to FISA rules) the bow wing arrangement can't bring the overall weight down. That being said, if they have the potential to be lighter, the 'spare weight' can be put to better use: general durability, ballast at the bow of the boat (reduces pitching) ballast at the kelson (reduces rolling), aerodynamic
fairing, or any number of other uses.
>
> This may all be a bit '6 of one, 1/2 dozen of the other,' but what is certain is that the greatest stress (bending) in a conventional boat is in the ribs. With every stroke, they& the adjacent material flex& gradually becomes less stiff, eventually rendering the boat useless. Conversely, the only axial loads are carried by the hull of a bow wing boat. Distributing the mass of the ribs more evenly can make the hull generally more durable, while the large bending loads are confined to the rigger. Thus, the hull will last, while the (relatively) cheap rigger is left to weaken& be replaced when necessary.
>
> Similarly, by having all the material concentrated in one place, a wing rigger is likely to be/can be made more resistant to impact, certainly compared to top stays. And while (as Carl rightly said) the sweep has no effect on drag, it does mean that if you run into something, it is more likely to get deflected away without damage (compared to conventional/top stay riggers) or snaring something (compared to plain (no top stay) stern wing riggers - if as happens occasionally I manage to run into one of a number of large sailors' buoys strewn around my stretch of water, the stern wing rigger drags them to the side of the boat, along with a fair bit of water into it,& pin it there, making backing out awkward (the buoy ends up in the way of the oar)& painstaking (must go a long way to 'unsnag' myself)).
>
> Also, while sweep has no effect on drag, cross section does. Structurally, the wings of an aircraft would benefit from being wire braced, but no recent aircraft of note have them, because many small elements produce more drag than one big one. Thus, one 'rather thick' rigger is likely to produce less drag than 2, 3 or 4 smaller arms of a conventional rigger. More over, for what ever reason conventional riggers aren't built in aerodynamic sections, while wing riggers are& the notion that they're not aerodynamic is absurd. 'Tear drop' cross sections produce an order of magnitude less drag than circular ones - that is why the aerials, struts, etc. on aircraft are not circular - the E-3 is a classic, substantial example: http://air-boyne.com/boeing-e-3a-awacs-early-warning/ (compare side& head on views of the struts supporting the radome). Lastly, a symmetrical 'aerodynamic shape' aligned to the direction of airflow won't produce any aerodynamic (lifting) force, whereas in certain c
an aerodynamic section is made to rise& fall (due to rolling), the lift
hey must come to a point at the pin (like the swift racing 2 stay back
riggers) in which case there is again a risk of the oar striking the
rigger, or not (like the Dreher side mounted riggers) in which case some
torsion/bending loads will still be developed& in spite of the use of C
>
> Mike
Is a 2 year lapse between posts in a thread a record for RSR?
You might, just ever so slightly, be taking the piss over my remarks on
transonic velocity. I certainly was - since a little mild silliness is
fun & hurts no one. But was I "tangled up" over transonic flows?
Certainly not. IIRC, in that particular exchange we moved from air to
water in one swiftly casual bound. No matter: if we're to talk about
ultra-fast bodies in water, certain Russian torpedoes do, I understand,
get a big drag reduction due to a vapour pocket forming at the nose -
but please don't take my word for it.
Your 5mph figure really is _not_ a normal boat speed, except for a
rowing pontoon or a park lake skiff. 3.5 to 5 metres/sec (8 to 11mph)
is the range for moderate to elite scullers.
Before pronouncing on the aerodynamics of riggers, it's a good idea to
have real data, which you admit to lacking. I _have_ done that work -
we built our own wind tunnel, equipped with anemometer to measure air
flow velocities & a force gauge system. We have measured & compared the
drag on a range of different rigger makes, each set up on a realistic
section of boat. So I can fairly claim to have some authority in these
matters.
Be wary, too, of handy analogies. We don't load coal & water into cars
because liquid-fuelled IC engines for road & air transport had the
lion's share of investment over the last 120 years due to the immediate
convenience, high energy density & relative cleanliness of fuelling with
petroleum distillates. But Diesel's original design was for a
compression ignition engine to run on coal dust. Solid-fired
reciprocating, & then turbine, steam engines have been the principal
means of marine propulsion until quite recently, & of electric power
generation even now, this technology being more efficient & economical
at scales rather larger than cars. Steam boilers are also hard to scale
downwards as heat transfer capacity is proportional to the square of
vehicle principal length dimension while vehicle & engine mass are
proportional to that dimension cubed - ask those who make miniature
steam plant.
Obviously perception matters in acceptance of changes of rigging or
boat, since a rower may go faster in a boat he/she believes in, all
thing being otherwise equal. But perception is malleable through
promotion & familiarity, even where there are no real benefits. We are
not wholly rational beings.
It would be irrational to argue that what has not yet been tried must be
no good, but a lot of rowers love to do just that. Equally, another lot
of rowers fall for every new gimmick. Humans are perverse like that :)
It is no less irrational to make blunt statements about what
interferes most with which. Nor do your perceptions of the supposed
disadvantages of other layouts count as any more than opinion. Only
when scullers go consistently faster when using rig type A than with rig
type B can you go from prejudice to proof. That's not yet!
Next, to your structural case. I think fail to grasp the need to
distribute forces properly within a thin-shell monocoque. Focussing the
loads in one place would not be a good idea. Anyway, the lightest,
stiffest structure is that which has the shortest load paths. In a
conventional rigger the path from 1 pin to the other as short as it can
be, & the rigger shoulder (which is very light) forms a direct & rigid
part of that path despite carrying the highest bending moment in the
system, while distributing loads into saxboards & other parts of the
shell is structurally sound in optimising the overall structure for its
many load cases. Ideally every part of a system performs multiple
functions & there is no benefit from having one item per duty. If the
washboards don't do their job, that's bad design - period - but you
can't extrapolate from the particular to the general.
As for your weight distribution arguments - I'm afraid these have no
validity.
Some conventional riggers are built with aerofoil section, & not
sensible conventional rigger needs more than 2 stays. For equal overal
rigger stiffness, bow & stern-mounted single-stay riggers have generally
thicker sections for the same vertical stiffness (end movement under
bending being proportional to cube of stay length), so windage is
significantly increased both by increase in projected frontal area & by
much increased overall surface area, while the fact is you don't get the
drag reductions you like to predict for the current aerofoil sections -
remember anyway that we are talking not about a stay but an entire rigger.
Sorry - aerofoil shapes _do_ produce significant lift forces (it's what
they do!) - since the air flow near the water surface is usually rather
turbulent & thus prone to generate exactly the kind of oscillatory lift
forces (buffeting) which you want to deny. Sure, a cylinder can
generate buffeting effects too, due as you say to von Karman vortex
shedding. This tends to happen at certain values of Reynolds number &,
with round rigger stays on conventional riggers, has never been a
detectable problem. Indeed, you don't get oars wobbled out of your
hands by the same effects on their round shafts either - & in part
that's because resonance of that kind would require the same phase &
frequency of vortex shedding to exist along the full length of the
shaft, which doesn't seem to happen.
In your rather rambling foray in your comparison of what you see as the
demerits of non-bow-mounted riggers you make so many wild presumptions
it's like watching the flight of a butterfly. So I'd best not get
started. I suggest you stop proposing &, instead, sit down to do some
proper stress analysis. People are too keen to rush to presumption &
quasi-authoritative pronouncements, this being so much easier than doing
the essential maths which would firmly dispel most of their fondly-held
beliefs. We make 2-stay scull riggers which need no topstay, backstay
or cinquieme barre, so what are we doing wrong?
Your point on pin mounting position & on being able to move it towards
the bow is, as you say, entirely tenuous. Why is this any better than
moving the stretcher astern (assume the designer knows where he wants
the centre of mass better than the sculler does)? And how is it done
more easily with a bow mounted rigger. Methinks you are clutching at
debating straws?
Finally, there is a fundamental problem with petrol engines, gas
turbines & hybrid cars - they consume excessive amounts of energy &
cause the release of unnecessarily large quantities of CO2 & other
deleterious substances. But that's another argument for another time &
place.
You may think I've been unduly tough on you, but you are a student at
one of the UK's most prestigious academic & rowing universities &, as an
engineering graduate myself, I do look for high standards of academic
rigour in products of such fine establishments. I'm sure your
supervisors take a similar approach, & that you would not expect less
from RSR - which (BTW) you can access perfectly well without needing to
pass through the maw of the ghastly Google Groups, if you are so minded.
I'll await your responses with interest, but don't let it take another 2
years, please
:)
> This thread is rather old, so I am a little late to the discussion&/or no one might be reading any more, but as a (rowing) (aerospace) engineer, I feel I have to speak up against some of the backward& disappointing attitudes expressed in this thread.
>
> Firstly& fairly trivially - Carl, I think you may have got yourself a little tangled up re transonic speeds, etc. The speed of sound through water is very rarely (if ever) relevant when considering motion though water, so 'transonic speed' almost always pertains to speed through air (& more or less can't be achieved in water without super-cavitating, at which point the speed of sound through water is moot, etc., etc. basically it doesn't matter). The point being I think, that the speed of sound in air is circa 535mph, so John was only managing ~5 mph, I.e. normal speeds in a rowing boat!
>
> More importantly: bow wing riggers. I concede that I haven't done any analysis - my consideration is purely qualitative. It may be in some cases that it turns out that the numbers stack up against my argument, though I doubt it& in some cases this is impossible. Similarly, it is impossible to say conclusively that it will make any& all boats go faster - there are simply too many variables& it is more or less impossible to prove incontrovertibly - the same rower can't test the same boat at the same time (tiredness comes into play if tested consecutively) on exactly the same bit of water, but with different riggers, while any other comparative statements are unlikely to be conclusive. And rowers' preference would play a part. I also can't say that bow wing riggers are being introduced for purely, genuinely performance related reasons. However, this doesn't mean that it can't be ascertained with some certainty that they have advantages.
>
> The argument here& elsewhere, that had it been a good idea, it would have been done a long time before, is both flawed& misguided. The simple fact is that an idea has to be thought of at some point& in some cases it is not possible or maybe not economical for it to happen until something else does, namely developments in materials& manufacturing techniques - there's a reason that reciprocating steam engines were used in the past, but we don't load coal& water into our cars on a weekly/daily basis.
>
> One thing that can be said without ambiguity is that a bow wing arrangement interferes the least with the rower. Arguments about 'feeling naked' are indeed all *purely* in a rower's head. If perception was key, we'd all be rowing with pontoons à la arms only adaptive! (that's not a pop at adaptive rowers, btw, but the simple fact is able bodied rower don't need floats). Once you get used to the feeling, the fact that there are no ribs to catch your hips on, slides which can be made further apart to clear your calves, no riggers or cross stays in& around the feet& no, even vague, possibility of the oar handle/hands catching the rigger (eg. in rough weather), can all be seen as clear advantages.
>
> Another advantage to having all the mountings for the rigger at the 'bow end' of the cockpit is that, as with the entire saxboard of the a conventionally rigged boat& the stern of an stern wing rigged boat, must be built up to support the riggers. In the case of the bow wing, all the build up is at the bow, so any waves braking over the canvas, or rolling up the side of the boat have a better chance of being deflected. I contrast this with the personal experience of a wet backside every time I catch a significant cross-head wind in a stern wing rigged club 1x. Such boats could have the built up saxboards/wave breaker (not certain what the 'front of the cockpit is called??), but this would add weight/serve a single purpose.
>
> Other advantages come down to comparisons between of Wing vs Conventional& Bow vs Stern arrangements.
>
> 1st Wing vs Conventional. It may appear that the conventional riggers are more efficient. They are lighter, appear simpler, all forces appear compressive/tensile, right? Wrong. The simple fact is that while this may be almost true of the riggers, it is certainly not true of the ribs in the boat which have to carry loads from one side to the other. These must carry significant bending loads, which offset the simplicity of the riggers. They are heavy& their weight is forced to be evenly distributed along the length of the boat. If bow loading coxed boats are anything to go by, it seams fairly safe to say that having this extra 'rigging' weight in the bow is advantageous, even if (due to FISA rules) the bow wing arrangement can't bring the overall weight down. That being said, if they have the potential to be lighter, the 'spare weight' can be put to better use: general durability, ballast at the bow of the boat (reduces pitching) ballast at the kelson (reduces rolling), aerodynamic
fairing, or any number of other uses.
>
>
> Similarly, by having all the material concentrated in one place, a wing rigger is likely to be/can be made more resistant to impact, certainly compared to top stays. And while (as Carl rightly said) the sweep has no effect on drag, it does mean that if you run into something, it is more likely to get deflected away without damage (compared to conventional/top stay riggers) or snaring something (compared to plain (no top stay) stern wing riggers - if as happens occasionally I manage to run into one of a number of large sailors' buoys strewn around my stretch of water, the stern wing rigger drags them to the side of the boat, along with a fair bit of water into it,& pin it there, making backing out awkward (the buoy ends up in the way of the oar)& painstaking (must go a long way to 'unsnag' myself)).
>
> Also, while sweep has no effect on drag, cross section does. Structurally, the wings of an aircraft would benefit from being wire braced, but no recent aircraft of note have them, because many small elements produce more drag than one big one. Thus, one 'rather thick' rigger is likely to produce less drag than 2, 3 or 4 smaller arms of a conventional rigger. More over, for what ever reason conventional riggers aren't built in aerodynamic sections, while wing riggers are& the notion that they're not aerodynamic is absurd. 'Tear drop' cross sections produce an order of magnitude less drag than circular ones - that is why the aerials, struts, etc. on aircraft are not circular - the E-3 is a classic, substantial example: http://air-boyne.com/boeing-e-3a-awacs-early-warning/ (compare side& head on views of the struts supporting the radome). Lastly, a symmetrical 'aerodynamic shape' aligned to the direction of airflow won't produce any aerodynamic (lifting) force, whereas in certain c
an aerodynamic section is made to rise& fall (due to rolling), the lift
it would generate would actually (albeit very slightly in this case)
oppose the rolling!
>
> Bow vs Stern arrangements: By virtue of needing to facilitate rowing through the pin, a stern arrangement (stern wing or 2 stay - '3 stay without the top stay!) can only support the pin from below. While it is quite possible for this arrangement to be very stiff, a bending&/or torsional load is developed: that is unavoidable. Therefore, there will always be *some* pin pitching. The riggers can be stiffened, but this requires the rigger tubes to be thicker&/or wider,& the tendency will never go away. Similarly, a top stay can be added, but this requires yet more weight, and extra rib& the simple fact is that the axis of the top stay doesn't directly oppose the motion of the top of the pin, so some load will always be carried in a non ideal direction. Conversely, in a bow arrangement (bow wing or '2 stay back rigger') it is possible to support the pin symmetrically from above& below. With the 2 stay, since loads must still be carried predominantly in tension/compression, either t
oppose the rolling!
>
hey must come to a point at the pin (like the swift racing 2 stay back
riggers) in which case there is again a risk of the oar striking the
rigger, or not (like the Dreher side mounted riggers) in which case some
brackets to support the pins, there will still be some pin
pitching/rolling. The only way to avoid this is the bow wing rigger.
>
> The last, maybe tenuous point is that bow wing riggers are easily the most conducive to mounting the pin further back. Any other arrangement either requires extra material or movement of the ribs which can have other effects, were as a bow wing rigger need only be shortened, making it even lighter.
>
> The bottom line is there are many advantages, either intrinsic or potential. They are becoming far more common& as that happens, more of the advantages will be brought to the fore& further refined, so I very much doubt that they will simply go out of fashion. And if they do, it would be a big mistake - comparisons with petrol engines, gas turbines& hybrid cars (on an admittedly different level) spring to mind.
pitching/rolling. The only way to avoid this is the bow wing rigger.
>
> The last, maybe tenuous point is that bow wing riggers are easily the most conducive to mounting the pin further back. Any other arrangement either requires extra material or movement of the ribs which can have other effects, were as a bow wing rigger need only be shortened, making it even lighter.
>
>
> Mike
Is a 2 year lapse between posts in a thread a record for RSR?
You might, just ever so slightly, be taking the piss over my remarks on
transonic velocity. I certainly was - since a little mild silliness is
fun & hurts no one. But was I "tangled up" over transonic flows?
Certainly not. IIRC, in that particular exchange we moved from air to
water in one swiftly casual bound. No matter: if we're to talk about
ultra-fast bodies in water, certain Russian torpedoes do, I understand,
get a big drag reduction due to a vapour pocket forming at the nose -
but please don't take my word for it.
Your 5mph figure really is _not_ a normal boat speed, except for a
rowing pontoon or a park lake skiff. 3.5 to 5 metres/sec (8 to 11mph)
is the range for moderate to elite scullers.
Before pronouncing on the aerodynamics of riggers, it's a good idea to
have real data, which you admit to lacking. I _have_ done that work -
we built our own wind tunnel, equipped with anemometer to measure air
flow velocities & a force gauge system. We have measured & compared the
drag on a range of different rigger makes, each set up on a realistic
section of boat. So I can fairly claim to have some authority in these
matters.
Be wary, too, of handy analogies. We don't load coal & water into cars
because liquid-fuelled IC engines for road & air transport had the
lion's share of investment over the last 120 years due to the immediate
convenience, high energy density & relative cleanliness of fuelling with
petroleum distillates. But Diesel's original design was for a
compression ignition engine to run on coal dust. Solid-fired
reciprocating, & then turbine, steam engines have been the principal
means of marine propulsion until quite recently, & of electric power
generation even now, this technology being more efficient & economical
at scales rather larger than cars. Steam boilers are also hard to scale
downwards as heat transfer capacity is proportional to the square of
vehicle principal length dimension while vehicle & engine mass are
proportional to that dimension cubed - ask those who make miniature
steam plant.
Obviously perception matters in acceptance of changes of rigging or
boat, since a rower may go faster in a boat he/she believes in, all
thing being otherwise equal. But perception is malleable through
promotion & familiarity, even where there are no real benefits. We are
not wholly rational beings.
It would be irrational to argue that what has not yet been tried must be
no good, but a lot of rowers love to do just that. Equally, another lot
of rowers fall for every new gimmick. Humans are perverse like that :)
It is no less irrational to make blunt statements about what
interferes most with which. Nor do your perceptions of the supposed
disadvantages of other layouts count as any more than opinion. Only
when scullers go consistently faster when using rig type A than with rig
type B can you go from prejudice to proof. That's not yet!
Next, to your structural case. I think fail to grasp the need to
distribute forces properly within a thin-shell monocoque. Focussing the
loads in one place would not be a good idea. Anyway, the lightest,
stiffest structure is that which has the shortest load paths. In a
conventional rigger the path from 1 pin to the other as short as it can
be, & the rigger shoulder (which is very light) forms a direct & rigid
part of that path despite carrying the highest bending moment in the
system, while distributing loads into saxboards & other parts of the
shell is structurally sound in optimising the overall structure for its
many load cases. Ideally every part of a system performs multiple
functions & there is no benefit from having one item per duty. If the
washboards don't do their job, that's bad design - period - but you
can't extrapolate from the particular to the general.
As for your weight distribution arguments - I'm afraid these have no
validity.
Some conventional riggers are built with aerofoil section, & not
sensible conventional rigger needs more than 2 stays. For equal overal
rigger stiffness, bow & stern-mounted single-stay riggers have generally
thicker sections for the same vertical stiffness (end movement under
bending being proportional to cube of stay length), so windage is
significantly increased both by increase in projected frontal area & by
much increased overall surface area, while the fact is you don't get the
drag reductions you like to predict for the current aerofoil sections -
remember anyway that we are talking not about a stay but an entire rigger.
Sorry - aerofoil shapes _do_ produce significant lift forces (it's what
they do!) - since the air flow near the water surface is usually rather
turbulent & thus prone to generate exactly the kind of oscillatory lift
forces (buffeting) which you want to deny. Sure, a cylinder can
generate buffeting effects too, due as you say to von Karman vortex
shedding. This tends to happen at certain values of Reynolds number &,
with round rigger stays on conventional riggers, has never been a
detectable problem. Indeed, you don't get oars wobbled out of your
hands by the same effects on their round shafts either - & in part
that's because resonance of that kind would require the same phase &
frequency of vortex shedding to exist along the full length of the
shaft, which doesn't seem to happen.
In your rather rambling foray in your comparison of what you see as the
demerits of non-bow-mounted riggers you make so many wild presumptions
it's like watching the flight of a butterfly. So I'd best not get
started. I suggest you stop proposing &, instead, sit down to do some
proper stress analysis. People are too keen to rush to presumption &
quasi-authoritative pronouncements, this being so much easier than doing
the essential maths which would firmly dispel most of their fondly-held
beliefs. We make 2-stay scull riggers which need no topstay, backstay
or cinquieme barre, so what are we doing wrong?
Your point on pin mounting position & on being able to move it towards
the bow is, as you say, entirely tenuous. Why is this any better than
moving the stretcher astern (assume the designer knows where he wants
the centre of mass better than the sculler does)? And how is it done
more easily with a bow mounted rigger. Methinks you are clutching at
debating straws?
Finally, there is a fundamental problem with petrol engines, gas
turbines & hybrid cars - they consume excessive amounts of energy &
cause the release of unnecessarily large quantities of CO2 & other
deleterious substances. But that's another argument for another time &
place.
You may think I've been unduly tough on you, but you are a student at
one of the UK's most prestigious academic & rowing universities &, as an
engineering graduate myself, I do look for high standards of academic
rigour in products of such fine establishments. I'm sure your
supervisors take a similar approach, & that you would not expect less
from RSR - which (BTW) you can access perfectly well without needing to
pass through the maw of the ghastly Google Groups, if you are so minded.
I'll await your responses with interest, but don't let it take another 2
years, please
:)
Mike
Apr 27, 2012, 12:08:58 AM4/27/12
to
Again, some rather odd perspectives here;
-As I said, the rigger might be larger than a stern wing & heavier than a conventional rigger, but the boat won't necessarily be heavier & the weight will be better distributed - towards the bow & with no ribs.
-It might be larger & bulkier in the boat than others, but it should certainly be possible (in the future, in principle) for it to be made collapsible/ foldable if there were a call for it to be made that way.
-If the pin is in the same place as an otherwise rigged boat, I see no reason for it to get in the way more - you just need to adapt to it's new position by 'approaching' the boat from the stern - it's certainly better than a 3 stay boat, or (in terms of getting trapped by the rigger) than a stern wing with top stay.
-I don't fall in all that much personally (? :D ) so I'm not to sure about getting back in, but again, why not approach it from the stern?
-If it isn't possible to adjust pitch angles about both longitudinal & lateral axes, then that is very disappointing & is a flaw in the design not the principle of the rigger. If the C-bracket were fixed to the rigger with a single bolt through a slot in the bracket, it would allow the bracket to be rolled & pitched over very wide angles. Regardless of the shape of the bracket, if a single bolt were used, roll could be adjusted. My opinion would be that the optimum shap for a 'C-bracket' would be 'V' (pure compression, no bending). Pitch could then be adjust simply by having one of the arms of the V fitted with a slot (as for span on most riggers) or an adjustment screw.
-As for scratching to mark the rigger - I can't help but feel that this is a bit distructive, permenent & unecessary; what's wrong with a marker pen??
Also, without getting too technical/theoretical, if something is a problem for someone bigger/stronger than you, but isn't for you then the rigger is over designed for you - FISA regulations aside, it could be made lighter & still function correctly; if that were to happen, you would then benefit from the change in the same way that a "very strong elite rower" would! :D
Mike
-As I said, the rigger might be larger than a stern wing & heavier than a conventional rigger, but the boat won't necessarily be heavier & the weight will be better distributed - towards the bow & with no ribs.
-It might be larger & bulkier in the boat than others, but it should certainly be possible (in the future, in principle) for it to be made collapsible/ foldable if there were a call for it to be made that way.
-If the pin is in the same place as an otherwise rigged boat, I see no reason for it to get in the way more - you just need to adapt to it's new position by 'approaching' the boat from the stern - it's certainly better than a 3 stay boat, or (in terms of getting trapped by the rigger) than a stern wing with top stay.
-I don't fall in all that much personally (? :D ) so I'm not to sure about getting back in, but again, why not approach it from the stern?
-If it isn't possible to adjust pitch angles about both longitudinal & lateral axes, then that is very disappointing & is a flaw in the design not the principle of the rigger. If the C-bracket were fixed to the rigger with a single bolt through a slot in the bracket, it would allow the bracket to be rolled & pitched over very wide angles. Regardless of the shape of the bracket, if a single bolt were used, roll could be adjusted. My opinion would be that the optimum shap for a 'C-bracket' would be 'V' (pure compression, no bending). Pitch could then be adjust simply by having one of the arms of the V fitted with a slot (as for span on most riggers) or an adjustment screw.
-As for scratching to mark the rigger - I can't help but feel that this is a bit distructive, permenent & unecessary; what's wrong with a marker pen??
Also, without getting too technical/theoretical, if something is a problem for someone bigger/stronger than you, but isn't for you then the rigger is over designed for you - FISA regulations aside, it could be made lighter & still function correctly; if that were to happen, you would then benefit from the change in the same way that a "very strong elite rower" would! :D
Mike
Mike
Apr 27, 2012, 4:20:16 AM4/27/12
to
1st, I'll say I'm not too clear on everything you're saying, so I'll avoid/query as necessary. I take it that RSR is a forum - I'm not familiar with it, as I came across this thread on Google groups & not anywhere else - you're right, it isn't particularly... 'compact!' Likewise, the delay is purely accidental - I had forgotten the name (Fluidesign) of the company who 'first' (at least recently) manufactured bow wing riggers - the Google search brought me here.
I wouldn't say I was 'taking the piss' about transonic velocity, but I was semi serious - by your own admission, you 'shouldn't have been attempting maths at bed time,' & it was tangential to the thrust of my post. My point was that the speed of sound through water is rarely worth considering in flow problems. You are quite right about the Russian torpedoes - they are in fact use the super- cavitation which as I mentioned; indeed, that phenomenon occurs (typically) well below the speed of sound in water & renders it moot by surround the body with... 'something other than water!' In either case, the speed of sound is moot. Similarly, the 5mph, is tangential, but it was only a ball park figure (eg. paddling a 1x, as opposed to racing). But it only comes down to what 'the lower end of the transonic region' happens to be; if on the day in question it was 540mph, then '530 below' puts you right in the 8-11mph bracket you mentioned.
Similarly, the analogies are a bit off topic, & you're right in much of what you say, & I am quite aware of most of it too, including power generation, etc. I'm not in any way disparaging of steam power - the Rankine cycle was a proposed subject of mine for a 4th year project & has much potential. My point was that often current technologies are over egged at the expense of underdeveloped alternative - in the case of steam power, steam engines (reciprocating, non-condensing, lacking in feed pumps to lift the pressure up to efficient levels) were allowed to dominate over the British rail way system beyond WWII, gas turbines were ignored until WWII forced people to listen to Frank Whittle & now the likes of Jeremy Clarkson rant about Hybrid cars without any genuine understanding of their operation or benefits. In each case, the preceding technology was well developed, so it was used well beyond a point at which a new alternative could have been superior.
That being said, I hope you're not suggesting that steam power was ever a sensible source of automotive power. Steam power derives it's efficiency, as you said from scale. It is also of significant value in it's ability to use heat at low temperature - nuclear, geothermal, solar-thermal & in particular, gas turbine exhaust (combined cycles). But to be practical it either needs to have a large source of very clean water, or unclean water & space for a condenser - this was never the case in any vehicle apart from ships, & even then space isn't limitless/worthless. It was used when it was, because materials which could tolerate the higher temperatures associated with IC engines, didn't develop until later (the materials/manufacturing methods point which I mentioned). Once these evolved, steam engines, in there Victorian form, were doomed. It is fortunate that the tendencies which prevailed in the rail industry didn't extend to cars, otherwise some of the investment you mentioned might well have been wasted in 'steam cars.'
The same can, unfortunately be said about IC engine. Your quite right - petrol, gas turbine or hybrid, the CURRENT problems are the same. However, gas turbine engines can be made, materials & control subtleties aside, to run on almost any fuel (including hydrogen/synthesised methane) while the hybrid car industry is a means by which electric propulsion systems for cars can be developed - once greener energy takes over (assuming this happens before London, Cardiff, Liverpool, etc. are under water & half of use don't care either way!) such developments are likely to be of much more value than those aimed at eking out every drop from IC engines.
On to the subject at hand. I did say that I hadn't done any analysis. The reason for that, is if I did, especially without being employed to do so, it would risk taking over my life. However, I pride myself on considering my opinions carefully & changing them in the face of suitable evidence. & you're right, what I have said is to an extent an opinion. But all we can say at this point is to an extent opinion. Only time can tell whether bow wing riggers will make boats go faster - I don't think there is a flaw in my reasoning regarding comparison, or that a balanced account can be made of the pro's & cons until this arrangement is developed - compared to other arrangements, you must admit it is in its infancy - I hope your not (& don't think that you are) trying to kill it before it does (develop).
Regarding structures, I think you're over simplifying the matter. The shortest path is not always best. Sometimes, finding the most efficient way to carry a load is more important than a short path - consider a suspension bridge: deck to suspending cables, to main cable, to pier/abutment. It is far from the shortest path, but it is more efficient, because (in this case) a disproportionate amount of load can be carried in pure tension. In the case of the shoulder, just because it is the shortest path, doesn't make it the best, particularly, since the optimum load path in this case (I.e. a straight line though the centroid of the oar loom) is blocked in certain phases of the stroke, leading to the pin pitching issues, torsion, etc. As for distributing loads; in some cases it makes perfect sense to use each part of a system for multiple uses, but there are often penalties to be paid. The main function of the hull is to carry a distributed load of buoyancy & to direct the water. By virtue of being beam-like, it is also suitable for carrying axial & bending loads in certain directions. However, it is not well suited to carrying transverse, 'crushing' loads, which is why the cockpit needs reinforcements simply to support the weight of the rower. Add in the load from the riggers & you soon end up loosing stiffness (over time) - you didn't comment on my point that the bow wing removed the stress from the hull, making it last better (?). As for the washboards, my point was more or less in line with what you're saying - by having the rigger mountings in the bow of the cockpit, they can serve both to do this & deflect water. Other arrangements require the task to be carried out by separate structures. As for focusing the loads, I'm not sure this is an issue - the whole point of the wing rigger is that much of the loads are contained in the rigger & never pas into 'one place' on the hull - only axial forces are transmitted to the hull, which are neither as large or concentrated as those which are developed by multi-stay riggers.
You talk about rigger stiffness - I'm not to sure of the context. To my mind, the critical point about rigger stiffness is the deflection under motive load. In the case of a bow wing, this consists of the bending of the rigger & stretching of the hull. In most analyses, axial extensions are simply ignored, since they are so small. Deflections of beams & triangulated structures are significant & are usually the main components in a structure. In **most** cases, torsional deflections aren't relevant, simply because they 'designed out' & would be overwhelming if they weren't - few structures make significant use of torsional rigidity directly, but conventional & stern wing riggers require all three of the latter. Again, I haven't worked in the field, but it seems probable that it is easier to make a bow wing rigger stiffer in the direction of propulsive force. Vertical stiffness is another issue, but I can't see why it is a big one. However: to the best of my recollection, bending stiffness is proportional to both the width & skin thickness of a (hollow) section, the square of its depth & inversely proportional to the length of the beam. Therefore, a small increase in the section of a wing rigger should easily offset the increase in length compared to the length of a stay. Similarly, as I said, one big wing rigger (even of circular cross section) is likely to produce less drag than many smaller stays of a multi-stay system combined. The big difference in vertical stiffness is that now the bow wing rigger suffers from torsional issues. However, a closed, quasi-elliptical hollow sections would have relatively good torsional properties; given that the section is designed to carry significant propulsive forces, I really can't see how torsional &/or bending stiffness will be a limiting factor when subjected to relatively small vertical loads (???)
The comparisons that I made were such as to express my perspective as clearly as possible, since they do ultimately come down to comparisons with other rigger types. I do concede that they, this & indeed your post are all rather longer than ideal, but that was the best I could do. I'm not sure where you feel I made presumptions, wild or otherwise & I would like to clarify them, but I really don't feel this is the best place. But simply, I would say that 2 stay rigger without top stays need reinforcement in torsion & bending that the addition of a top stay &/or replacement with a bow wing might well supplant :$ In essence, the rigger/rigging could be made lighter. This might not be the case, but without access to the necessary data, any calculations which I might make would similarly be based on assumptions, or at best on designs which as I said, are relatively underdeveloped.
Weight distribution - I'm not fully clear on this. I must say, I could rationalise a reason why having weight at the bow being beneficial, while this I don't think is true of the reverse. But unless I'm mistaken, bow loaded 4+ are acknowledged to be quicker than stern loaded. Any ballast needed to bring a boat up to FISA minimum weight tends to be placed towards the bow. If this is not the case, I stand corrected. If it is, why? & why is it not equally the case for rigging weight?
Pin position - just last week, a GB rowing technical director pointed out that many scullers row much too far behind the pin. In the case of stern wing riggers, this flawed arrangement can make the wing smaller. In the case of a conventional rigger, having the pin behind the shoulder makes the rigger far less efficient - as you said, it's advantage is in having the shortest possible load path, while moving the rib back means that the sculler is more likely to hit it with their hips. Moving the stretcher back would have either the same effect, or prevent the rower from getting their shins vertical at the catch (& surely affect the pitch of the boat - if not other things must be adjusted, in which case everything is moving *except* for the pin! :p). My point wasn't one of boat set up, but that, in general, from a design point of view, having the pin further back is better as it makes setting up the boat to row through the pin easier. More over, having the pin further back with a bow wing rigger makes it more compact, whereas other arrangements are made heavier.
Now, aerodynamics. I must admit, I hadn't didn't considered buffeting & you're quite right about that. Since I am concerned with performance in poor conditions, this is a valid consideration. If you've done extensive testing on riggers, I'd have to yield to your knowledge, at least without being able to look at the data myself. Also, while I am aware of vortex shedding & the fundamentals of how/why it happens, I am not intimately familiar with the phenomenon. However: I wouldn't have said it is ever likely to be an issue with the oar, since it is continuously accelerating. This is not so much the case with the rigger. Also, while aerofoil shapes *can* produce lift, my point was that it is not necessarily the case. Take my example of the E-3 - those aerofoils, or more precisely aerodynamic struts, are intended to generate absolutely no lift. I'm flip flopping slightly here, but in calm conditions, although the air near the water might be turbulent, paradoxically, this doesn't mean it moves up & down all that much! Turbulence is a misunderstood phenomenon & I doubt (in calm conditions) that a wing rigger would produce that much lift.* As for drag, again genuine figures take precedence. However, as a part of my degree, I did an experiment comparing (amongst other things) the drag on a sphere & 'aerodynamic' body of equal diameter. While this is not quite the same as comparing prismatic bodies (like riggers stay/similar) there are solid analogies to be made - the difference in coefficient of drag for Reynolds numbers typical of a rigger were found to be more than twice as high for the sphere & it got worse at higher Reynolds numbers &/or when turbulence was introduced. & I reiterate, having multiple smaller cylinders will generate more drag than 1 bigger one.
*Then again, the aerodynamic issue is very much besides the point. The 'original' (subject to the aforementioned caveat) bow wing rigger - the Fluidesign one - is in fact composed of tubes. If the aerodynamic factors aren't advantageous, they can simply be dropped without the essence of the thread - whether having the wing rigger behind you is advantageous ('wing' being used loosely!) - being lost.
As for undue toughness, I have managed mostly to avoid confrontations on the internet, but of the few I've had, this is easily the most cordial, if also the most technical/'inquisitive'. Unfortunately, you expect far more academic rigour than most supervisors do. Indeed, I typically expected far more of myself than my supervisors did; unfortunately, that put me at odds with the vast, impractical volume of work demanded, which was far the more significant/crippling factor - that's why I'm not currently a Cambridge student - the e-mail address is a little misleading. That being the case, I am now freer to travel to races away from the Cam & will be doing so in the near future. I don't think we've nearly exhausted this topic or that this is the best place to continue to discus it - frankly, I need to sleep & my fingers are starting to hurt! I am currently in Sheffield, I indent to race at the York spring regatta & elsewhere. If you're ever in the vicinity, it would be good to discuss this further.
Mike
PS Overall, my point is that the rigger is certainly different; some of the difference may be advantageous - only time will tell!
I wouldn't say I was 'taking the piss' about transonic velocity, but I was semi serious - by your own admission, you 'shouldn't have been attempting maths at bed time,' & it was tangential to the thrust of my post. My point was that the speed of sound through water is rarely worth considering in flow problems. You are quite right about the Russian torpedoes - they are in fact use the super- cavitation which as I mentioned; indeed, that phenomenon occurs (typically) well below the speed of sound in water & renders it moot by surround the body with... 'something other than water!' In either case, the speed of sound is moot. Similarly, the 5mph, is tangential, but it was only a ball park figure (eg. paddling a 1x, as opposed to racing). But it only comes down to what 'the lower end of the transonic region' happens to be; if on the day in question it was 540mph, then '530 below' puts you right in the 8-11mph bracket you mentioned.
Similarly, the analogies are a bit off topic, & you're right in much of what you say, & I am quite aware of most of it too, including power generation, etc. I'm not in any way disparaging of steam power - the Rankine cycle was a proposed subject of mine for a 4th year project & has much potential. My point was that often current technologies are over egged at the expense of underdeveloped alternative - in the case of steam power, steam engines (reciprocating, non-condensing, lacking in feed pumps to lift the pressure up to efficient levels) were allowed to dominate over the British rail way system beyond WWII, gas turbines were ignored until WWII forced people to listen to Frank Whittle & now the likes of Jeremy Clarkson rant about Hybrid cars without any genuine understanding of their operation or benefits. In each case, the preceding technology was well developed, so it was used well beyond a point at which a new alternative could have been superior.
That being said, I hope you're not suggesting that steam power was ever a sensible source of automotive power. Steam power derives it's efficiency, as you said from scale. It is also of significant value in it's ability to use heat at low temperature - nuclear, geothermal, solar-thermal & in particular, gas turbine exhaust (combined cycles). But to be practical it either needs to have a large source of very clean water, or unclean water & space for a condenser - this was never the case in any vehicle apart from ships, & even then space isn't limitless/worthless. It was used when it was, because materials which could tolerate the higher temperatures associated with IC engines, didn't develop until later (the materials/manufacturing methods point which I mentioned). Once these evolved, steam engines, in there Victorian form, were doomed. It is fortunate that the tendencies which prevailed in the rail industry didn't extend to cars, otherwise some of the investment you mentioned might well have been wasted in 'steam cars.'
The same can, unfortunately be said about IC engine. Your quite right - petrol, gas turbine or hybrid, the CURRENT problems are the same. However, gas turbine engines can be made, materials & control subtleties aside, to run on almost any fuel (including hydrogen/synthesised methane) while the hybrid car industry is a means by which electric propulsion systems for cars can be developed - once greener energy takes over (assuming this happens before London, Cardiff, Liverpool, etc. are under water & half of use don't care either way!) such developments are likely to be of much more value than those aimed at eking out every drop from IC engines.
On to the subject at hand. I did say that I hadn't done any analysis. The reason for that, is if I did, especially without being employed to do so, it would risk taking over my life. However, I pride myself on considering my opinions carefully & changing them in the face of suitable evidence. & you're right, what I have said is to an extent an opinion. But all we can say at this point is to an extent opinion. Only time can tell whether bow wing riggers will make boats go faster - I don't think there is a flaw in my reasoning regarding comparison, or that a balanced account can be made of the pro's & cons until this arrangement is developed - compared to other arrangements, you must admit it is in its infancy - I hope your not (& don't think that you are) trying to kill it before it does (develop).
Regarding structures, I think you're over simplifying the matter. The shortest path is not always best. Sometimes, finding the most efficient way to carry a load is more important than a short path - consider a suspension bridge: deck to suspending cables, to main cable, to pier/abutment. It is far from the shortest path, but it is more efficient, because (in this case) a disproportionate amount of load can be carried in pure tension. In the case of the shoulder, just because it is the shortest path, doesn't make it the best, particularly, since the optimum load path in this case (I.e. a straight line though the centroid of the oar loom) is blocked in certain phases of the stroke, leading to the pin pitching issues, torsion, etc. As for distributing loads; in some cases it makes perfect sense to use each part of a system for multiple uses, but there are often penalties to be paid. The main function of the hull is to carry a distributed load of buoyancy & to direct the water. By virtue of being beam-like, it is also suitable for carrying axial & bending loads in certain directions. However, it is not well suited to carrying transverse, 'crushing' loads, which is why the cockpit needs reinforcements simply to support the weight of the rower. Add in the load from the riggers & you soon end up loosing stiffness (over time) - you didn't comment on my point that the bow wing removed the stress from the hull, making it last better (?). As for the washboards, my point was more or less in line with what you're saying - by having the rigger mountings in the bow of the cockpit, they can serve both to do this & deflect water. Other arrangements require the task to be carried out by separate structures. As for focusing the loads, I'm not sure this is an issue - the whole point of the wing rigger is that much of the loads are contained in the rigger & never pas into 'one place' on the hull - only axial forces are transmitted to the hull, which are neither as large or concentrated as those which are developed by multi-stay riggers.
You talk about rigger stiffness - I'm not to sure of the context. To my mind, the critical point about rigger stiffness is the deflection under motive load. In the case of a bow wing, this consists of the bending of the rigger & stretching of the hull. In most analyses, axial extensions are simply ignored, since they are so small. Deflections of beams & triangulated structures are significant & are usually the main components in a structure. In **most** cases, torsional deflections aren't relevant, simply because they 'designed out' & would be overwhelming if they weren't - few structures make significant use of torsional rigidity directly, but conventional & stern wing riggers require all three of the latter. Again, I haven't worked in the field, but it seems probable that it is easier to make a bow wing rigger stiffer in the direction of propulsive force. Vertical stiffness is another issue, but I can't see why it is a big one. However: to the best of my recollection, bending stiffness is proportional to both the width & skin thickness of a (hollow) section, the square of its depth & inversely proportional to the length of the beam. Therefore, a small increase in the section of a wing rigger should easily offset the increase in length compared to the length of a stay. Similarly, as I said, one big wing rigger (even of circular cross section) is likely to produce less drag than many smaller stays of a multi-stay system combined. The big difference in vertical stiffness is that now the bow wing rigger suffers from torsional issues. However, a closed, quasi-elliptical hollow sections would have relatively good torsional properties; given that the section is designed to carry significant propulsive forces, I really can't see how torsional &/or bending stiffness will be a limiting factor when subjected to relatively small vertical loads (???)
The comparisons that I made were such as to express my perspective as clearly as possible, since they do ultimately come down to comparisons with other rigger types. I do concede that they, this & indeed your post are all rather longer than ideal, but that was the best I could do. I'm not sure where you feel I made presumptions, wild or otherwise & I would like to clarify them, but I really don't feel this is the best place. But simply, I would say that 2 stay rigger without top stays need reinforcement in torsion & bending that the addition of a top stay &/or replacement with a bow wing might well supplant :$ In essence, the rigger/rigging could be made lighter. This might not be the case, but without access to the necessary data, any calculations which I might make would similarly be based on assumptions, or at best on designs which as I said, are relatively underdeveloped.
Weight distribution - I'm not fully clear on this. I must say, I could rationalise a reason why having weight at the bow being beneficial, while this I don't think is true of the reverse. But unless I'm mistaken, bow loaded 4+ are acknowledged to be quicker than stern loaded. Any ballast needed to bring a boat up to FISA minimum weight tends to be placed towards the bow. If this is not the case, I stand corrected. If it is, why? & why is it not equally the case for rigging weight?
Pin position - just last week, a GB rowing technical director pointed out that many scullers row much too far behind the pin. In the case of stern wing riggers, this flawed arrangement can make the wing smaller. In the case of a conventional rigger, having the pin behind the shoulder makes the rigger far less efficient - as you said, it's advantage is in having the shortest possible load path, while moving the rib back means that the sculler is more likely to hit it with their hips. Moving the stretcher back would have either the same effect, or prevent the rower from getting their shins vertical at the catch (& surely affect the pitch of the boat - if not other things must be adjusted, in which case everything is moving *except* for the pin! :p). My point wasn't one of boat set up, but that, in general, from a design point of view, having the pin further back is better as it makes setting up the boat to row through the pin easier. More over, having the pin further back with a bow wing rigger makes it more compact, whereas other arrangements are made heavier.
Now, aerodynamics. I must admit, I hadn't didn't considered buffeting & you're quite right about that. Since I am concerned with performance in poor conditions, this is a valid consideration. If you've done extensive testing on riggers, I'd have to yield to your knowledge, at least without being able to look at the data myself. Also, while I am aware of vortex shedding & the fundamentals of how/why it happens, I am not intimately familiar with the phenomenon. However: I wouldn't have said it is ever likely to be an issue with the oar, since it is continuously accelerating. This is not so much the case with the rigger. Also, while aerofoil shapes *can* produce lift, my point was that it is not necessarily the case. Take my example of the E-3 - those aerofoils, or more precisely aerodynamic struts, are intended to generate absolutely no lift. I'm flip flopping slightly here, but in calm conditions, although the air near the water might be turbulent, paradoxically, this doesn't mean it moves up & down all that much! Turbulence is a misunderstood phenomenon & I doubt (in calm conditions) that a wing rigger would produce that much lift.* As for drag, again genuine figures take precedence. However, as a part of my degree, I did an experiment comparing (amongst other things) the drag on a sphere & 'aerodynamic' body of equal diameter. While this is not quite the same as comparing prismatic bodies (like riggers stay/similar) there are solid analogies to be made - the difference in coefficient of drag for Reynolds numbers typical of a rigger were found to be more than twice as high for the sphere & it got worse at higher Reynolds numbers &/or when turbulence was introduced. & I reiterate, having multiple smaller cylinders will generate more drag than 1 bigger one.
*Then again, the aerodynamic issue is very much besides the point. The 'original' (subject to the aforementioned caveat) bow wing rigger - the Fluidesign one - is in fact composed of tubes. If the aerodynamic factors aren't advantageous, they can simply be dropped without the essence of the thread - whether having the wing rigger behind you is advantageous ('wing' being used loosely!) - being lost.
As for undue toughness, I have managed mostly to avoid confrontations on the internet, but of the few I've had, this is easily the most cordial, if also the most technical/'inquisitive'. Unfortunately, you expect far more academic rigour than most supervisors do. Indeed, I typically expected far more of myself than my supervisors did; unfortunately, that put me at odds with the vast, impractical volume of work demanded, which was far the more significant/crippling factor - that's why I'm not currently a Cambridge student - the e-mail address is a little misleading. That being the case, I am now freer to travel to races away from the Cam & will be doing so in the near future. I don't think we've nearly exhausted this topic or that this is the best place to continue to discus it - frankly, I need to sleep & my fingers are starting to hurt! I am currently in Sheffield, I indent to race at the York spring regatta & elsewhere. If you're ever in the vicinity, it would be good to discuss this further.
Mike
PS Overall, my point is that the rigger is certainly different; some of the difference may be advantageous - only time will tell!
Carl
Apr 27, 2012, 10:18:22 AM4/27/12
to
On 27/04/2012 09:20, Mike wrote:
> 1st, I'll say I'm not too clear on everything you're saying, so I'll avoid/query as necessary. I take it that RSR is a forum - I'm not familiar with it, as I came across this thread on Google groups& not anywhere else - you're right, it isn't particularly... 'compact!' Likewise, the delay is purely accidental - I had forgotten the name (Fluidesign) of the company who 'first' (at least recently) manufactured bow wing riggers - the Google search brought me here.
& it was tangential to the thrust of my post. My point was that the
speed of sound through water is rarely worth considering in flow
problems. You are quite right about the Russian torpedoes - they are in
fact use the super- cavitation which as I mentioned; indeed, that
phenomenon occurs (typically) well below the speed of sound in water&
renders it moot by surround the body with... 'something other than
water!' In either case, the speed of sound is moot. Similarly, the 5mph,
is tangential, but it was only a ball park figure (eg. paddling a 1x, as
opposed to racing). But it only comes down to what 'the lower end of the
transonic region' happens to be; if on the day in question it was
540mph, then '530 below' puts you right in the 8-11mph bracket you
mentioned.
>
> Similarly, the analogies are a bit off topic
Not so much off topic as inappropriate & misleading. Good science is
about facts, not loquacious advocacy.
,& you're right in much of what you say,& I am quite aware of most of
remains the predominant cycle in electric power generation world-wide.
My point was that often current technologies are over egged at the
expense of underdeveloped alternative - in the case of steam power,
steam engines (reciprocating, non-condensing, lacking in feed pumps to
lift the pressure up to efficient levels) were allowed to dominate over
the British rail way system beyond WWII, gas turbines were ignored until
WWII forced people to listen to Frank Whittle& now the likes of Jeremy
results. For a period either side of 1900 steam was the medium of
choice for cars (liquid fuelled) & commercial vehicles (liquid & solid
fuelled). And respectable road speed records were set by steam cars,
but the funds followed those avenues promising the earliest progress one
of which was the internal combustion engine.
Please don't confuse efficiency with capacity: steam's efficiency is not
related to size, but the power per volume is. IC engines can be very
compact in power:volume terms, satisfying the excessive demands of
power-hungry motoring & contributing to motoring's vast annual death
toll). Hybrid cars are perhaps a folly, since they carry such a weight
of storage batteries & simply shift their pollution elsewhere - to the
effluents of huge Rankine cycle (steam-powered) generating stations & to
all the electrical distribution-system losses. Green is, in that sense,
mere greenwash.
Power generation by solar, wind, tide & wave can, however, be very
efficient, despite the loud fools tilting at windmills & claiming that
wind is 'inefficient' because the wind doesn't always blow at maximum
strength.
However, rowers are the good guys. Many cycle to their outings & many
train without the accompanying roar of a multi-horsepower engine.
Indeed, why do we need 20hp to carry 1 coach behind a 9-man crew running
on barely 3hp? That really is inefficient!
>
> The same can, unfortunately be said about IC engine. Your quite right - petrol, gas turbine or hybrid, the CURRENT problems are the same. However, gas turbine engines can be made, materials& control subtleties aside, to run on almost any fuel (including hydrogen/synthesised methane) while the hybrid car industry is a means by which electric propulsion systems for cars can be developed - once greener energy takes over (assuming this happens before London, Cardiff, Liverpool, etc. are under water& half of use don't care either way!) such developments are likely to be of much more value than those aimed at eking out every drop from IC engines.
>
> On to the subject at hand. I did say that I hadn't done any analysis. The reason for that, is if I did, especially without being employed to do so, it would risk taking over my life. However, I pride myself on considering my opinions carefully& changing them in the face of suitable evidence.& you're right, what I have said is to an extent an opinion. But all we can say at this point is to an extent opinion. Only time can tell whether bow wing riggers will make boats go faster - I don't think there is a flaw in my reasoning regarding comparison, or that a balanced account can be made of the pro's& cons until this arrangement is developed - compared to other arrangements, you must admit it is in its infancy - I hope your not (& don't think that you are) trying to kill it before it does (develop).
>
> Regarding structures, I think you're over simplifying the matter. The shortest path is not always best. Sometimes, finding the most efficient way to carry a load is more important than a short path - consider a suspension bridge: deck to suspending cables, to main cable, to pier/abutment. It is far from the shortest path, but it is more efficient, because (in this case) a disproportionate amount of load can be carried in pure tension. In the case of the shoulder, just because it is the shortest path, doesn't make it the best, particularly, since the optimum load path in this case (I.e. a straight line though the centroid of the oar loom) is blocked in certain phases of the stroke, leading to the pin pitching issues, torsion, etc. As for distributing loads; in some cases it makes perfect sense to use each part of a system for multiple uses, but there are often penalties to be paid. The main function of the hull is to carry a distributed load of buoyancy& to direct the water. By vi
rtue of being beam-like, it is also suitable for carrying axial& bending loads in certain directions. However, it is not well suited to carrying transverse, 'crushing' loads, which is why the cockpit needs reinforcements simply to support the weight of the rower. Add in the load from the riggers& you soon end up loosing stiffness (over time) - you didn't comment on my point that the bow wing removed the stress from the hull, making it last better (?). As for the washboards, my point was more or less in line with what you're saying - by having the rigger mountings in the bow of the cockpit, they can serve both to do this& deflect water. Other arrangements require the task to be carried out by separate structures. As for focusing the loads, I'm not sure this is an issue - the whole point of the wing rigger is that much of the loads are contained in the rigger& never pas into 'one place' on the hull - only axial forces are transmitted to the hull, which are neither as large or conce
iffness is proportional to both the width& skin thickness of a (hollow) section, the square of its depth& inversely proportional to the length of the beam. Therefore, a small increase in the section of a wing rigger should easily offset the increase in length compared to the length of a stay. Similarly, as I said, one big wing rigger (even of circular cross section) is likely to produce less drag than many smaller stays of a multi-stay system combined. The big difference in vertical stiffness is that now the bow wing rigger suffers from torsional issues. However, a closed, quasi-elliptical hollow sections would have relatively good torsional properties; given that the section is designed to carry significant propulsive forces, I really can't see how torsional&/or bending stiffness will be a limiting factor when subjected to relatively small vertical loads (???)
>
> The comparisons that I made were such as to express my perspective as clearly as possible, since they do ultimately come down to comparisons with other rigger types. I do concede that they, this& indeed your post are all rather longer than ideal, but that was the best I could do. I'm not sure where you feel I made presumptions, wild or otherwise& I would like to clarify them, but I really don't feel this is the best place. But simply, I would say that 2 stay rigger without top stays need reinforcement in torsion& bending that the addition of a top stay&/or replacement with a bow wing might well supplant :$ In essence, the rigger/rigging could be made lighter. This might not be the case, but without access to the necessary data, any calculations which I might make would similarly be based on assumptions, or at best on designs which as I said, are relatively underdeveloped.
>
> Weight distribution - I'm not fully clear on this. I must say, I could rationalise a reason why having weight at the bow being beneficial, while this I don't think is true of the reverse. But unless I'm mistaken, bow loaded 4+ are acknowledged to be quicker than stern loaded. Any ballast needed to bring a boat up to FISA minimum weight tends to be placed towards the bow. If this is not the case, I stand corrected. If it is, why?& why is it not equally the case for rigging weight?
'over-simplify', as you put it. The well-made boat & its rigging should
be designed around the physical needs of the competitive sculler, the
laws of hydrodynamics & the science of structural engineering, so you
are clutching at straws. When you feel the urge to make an airy claim,
please avoid the use of patronising presumption & hyperbole. And please
don't presume to treat those of us who do the real work in this field, &
spend a fair bit of time explaining what we do in such places as RSR, as
complete fools.
Moving the stretcher back would have either the same effect, or
prevent the rower from getting their shins vertical at the catch
Ah! that old vertical shins myth raises its ugly head yet again. The
alignment of the shins is a consequence of individual & variable human
geometry as well as of stretcher/seat relationship but in no way defines
whether a catch position is strong or not. It's what folk coach for
after hearing someone else coach for it, which adds gravitas to a
frankly meaningless perception.
(& surely affect the pitch of the boat - if not other things must be
adjusted, in which case everything is moving *except* for the pin! :p).
My point wasn't one of boat set up, but that, in general, from a design
point of view, having the pin further back is better as it makes setting
up the boat to row through the pin easier. More over, having the pin
further back with a bow wing rigger makes it more compact, whereas other
arrangements are made heavier.
>
> Now, aerodynamics. I must admit, I hadn't didn't considered buffeting& you're quite right about that. Since I am concerned with performance in poor conditions, this is a valid consideration. If you've done extensive testing on riggers, I'd have to yield to your knowledge, at least without being able to look at the data myself. Also, while I am aware of vortex shedding& the fundamentals of how/why it happens, I am not intimately familiar with the phenomenon. However: I wouldn't have said it is ever likely to be an issue with the oar, since it is continuously accelerating. This is not so much the case with the rigger. Also, while aerofoil shapes *can* produce lift, my point was that it is not necessarily the case. Take my example of the E-3 - those aerofoils, or more precisely aerodynamic struts, are intended to generate absolutely no lift. I'm flip flopping slightly here, but in calm conditions, although the air near the water might be turbulent, paradoxically, this doesn't mean
it moves up& down all that much! Turbulence is a misunderstood phenomenon& I doubt (in calm conditions) that a wing rigger would produce that much lift.* As for drag, again genuine figures take precedence. However, as a part of my degree, I did an experiment comparing (amongst other things) the drag on a sphere& 'aerodynamic' body of equal diameter. While this is not quite the same as comparing prismatic bodies (like riggers stay/similar) there are solid analogies to be made - the difference in coefficient of drag for Reynolds numbers typical of a rigger were found to be more than twice as high for the sphere& it got worse at higher Reynolds numbers&/or when turbulence was introduced.& I reiterate, having multiple smaller cylinders will generate more drag than 1 bigger one.
treated as irrelevant by most in rowing. That's probably because it's
easier to say "Its the same for all" than to engage the brain.
>
> As for undue toughness, I have managed mostly to avoid confrontations on the internet, but of the few I've had, this is easily the most cordial, if also the most technical/'inquisitive'. Unfortunately, you expect far more academic rigour than most supervisors do. Indeed, I typically expected far more of myself than my supervisors did; unfortunately, that put me at odds with the vast, impractical volume of work demanded, which was far the more significant/crippling factor - that's why I'm not currently a Cambridge student - the e-mail address is a little misleading. That being the case, I am now freer to travel to races away from the Cam& will be doing so in the near future. I don't think we've nearly exhausted this topic or that this is the best place to continue to discus it - frankly, I need to sleep& my fingers are starting to hurt! I am currently in Sheffield, I indent to race at the York spring regatta& elsewhere. If you're ever in the vicinity, it would be good to discuss
this further.
In good Usenet tradition (& any normal email browser - e.g Thunderbird -
can download Usenet groups & properly thread discussions when correctly
configured) on RSR we try to talk straight, from the heart & to the
point without prissy PC nonsense. This is not a confrontation but it is
clearly an area in which you & I may somewhat disagree, & both may learn
(although I, like my grandmother, may already know how to suck eggs).
Cheers -
Carl
> 1st, I'll say I'm not too clear on everything you're saying, so I'll avoid/query as necessary. I take it that RSR is a forum - I'm not familiar with it, as I came across this thread on Google groups& not anywhere else - you're right, it isn't particularly... 'compact!' Likewise, the delay is purely accidental - I had forgotten the name (Fluidesign) of the company who 'first' (at least recently) manufactured bow wing riggers - the Google search brought me here.
>
> I wouldn't say I was 'taking the piss' about transonic velocity, but I was semi serious - by your own admission, you 'shouldn't have been attempting maths at bed time,'
That may be true, but it has never stopped me ;)
> I wouldn't say I was 'taking the piss' about transonic velocity, but I was semi serious - by your own admission, you 'shouldn't have been attempting maths at bed time,'
& it was tangential to the thrust of my post. My point was that the
speed of sound through water is rarely worth considering in flow
problems. You are quite right about the Russian torpedoes - they are in
fact use the super- cavitation which as I mentioned; indeed, that
phenomenon occurs (typically) well below the speed of sound in water&
renders it moot by surround the body with... 'something other than
water!' In either case, the speed of sound is moot. Similarly, the 5mph,
is tangential, but it was only a ball park figure (eg. paddling a 1x, as
opposed to racing). But it only comes down to what 'the lower end of the
transonic region' happens to be; if on the day in question it was
540mph, then '530 below' puts you right in the 8-11mph bracket you
mentioned.
>
> Similarly, the analogies are a bit off topic
about facts, not loquacious advocacy.
,& you're right in much of what you say,& I am quite aware of most of
it too, including power generation, etc. I'm not in any way disparaging
of steam power - the Rankine cycle was a proposed subject of mine for a
4th year project& has much potential.
Indeed, the Rankine cycle has so much potential that has long been &
of steam power - the Rankine cycle was a proposed subject of mine for a
4th year project& has much potential.
remains the predominant cycle in electric power generation world-wide.
My point was that often current technologies are over egged at the
expense of underdeveloped alternative - in the case of steam power,
steam engines (reciprocating, non-condensing, lacking in feed pumps to
lift the pressure up to efficient levels) were allowed to dominate over
the British rail way system beyond WWII, gas turbines were ignored until
Clarkson rant about Hybrid cars without any genuine understanding of
their operation or benefits. In each case, the preceding technology was
well developed, so it was used well beyond a point at which a new
alternative could have been superior.
>
> That being said, I hope you're not suggesting that steam power was ever a sensible source of automotive power. Steam power derives it's efficiency, as you said from scale. It is also of significant value in it's ability to use heat at low temperature - nuclear, geothermal, solar-thermal& in particular, gas turbine exhaust (combined cycles). But to be practical it either needs to have a large source of very clean water, or unclean water& space for a condenser - this was never the case in any vehicle apart from ships,& even then space isn't limitless/worthless. It was used when it was, because materials which could tolerate the higher temperatures associated with IC engines, didn't develop until later (the materials/manufacturing methods point which I mentioned). Once these evolved, steam engines, in there Victorian form, were doomed. It is fortunate that the tendencies which prevailed in the rail industry didn't extend to cars, otherwise some of the investment you mentioned migh
their operation or benefits. In each case, the preceding technology was
well developed, so it was used well beyond a point at which a new
alternative could have been superior.
>
t well have been wasted in 'steam cars.'
Actually, investment in development is rarely wasted if new knowledge
results. For a period either side of 1900 steam was the medium of
choice for cars (liquid fuelled) & commercial vehicles (liquid & solid
fuelled). And respectable road speed records were set by steam cars,
but the funds followed those avenues promising the earliest progress one
of which was the internal combustion engine.
Please don't confuse efficiency with capacity: steam's efficiency is not
related to size, but the power per volume is. IC engines can be very
compact in power:volume terms, satisfying the excessive demands of
power-hungry motoring & contributing to motoring's vast annual death
toll). Hybrid cars are perhaps a folly, since they carry such a weight
of storage batteries & simply shift their pollution elsewhere - to the
effluents of huge Rankine cycle (steam-powered) generating stations & to
all the electrical distribution-system losses. Green is, in that sense,
mere greenwash.
Power generation by solar, wind, tide & wave can, however, be very
efficient, despite the loud fools tilting at windmills & claiming that
wind is 'inefficient' because the wind doesn't always blow at maximum
strength.
However, rowers are the good guys. Many cycle to their outings & many
train without the accompanying roar of a multi-horsepower engine.
Indeed, why do we need 20hp to carry 1 coach behind a 9-man crew running
on barely 3hp? That really is inefficient!
>
> The same can, unfortunately be said about IC engine. Your quite right - petrol, gas turbine or hybrid, the CURRENT problems are the same. However, gas turbine engines can be made, materials& control subtleties aside, to run on almost any fuel (including hydrogen/synthesised methane) while the hybrid car industry is a means by which electric propulsion systems for cars can be developed - once greener energy takes over (assuming this happens before London, Cardiff, Liverpool, etc. are under water& half of use don't care either way!) such developments are likely to be of much more value than those aimed at eking out every drop from IC engines.
>
> On to the subject at hand. I did say that I hadn't done any analysis. The reason for that, is if I did, especially without being employed to do so, it would risk taking over my life. However, I pride myself on considering my opinions carefully& changing them in the face of suitable evidence.& you're right, what I have said is to an extent an opinion. But all we can say at this point is to an extent opinion. Only time can tell whether bow wing riggers will make boats go faster - I don't think there is a flaw in my reasoning regarding comparison, or that a balanced account can be made of the pro's& cons until this arrangement is developed - compared to other arrangements, you must admit it is in its infancy - I hope your not (& don't think that you are) trying to kill it before it does (develop).
>
> Regarding structures, I think you're over simplifying the matter. The shortest path is not always best. Sometimes, finding the most efficient way to carry a load is more important than a short path - consider a suspension bridge: deck to suspending cables, to main cable, to pier/abutment. It is far from the shortest path, but it is more efficient, because (in this case) a disproportionate amount of load can be carried in pure tension. In the case of the shoulder, just because it is the shortest path, doesn't make it the best, particularly, since the optimum load path in this case (I.e. a straight line though the centroid of the oar loom) is blocked in certain phases of the stroke, leading to the pin pitching issues, torsion, etc. As for distributing loads; in some cases it makes perfect sense to use each part of a system for multiple uses, but there are often penalties to be paid. The main function of the hull is to carry a distributed load of buoyancy& to direct the water. By vi
rtue of being beam-like, it is also suitable for carrying axial& bending loads in certain directions. However, it is not well suited to carrying transverse, 'crushing' loads, which is why the cockpit needs reinforcements simply to support the weight of the rower. Add in the load from the riggers& you soon end up loosing stiffness (over time) - you didn't comment on my point that the bow wing removed the stress from the hull, making it last better (?). As for the washboards, my point was more or less in line with what you're saying - by having the rigger mountings in the bow of the cockpit, they can serve both to do this& deflect water. Other arrangements require the task to be carried out by separate structures. As for focusing the loads, I'm not sure this is an issue - the whole point of the wing rigger is that much of the loads are contained in the rigger& never pas into 'one place' on the hull - only axial forces are transmitted to the hull, which are neither as large or conce
ntrated as those which are developed by multi-stay riggers.
>
> You talk about rigger stiffness - I'm not to sure of the context. To my mind, the critical point about rigger stiffness is the deflection under motive load. In the case of a bow wing, this consists of the bending of the rigger& stretching of the hull. In most analyses, axial extensions are simply ignored, since they are so small. Deflections of beams& triangulated structures are significant& are usually the main components in a structure. In **most** cases, torsional deflections aren't relevant, simply because they 'designed out'& would be overwhelming if they weren't - few structures make significant use of torsional rigidity directly, but conventional& stern wing riggers require all three of the latter. Again, I haven't worked in the field, but it seems probable that it is easier to make a bow wing rigger stiffer in the direction of propulsive force. Vertical stiffness is another issue, but I can't see why it is a big one. However: to the best of my recollection, bending st
>
iffness is proportional to both the width& skin thickness of a (hollow) section, the square of its depth& inversely proportional to the length of the beam. Therefore, a small increase in the section of a wing rigger should easily offset the increase in length compared to the length of a stay. Similarly, as I said, one big wing rigger (even of circular cross section) is likely to produce less drag than many smaller stays of a multi-stay system combined. The big difference in vertical stiffness is that now the bow wing rigger suffers from torsional issues. However, a closed, quasi-elliptical hollow sections would have relatively good torsional properties; given that the section is designed to carry significant propulsive forces, I really can't see how torsional&/or bending stiffness will be a limiting factor when subjected to relatively small vertical loads (???)
>
> The comparisons that I made were such as to express my perspective as clearly as possible, since they do ultimately come down to comparisons with other rigger types. I do concede that they, this& indeed your post are all rather longer than ideal, but that was the best I could do. I'm not sure where you feel I made presumptions, wild or otherwise& I would like to clarify them, but I really don't feel this is the best place. But simply, I would say that 2 stay rigger without top stays need reinforcement in torsion& bending that the addition of a top stay&/or replacement with a bow wing might well supplant :$ In essence, the rigger/rigging could be made lighter. This might not be the case, but without access to the necessary data, any calculations which I might make would similarly be based on assumptions, or at best on designs which as I said, are relatively underdeveloped.
>
> Weight distribution - I'm not fully clear on this. I must say, I could rationalise a reason why having weight at the bow being beneficial, while this I don't think is true of the reverse. But unless I'm mistaken, bow loaded 4+ are acknowledged to be quicker than stern loaded. Any ballast needed to bring a boat up to FISA minimum weight tends to be placed towards the bow. If this is not the case, I stand corrected. If it is, why?& why is it not equally the case for rigging weight?
>
> Pin position - just last week, a GB rowing technical director pointed out that many scullers row much too far behind the pin. In the case of stern wing riggers, this flawed arrangement can make the wing smaller. In the case of a conventional rigger, having the pin behind the shoulder makes the rigger far less efficient - as you said, it's advantage is in having the shortest possible load path, while moving the rib back means that the sculler is more likely to hit it with their hips.
Most of that is, I regret to say, just nonsensical. And I never
> Pin position - just last week, a GB rowing technical director pointed out that many scullers row much too far behind the pin. In the case of stern wing riggers, this flawed arrangement can make the wing smaller. In the case of a conventional rigger, having the pin behind the shoulder makes the rigger far less efficient - as you said, it's advantage is in having the shortest possible load path, while moving the rib back means that the sculler is more likely to hit it with their hips.
'over-simplify', as you put it. The well-made boat & its rigging should
be designed around the physical needs of the competitive sculler, the
laws of hydrodynamics & the science of structural engineering, so you
are clutching at straws. When you feel the urge to make an airy claim,
please avoid the use of patronising presumption & hyperbole. And please
don't presume to treat those of us who do the real work in this field, &
spend a fair bit of time explaining what we do in such places as RSR, as
complete fools.
Moving the stretcher back would have either the same effect, or
prevent the rower from getting their shins vertical at the catch
alignment of the shins is a consequence of individual & variable human
geometry as well as of stretcher/seat relationship but in no way defines
whether a catch position is strong or not. It's what folk coach for
after hearing someone else coach for it, which adds gravitas to a
frankly meaningless perception.
(& surely affect the pitch of the boat - if not other things must be
adjusted, in which case everything is moving *except* for the pin! :p).
My point wasn't one of boat set up, but that, in general, from a design
point of view, having the pin further back is better as it makes setting
up the boat to row through the pin easier. More over, having the pin
further back with a bow wing rigger makes it more compact, whereas other
arrangements are made heavier.
>
it moves up& down all that much! Turbulence is a misunderstood phenomenon& I doubt (in calm conditions) that a wing rigger would produce that much lift.* As for drag, again genuine figures take precedence. However, as a part of my degree, I did an experiment comparing (amongst other things) the drag on a sphere& 'aerodynamic' body of equal diameter. While this is not quite the same as comparing prismatic bodies (like riggers stay/similar) there are solid analogies to be made - the difference in coefficient of drag for Reynolds numbers typical of a rigger were found to be more than twice as high for the sphere& it got worse at higher Reynolds numbers&/or when turbulence was introduced.& I reiterate, having multiple smaller cylinders will generate more drag than 1 bigger one.
>
> *Then again, the aerodynamic issue is very much besides the point. The 'original' (subject to the aforementioned caveat) bow wing rigger - the Fluidesign one - is in fact composed of tubes. If the aerodynamic factors aren't advantageous, they can simply be dropped without the essence of the thread - whether having the wing rigger behind you is advantageous ('wing' being used loosely!) - being lost.
Aerodynamics is _never_ irrelevant in rowing but it certainly gets
> *Then again, the aerodynamic issue is very much besides the point. The 'original' (subject to the aforementioned caveat) bow wing rigger - the Fluidesign one - is in fact composed of tubes. If the aerodynamic factors aren't advantageous, they can simply be dropped without the essence of the thread - whether having the wing rigger behind you is advantageous ('wing' being used loosely!) - being lost.
treated as irrelevant by most in rowing. That's probably because it's
easier to say "Its the same for all" than to engage the brain.
>
> As for undue toughness, I have managed mostly to avoid confrontations on the internet, but of the few I've had, this is easily the most cordial, if also the most technical/'inquisitive'. Unfortunately, you expect far more academic rigour than most supervisors do. Indeed, I typically expected far more of myself than my supervisors did; unfortunately, that put me at odds with the vast, impractical volume of work demanded, which was far the more significant/crippling factor - that's why I'm not currently a Cambridge student - the e-mail address is a little misleading. That being the case, I am now freer to travel to races away from the Cam& will be doing so in the near future. I don't think we've nearly exhausted this topic or that this is the best place to continue to discus it - frankly, I need to sleep& my fingers are starting to hurt! I am currently in Sheffield, I indent to race at the York spring regatta& elsewhere. If you're ever in the vicinity, it would be good to discuss
this further.
In good Usenet tradition (& any normal email browser - e.g Thunderbird -
can download Usenet groups & properly thread discussions when correctly
configured) on RSR we try to talk straight, from the heart & to the
point without prissy PC nonsense. This is not a confrontation but it is
clearly an area in which you & I may somewhat disagree, & both may learn
(although I, like my grandmother, may already know how to suck eggs).
Cheers -
Carl
>
> Mike
>
> PS Overall, my point is that the rigger is certainly different; some of the difference may be advantageous - only time will tell!
> Mike
>
> PS Overall, my point is that the rigger is certainly different; some of the difference may be advantageous - only time will tell!
pmhor...@gmail.com
Dec 30, 2015, 4:15:24 PM12/30/15
to
On Friday, February 19, 2010 at 4:15:32 AM UTC-5, Rob Purves wrote:
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage? Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
Have any Bow mounted riggers won any national championships or olympics?
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage? Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
gsl...@gmail.com
Dec 30, 2015, 9:00:57 PM12/30/15
to
You can make good and bad designs in every type of rigger. Yes bow mounted riggers are longer and heavier and the shape is often more complex.
It all comes down how well the any given design is engineered.
The rigger type will matters in some collisions, and in the relative difficulty in getting back into the boat.
Anyone who tells you one type of rigger is faster than another with reference to specific design is talking through their ass.
Chip Johannessen
Dec 31, 2015, 12:14:37 AM12/31/15
to
Take a look at the London Olympics mens single scull finals. 6 out of 6 are using bow mounted wing riggers, that's a pretty clear consensus.
Kit Davies
Dec 31, 2015, 3:38:40 AM12/31/15
to
On 31/12/2015 05:14, Chip Johannessen wrote:
> Take a look at the London Olympics mens single scull finals. 6 out of 6 are using bow mounted wing riggers, that's a pretty clear consensus.
>
Of what though? That the design is better or that rowers and coaches are
> Take a look at the London Olympics mens single scull finals. 6 out of 6 are using bow mounted wing riggers, that's a pretty clear consensus.
>
sheep?
If there was a statistically significant step-change in winning times,
I'd be a believer. But there hasn't, just as there hasn't been for:
1. Stern-mounted wings
2. Batlogic shoes
2. Fat2s
3. Hatchets
4. Sliding riggers
5. Carbonfibre hulls
So I reckon rowers & coaches are pathological herd followers instead. I
suppose that has benefits. If everyone is using the same equipment,
there can be no question of unfair advantage. But it would be nice to
see at least a few people break the mould a bit.
Kit
carl
Dec 31, 2015, 6:29:30 AM12/31/15
to
Let's start by correcting the OP's statement. Races are won by rowers,
not by equipment. So no riggers "won" anything.
Then let's ask the essential question: why might any particular design
of, say, bow-mounted rigger contribute in any way to improved performance?
Unlike in high-performance sailing, where the relevant physical sciences
really matter & are understood, rowing equipment selection is very
largely fashion-driven & equipment is almost never methodically evaluated.
In the old days of main-frame computers the saying among IT managers
was, "You won't get sacked for buying IBM". Same story for coaches in
rowing: if you use equipment different from the rest & your crew "only"
come 2nd, then clearly you made the wrong choice & get the push; if you
use the same kit as the rest of the bunch & finish 4th, you made no
mistakes & keep your job.
Cheers, & a very successful 2016 to all -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells
Henry Law
Dec 31, 2015, 10:50:24 AM12/31/15
to
On 31/12/15 05:14, Chip Johannessen wrote:
> 6 out of 6 are using bow mounted wing riggers, that's a pretty clear consensus.
Are "conventional" riggers easily available? We keep being told that we
> 6 out of 6 are using bow mounted wing riggers, that's a pretty clear consensus.
are in an age of endless choice, but when it comes down to it one often
finds that one has no choice at all other than something trivial like
colours, because all the manufacturers are turning out the same basic
product. Examples: luggage; laptops; various categories of sports
equipment.
--
Henry Law Manchester, England
gsl...@gmail.com
Dec 31, 2015, 12:05:03 PM12/31/15
to
On Wednesday, December 30, 2015 at 6:00:57 PM UTC-8, gsl...@gmail.com wrote:
> Anyone who tells you one type of rigger is faster than another with reference to specific design is talking through their ass.
That should have read "...without reference to a specific design..."
> Anyone who tells you one type of rigger is faster than another with reference to specific design is talking through their ass.
s...@ku.edu
Dec 31, 2015, 2:05:37 PM12/31/15
to
Steven M-M
Henry Law
Dec 31, 2015, 3:06:22 PM12/31/15
to
On 31/12/15 19:05, s...@ku.edu wrote:
> I believe that Empacher now offers only 3 choices: the carbon and aluminum stern wing and the carbon bow wing
My case rests. Given the scientifically-proven fact that yellow boats
> I believe that Empacher now offers only 3 choices: the carbon and aluminum stern wing and the carbon bow wing
go faster, if you want one you must also grow wings.
Jim Dwyer
Dec 31, 2015, 8:05:56 PM12/31/15
to
I believe that Empacher now offers only 3 choices: the carbon and aluminum
stern wing and the carbon bow wing.
Steven M-M
Jim
gsl...@gmail.com
Dec 31, 2015, 8:20:39 PM12/31/15
to
Who is still offering both wing and traditional riggers besides Chinese manufacturers such as Swift? It is a headache having so many options so why bother if you are not going to make more money?
There are reasons to do things besides pure boat speed.
I would guess that wing riggers and Carbon Fiber hulls simplify manufacturing.
Hatchet blades are easier to row with than Macons.Some people just like the feel of Fat2's.
Bat logic shoes are nice but frankly once I'm in a boat I can't tell any differ. Really don't see any advantage.
s...@ku.edu
Jan 1, 2016, 9:25:22 AM1/1/16
to
At the Hooch, I got a close look at Hudson's new carbon bow wing, a beautiful design. Are you tempted?
Steven M-M
Jim Dwyer
Jan 1, 2016, 10:38:23 AM1/1/16
to
Yes! They are nice and they weigh less than the aluminum riggers.
I am shopping for a boat (I have a mid+ and I am looking for a mid)
Jim
wrote in message
news:34712fe7-298b-45cd...@googlegroups.com...
I am shopping for a boat (I have a mid+ and I am looking for a mid)
Jim
wrote in message
news:34712fe7-298b-45cd...@googlegroups.com...
SingleMinded
Jan 3, 2016, 1:47:48 PM1/3/16
to
On Friday, 1 January 2016 01:20:39 UTC, gsl...@gmail.com wrote:
>
> Who is still offering both wing and traditional riggers besides Chinese manufacturers such as Swift? It is a headache having so many options so why bother if you are not going to make more money?
>
Filippi I think do. I've certainly seen new-ish Filippis with both, and they advertise both on their website.
>
> Who is still offering both wing and traditional riggers besides Chinese manufacturers such as Swift? It is a headache having so many options so why bother if you are not going to make more money?
>
tret...@gmail.com
Jan 27, 2016, 5:37:39 AM1/27/16
to
-Aluminium 3-stay
-Aluminium stern wing
-Aluminium bow wing (My choice)
-Carbon 2-stay tubular
-Carbon stern wing
-Carbon bow wing (Aliante)
My preference came from the cleanliness you feel and how "naked" you are at the front end. It starts off strange but makes you feel the boat a lot more as you have less reference points and has overall made me better technically I feel. As for aluminium over carbon I was instructed to by the UK rep. as I am still a junior (J18) the stiffness of carbon could increase chances of stress fracture injuries, that and given how often I travel with my boat the delicate carbon wing rigger would be far too stressful to keep worrying about.
That being said I have rowed both a Filippi 1x and 2x with the carbon bow (Aliante) option and have to say I feel minimum difference apart from the weight of the rigger is about half that of the aluminium equivalent. That and they make a more satisfying "clunk" when you power through to the finish and feather as is my rowing style.
I know I'm probably quite inexperienced in my broadness of boats used over the years due to my age but train in a high performance group and on the fringes of GB so scull to a high standard and have put many hours into wing rigged (bow or stern) boats in particular.
Toby
gsl...@gmail.com
Jan 28, 2016, 2:58:55 PM1/28/16
to
On Wednesday, January 27, 2016 at 2:37:39 AM UTC-8, tret...@gmail.com wrote:
.... As for aluminium over carbon I was instructed to by the UK rep. as I am still a junior (J18) the stiffness of carbon could increase chances of stress fracture injuries ...
Surprised at this. I would think that the flexibility of the oar would dominate. Would be interesting to measure how much the rigger bends vs the oar to see if it really mattered.
.... As for aluminium over carbon I was instructed to by the UK rep. as I am still a junior (J18) the stiffness of carbon could increase chances of stress fracture injuries ...
Surprised at this. I would think that the flexibility of the oar would dominate. Would be interesting to measure how much the rigger bends vs the oar to see if it really mattered.
carl
Jan 29, 2016, 1:34:29 PM1/29/16
to
I see this as part of the mythologising process, like the myth that
faster boats must be harder to row. Fashioning an aura of
unattainability by suggesting added difficulty such that only the finest
can handle this delicate instrument is just one way to persuade a fairly
good rower that they must eventually have this or that bit of kit if
they are ever to become a top-flight racer.
To be fair, some of these memes start from within the rowing community
rather than from the salespersons.
May I gently suggest that someone has a poor understanding of
engineering structures? We build 2-stay "conventional" riggers
(AeRoWing™) which, being triangulated structures mounted rigidly to the
boat's internal shoulders (AKA "knees" in other lands) are far stiffer
than any wing rigger that's yet been made, but I've never heard anyone
complain of suffering stress fractures due to our riggers' extreme rigidity.
A wing rigger is always a cantilever (single strut) of small
cross-section & thus inherently rather flexible, like an oarshaft. The
closer that rigger's plan (overhead) view is to a broad triangle, the
stiffer it is for loads applied at its tip in the horizontal plane.
Conversely, the longer it is the disproportionately more flexible it
becomes. Wing riggers are rather narrow for their length, for if they
were not they'd become aerodynamic lifting surfaces with undesirable
consequences (a rigger that generates lift does not reduce hull or
aerodynamic drag but does mess with your balance on windy days).
A triangulated rigger (one stay perpendicular to the boat, one at about
45-deg astern or ahead) has the shorter stay in compression & the longer
stay in tension, creating the broad-triangle plan-view. For the loads
applied & the amount of material used you can't make stiffer or stronger
structure. Yet, as I say, it causes no stress fractures.
Cheers -
roc...@gmail.com
Jan 29, 2016, 2:29:42 PM1/29/16
to
A bow-mounted wing rigger gives easier access to adjust the foot stretcher and shoes. Having no ribs allows wider tracks placement which can mitigate track-bites on the calves. Having no ribs allows hippier rowers to enjoy a narrow boat.
Ian
Ian
carl
Jan 29, 2016, 5:10:13 PM1/29/16
to
On 29/01/2016 19:29, roc...@gmail.com wrote:
> A bow-mounted wing rigger gives easier access to adjust the foot stretcher and shoes. Having no ribs allows wider tracks placement which can mitigate track-bites on the calves. Having no ribs allows hippier rowers to enjoy a narrow boat.
>
> Ian
>
A few comments:
> A bow-mounted wing rigger gives easier access to adjust the foot stretcher and shoes. Having no ribs allows wider tracks placement which can mitigate track-bites on the calves. Having no ribs allows hippier rowers to enjoy a narrow boat.
>
> Ian
>
1. Well-designed track ends do not inflict track-bites. Track bites are
certainly undesirable and present a constant risk of blood-borne
cross-infection where boats are used by multiple crews.
2. The shoulders in well-designed boats do not impede the passage of
even the most shapely and curved of rumps.
3. Stretcher adjustment is certainly impeded by stern-mounted wing
riggers in singles. But bow-mounted wings overhang stretchers in crew boats
tret...@gmail.com
Feb 9, 2016, 5:43:22 AM2/9/16
to
David Cormack
Mar 8, 2016, 5:37:36 AM3/8/16
to
On Friday, 19 February 2010 09:15:32 UTC, Rob Purves wrote:
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage? Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
CAn we not just all agree that really it is aesthetics that is the difference between the different types of riggers?
> Any ideas on why this Empacher design (wing-rigger mounted in the bow
> behind the sculler) http://www.empacher.com/rennboote/Einer_e.html is
> thought to confer an advantage? Looks to me like the rigger would be
> longer and more complex in shape (and so possibly heavier) than a
> standard wing rigger. I note that the lady in the picture looks
> faintly embarrassed... Its nowhere near April 1, yet. Perhaps its
> left over from last year?
>
> Rob
Personally, I think there is no better looking set up than a carbon two stay rigger mounted on the middle and backstops ribs. The best thing about this set up is that they fold up and slip nicely into the boot of the car!
Good luck getting two bow mounted wing rigs into the boot of a car!!
0 new messages