carl

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Jul 4, 2015, 5:00:45 PM7/4/15

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Cat - please try to remember that the load you feel is simply the load
that you decide to apply. So if you row longer then lighten up, let the
stroke finish when it will & certainly don't try to bully it through as
that can only lead to you blowing yourself up.

Also, we rowers & sculler talk far too much about gearing, especially
when you consider how trivial are the changes we can claim to make by
relatively small adjustments to inboard, overall length & spread.

As rowers, we willingly trap ourselves into preconceived notions of
proper lengths, proper rates, proper depths, proper gearing & so on,
while completely forgetting that a gentle head wind has a far greater
effect on stroke duration (if we row the same length), & thus on
apparent gearing, than any of these supposed gearing changes.

So, take as much of Walter's excellent advice as you can manage at any
time, & pull only as hard as makes sense. Do nothing to prematurely
terminate each stroke (but nothing to arbitrarily lengthen each finish).
Be comfortable with how you row, & then gradually explore its outer
limits - remembering always that the longer stroke really is more
efficient, that it must also take longer to complete, that pulling
harder will barely change this & that rating comes largely from the
speed of the middle part of your recovery & from how little time you
waste over the catch.

Above all, don't over-analyse in your search for perfection. Every day
you go afloat you will be a somewhat different person, so your rowing
will sometimes feel great, & sometimes will feel crappy. Take a relaxed
view, get a good feeling & enjoy it.

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: tinyurl.com/2tqujf
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

Charles Carroll

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Jul 5, 2015, 3:26:40 PM7/5/15

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> The load you feel is simply the load that you decide to apply.

> So if you row longer then lighten up, let the stroke finish when
> it will & certainly don't try to bully it through as that can only

> lead to your blowing yourself up.
> Also, we rowers & scullers talk far too much about gearing

> especially when you consider how trivial are the changes
> we can claim to make by relatively small adjustments to
> inboard, overall length & spread.
> As rowers, we willingly trap ourselves into preconceived notions
> of proper lengths, proper rates, proper depths, proper gearing &
> so on, while completely forgetting that a gentle head wind has a far
> greater effect on stroke duration (if we row the same length), & thus
> on apparent gearing, than any of these supposed gearing changes.

> So … pull only as hard as makes sense. Do nothing to prematurely terminate

> each stroke (but nothing to arbitrarily lengthen each finish).
> Be comfortable with how you row, & then gradually explore its outer

> limits — remembering always that the longer stroke really is more

> efficient, that it must also take longer to complete, that pulling harder
> will barely change this & that rating comes largely from the speed of
> the middle part of your recovery & from how little time you waste
> over the catch.
> Above all, don't over-analyse in your search for perfection. Every day
> you go afloat you will be a somewhat different person, so your rowing
> will sometimes feel great, & sometimes will feel crappy. Take a relaxed
> view, get a good feeling & enjoy it

Cat –

This is some of the best advice I have ever read from Carl. I do not know
how it could be said more clearly.

Cut it out. Put it on your wall. And then go out and enjoy your sculling.

Carol Dailey

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Jul 5, 2015, 7:49:19 PM7/5/15

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Okay, and I'm going to call most of these responses a complete load of hooey. For people that pride yourselves on all things scientific and eschewing the regurgitated claptrap that passes for good advice, REALLY? Oh, little girl, just don't row so hard! Forget gearing, forget inboard and outboard, don't worry your little head with numbers. Just enjoy your sculling.

Thank goodness I raced today. I was afraid some of this might have rubbed off. Oh, and after I raced and worked the docks all day, I went and rowed for another 80 minutes just for emphasis.

Regards,

Cat

carl

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Jul 5, 2015, 9:02:33 PM7/5/15

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Wow! You could have someone's eye out with a strop like that. Unless
I've completely misunderstood your meaning & intent, in which case
please correct me.

What you've missed is the message that much of that "magic rigging
maths" stuff is pure invention, its basis in science invalidated by the
variables it ignores. Your conviction will not validate it as science
deals only in facts.

If you're sure, despite seeking advice here, that good rowing demands
slavish adherence to formulae, & that what others have learned over a
lifetime in fluid dynamics, in rowing, in sculling, in applying science
to the dynamics of oared & paddled propulsion & in helping rowers of all
abilities is, to quote you, "a complete load of hooey" - well, that's
your privilege.

I'm trying to allow for my having spent 10 hours today working under a
total power cut in order to complete a boat for export shipment by
lunchtime today, Monday. It's 01:45 as I write because, thanks to the
ineptitude of the power network's managers (who have also been fiddling
their recorded response timings to meet targets), a job their engineers
say should have taken just 2 hours became a marathon cock-up. Having
now finished my coffee, I must work right through the night. Even so,
I'm unimpressed by your response.

We must each have better things to do. Certainly I have.

Charles Carroll

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Jul 5, 2015, 9:25:26 PM7/5/15

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Cat –

All I will add to what Carl has said is that I have known Carl for a number
of years, own one of his magnificent shells, and consider him a good friend.
In all this time I have never known Carl Douglas to be patronizing.

Carl’s advice to you is superb. What’s more, it is consistent with what Carl
has been saying to people for years — and by “people” I mean rowers and
scullers and coaches and anyone else who reads and posts on rsr or wants to
know about rowing, from the base of the pyramid all the way to its very
peak.

Warmest regards,

Kit Davies

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Jul 6, 2015, 11:28:02 AM7/6/15

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On 06/07/2015 00:49, Carol Dailey wrote:

> Okay, and I'm going to call most of these responses a complete load of hooey. For people that pride yourselves on all things scientific and eschewing the regurgitated claptrap that passes for good advice, REALLY? Oh, little girl, just don't row so hard! Forget gearing, forget inboard and outboard, don't worry your little head with numbers. Just enjoy your sculling.

This is unbelievable!

You got exactly what you asked for, and much more. Not only viable
numbers, but a proper description of the dynamics of the stroke.

I really suggest you reread the response above, this time with an open mind.

Kit

martin...@gmail.com

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Jul 6, 2015, 11:33:05 AM7/6/15

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On Monday, July 6, 2015 at 2:25:26 AM UTC+1, Charles Carroll wrote:
> Cat -

>
> All I will add to what Carl has said is that I have known Carl for a number
> of years, own one of his magnificent shells, and consider him a good friend.
> In all this time I have never known Carl Douglas to be patronizing.
>
> Carl's advice to you is superb. What's more, it is consistent with what Carl

> has been saying to people for years -- and by "people" I mean rowers and

> scullers and coaches and anyone else who reads and posts on rsr or wants to
> know about rowing, from the base of the pyramid all the way to its very
> peak.
>
> Warmest regards,
>
> Charles
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus

To stick my oar in (pun intended)

I've been asked to do some coaching of a couple of doubles. None of the scullers are 6 foot and probably all are around the 5'5" to be honest.

First impression is that they look like they row "short" in so far as their arc of the spoon isn't very long. Your standard rigging books tend not to look at athlete's height in relation to oar length but there is some ho
int of that on the oarsport site (Terry ONeill has influence ther I think but can't say for definite.) This makes sense but it soesn't really change your arc.

as a person you are fixed in where youcan reach so to some effect your arc (hand movement is a fixed length) (kleshnev gives you a formula) from that you can work out how much inbard you require to get to the magical 110 degrees.

Then, you could work out your span from how much overlap you want and then work out the outboard and thus overall length using your gearing ratio of 2.12 or whatever....

Having said this it is all theoretical and I don't think all of the calcs on where forces are applied and lengthsd etc are always clear. I may try some of these things but at the end of the day you need to be comfortable. if not then no matter what the theory says you will not be rowing as well and probably go slower..

martin

John Greenly

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Jul 6, 2015, 1:32:37 PM7/6/15

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Well, I guess I'll take a chance and contribute here. Cat, I hope you are still with us, and if so, please know that I'm absolutely certain that all the replies to your inquiry have been meant in good spirit, and did not come from any patronizing or belittling thoughts. That having been said, it takes only a moment's reflection to realize that the active posters on RSR are a bunch of guys who are used to just trying to get across information. Carl, for instance, has used those same words (he is an amazingly patient teacher) many times before. So I guess you may have to cut us some slack on wording.

Maybe I can help a little with your concerns above. Your first sentence I'm guessing was the inspiration for Carl's reply; let me see if I can amplify a bit. First of all, the difference between 288/88 and 285/85 is really not very big- the gearing is the ratio of outboard to inboard length, and the outboard (200) is the same, while the inboard is either 88 or 85. That's only a 3.5% difference in gearing, which is indeed quite small compared with even mild differences in conditions- a couple of mph wind on head vs tail will make more difference than that.

It's kind of amazing that we ordinary mortals generally use gearing that differs only in the third significant figure from that used by the 6'6, 220 pound giants of the Olympics.

So why did you feel so much heavier a load in Florida? I don't know, but for now let's ignore possible differences in conditions, or just that you were rowing harder than usual under those circumstances. The major effect of the shorter inboard is that you will reach a larger angular arc with your stroke. Look at it this way: you have some particular length of motion on the slide, some particular body swing and arms of a particular length, all of which add up to some particular distance that your hands can travel from catch to finish. That's your reach. That distance traveled by the handles moves the oars through their arc. If you remember the geometry formula for the length of a circular arc, S = R*theta, then for us, S is your reach, R is the inboard length, and theta is the total angle swept out. You can see that for your particular S, the shorter R is the bigger theta is.

Now, with a fixed outboard length this means that at a given boat speed, with shorter inboard your drive will last a longer time. It takes longer for the blades to travel through that longer arc in the water. That means that to go at that boat speed you can actually pull less hard than the change in gearing would suggest, because your blades are in the water for a longer distance and time.

But then it can be that when you shorten the inboard you will feel the change in rhythm: your drive is taking longer at the same speed. If you then naturally try to speed the drive time up to what you're used to, you will be working harder (and going faster), and of course therefore get tired quicker.

So the real question is, with which rigging can you actually sustain a given boat speed the easiest; or, equivalently, which rig lets you sustain a higher speed to win races! It's a tradeoff between force and time- should you pull harder for a shorter time, or pull less hard for a longer time, at a given boat speed? Generally a longer arc is more efficient (up to some limit that most of us mortals can't reach anyway). But it may take quite a few miles to get used to it to use it optimally, hence the advice to get comfortable with a rig, and then to explore its outer limits. My own feeling is that many of us would do better with a shorter inboard- again, the Olympic giants use 88 or so... doesn't that indicate that a 5'11 old guy with limited knee range like me would do best with a shorter inboard? Yes! And if your shoulders are not as broad as Mahe's (mine sure aren't) then your reach will be better with a span of less than 160. I don't know how you would deal with team boats, but for yourself smaller dimensions would almost certainly be better.

Cheers,
John

Jim Dwyer

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Jul 6, 2015, 10:14:54 PM7/6/15

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Carol:

I have rowed for almost 50 years and this is what I have found.

While it is true that the load is determined by how hard you pull if your
gearing is too heavy it will take too long to complete a stroke full and
your rate will be very low.

You are 52 and very small.

I would recommend that your gearing should be as light as possible.

Start with 160 span and adjust the oars as short as they can go. Try for
even less than 285 by screwing the handles in all the way. Your inboard
should be at least 88. I use 88.5 and add CLAMS in a headwind. Try this
and row at racing pace and see what your rate is.

If they are your oars to modify I would take them to the CII booth at a
major regatta and have them cut the oars down. They can cut off a couple of
cm and glue a new plug in so that the handles can be adjusted all the way
down to the taper on the shaft.

I hope that this helps.

Jim

"Carol Dailey" wrote in message
news:affca842-9efa-4bb5...@googlegroups.com...

James HS

> I stand by what I first said -- namely, that Carl's reply is brilliant.

>
> The Japanese have an aphorism. "Read a book a hundred times and you will
> understand it." I certainly think this would be excellent advice about Carl's
> post.
>
> Warmest regards,
>
> Charles
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus

Whoa, now, Charles, take it easy! Of course you apply the load. What is not immediately obvious is which of the numerous possible factors might make you feel that you need to apply more (or less) load: conditions (wind and water), the competitive spirit, an uncomfortable rig, just having an off day...? All the ramifications of those factors add up to more than a "novice question", it seems to me. All the replies here, coming from various points of view, show how many sides there are to the rig questions.

And, yes, the word "load" is being used in a way that is not up to your standard of precision. But let's cut some slack here too, please. You must admit that simply pointing out that you apply the load does not fully address Cat's question. She has a rig that feels uncomfortable to her, and I'm sure you could find a quote from one of the gods of coaching that would agree that being comfortable in the boat is important.

Speaking of quotes, surely you will agree that Fairbairn is using language in a much more poetic than scientific way in that sentence. NO effort?? Elastic draw?? I think I know what he means because I know the feel of it, not because those particular words pin it down in some exact and definitive way. If you didn't already know the feel of it, maybe those words would help, and maybe not.

Words are imprecise tools at best (at least I struggle with them all the time). Clear though Carl's post might be to you (and, I think, to me), it is quite possible that to someone else, and through no fault of theirs, the words might convey something different. We all read intent as much from a speaker's face as from his or her words, and that makes these written conversations challenging. I hope Cat has not given up on us. I'm finding this discussion very interesting.

cheers,
John

martin...@gmail.com

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Jul 8, 2015, 4:54:11 AM7/8/15

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Pseudo-Science (The Wrath of Carl)

As I said in earlier post I’ve been looking at a similar issue so trying to refresh my memory on rigging have been trawling around looking for information which may or may not be useful and I present some thoughts here for your comment etc.

First my disclaimer is that there is a lot more ignored below than looked at as no fluid mechanics/dynamics have been klooked at – human shapes are all different, no person/boat/rig.river/weather combination will ever produce two identical strokes. This is just a methodology to get a starting point.
Second point is gearing – talk to or read different coaches and they will meaure this in a variety of ways. Some a simple ratio between inboard and outboard of the oar – others take into account the width of the swivel, others that the forces are not applied to the ends of the oar but at some point closer to the pin (from both ends) My feeling is that this ratio is useful as long as you always measure it consistently. It may also help if you have a crew boat of varying heights and wish to rig each individual then keeping this ratio consistent across all athletes may help.

We move the boat past the spoon of the oar. So in theory the further the spoon is away from the pivot point the further the boat will travel for each stroke. For whatever reason, it appears to be a consistent thought that the arc of the stroke should be around 110 degrees. (1.92 rads).

The arc length of the athlete is governed by their height, leg length, arm length flexibility and all other such good stuff but Kleshnev has given a formula to calculate this as

0.297865 * height + 108.387 (cm)

This is based on anthrpometric data and is probablty an ideal – I did see one reply from him where he would adjust some of his calculations due to age (e.g. master could be 95% of the ideal)
Using 157.5 (approx. 5’ 2”) this would need a radius of 157.5/1.92 (82cm) to achieve the 110 angle. What I have found is that this is not the inboard. From rowing illustrated (?) kleshnev gave a further explanation

“The length of the arc is calculated at the middle of the handle, so half of the handle width is subtracted from inboard length (6cm from the top in sculling and 15 cm in rowing).
Also, the oar rotates around pin, not around the surface of the gate, so half of the gate width = 2cm is added.
In your case, actual inboard = 87 – 6 + 2 = 83cm, which give us 159.3485 cm arc length at 110 deg angle”

So by reversing this the inbard we are looking for is 86 cm
The next step for me is to calculate span based on the desired overlap of between 15-20cm (again some figure commonly used – no idea why). Geometrically, a greater overlap (smaller span) will require the athlete to sit further towards the bow of the boat to achieve a constant position oif the hands in relation to the body at the finish. If we said an overlap of 18 then span would be (86*2)-18 = 154.
This leave the outboard to be added on and this is where the “gearing” ratio may help. This is probably best found by trial and test but at 2006 World Chmps FISA used (Outboard-2)/(span/2) the range was 2.441 – 2.484. As a atarting point lnowing athlete is not a female Olympian maybe put the ratio at 2.4 so we get (2.4*77)+2 which is approx. 187.

So my suggestion to start with would be a span of 154, sculls 273 long with 86cm inboard.

Then start to test it by seeing how fast you go and if adjusting it in any direction makes you go quicker .

James HS

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Jul 8, 2015, 5:14:12 AM7/8/15

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Love the calculation - but a quick google shows that in general the smallest spread on a single is 156? - so maybe the overlap should be 200mm

However - and this is no guarantee as I like the scientific approach - I have never seen anyone scull with 156.

Over the summer I will mess around with some of these as I like the approach!

James

James HS

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Jul 8, 2015, 5:22:07 AM7/8/15

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As a post script - there is an interesting chart at
http://www.biorow.com/rigchart.aspx

Produces numbers that are quite different to what I expected!

James

martin...@gmail.com

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Jul 8, 2015, 6:24:25 AM7/8/15

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Hi james,

I've seen the bio row spreadsheet and some of Valery's other bits and bobs as part of his rowing bulletins.

I Just looked at it geometrically and now need to see what I can do in the real world without new riggers or sculls :)

There is also this for some further reading

http://www.slideshare.net/rcaroe/rowinangle-changes-duetospanandinboardjan13?related=1

There is an associated spreadsheet but cannot acces that as the link is broken. Have mailed them to ask for it.

there is also this on the oarsport website whicjh sort of corroborates some of my calcs as the spans are similar and therefore if you keep overlap similar you will get the angle but the arc length of the spoon will increase as the athlete gets shorter (I think - need to do some spreadsheet work on this !!!!)

1x 2x 4x
Height of Sculler Span Scull Length Span Scull Length Span Scull Length
185 - 195 158-160 287.5-290 157-159 288.5-291 156.5-159 289.5-292
176 - 185 156-158 285-287.5 155-157 286-288.5 154.5-156.5 287-289.5
166 - 175 154-156 282.5-285 153-155 283.5-286 152.5-154.5 284.5-287
155 - 165 152-154 280-282.5 151-153 281-283.5 150.5-152.5 282-284.5

if the pan has to go out but your inboard stays the same I think the arc length and angle will stay the same but overlap would reduce and to keep the same distance between the scull handles at the finish you wopuld move closer to the stern which will increase the catch angle and reduce the finish angle.

I've 2 sets of riggers for my old wooden scull so if I can find speed coach stuff I will see if I can get some figures on changes to speed. (may take some time as have a newborn son slowing rowing activitis down.) I need a guinea pig lol

s...@ku.edu

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Jul 8, 2015, 8:00:58 AM7/8/15

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I think of this problem a little differently and adjust my oars in relation to the adjustments to my 1x. First I adjust my foot stretcher and tracks so that I can get between the center and the bow edge of the seat holes through the line of work. I test this by marking the spot with tape over the tracks, so I feel/hear a click when I reach my spot. (BTW when I have good chest up/chin up posture I'm better at hitting the spot.) At the same time I need to adjust the inboard so that I have adequate clearances for a good release--no point in getting a good catch angle if you get stuck at the finish. Then I adjust the outboard so that I can sustain my race pace over 5k at stroke rate 28-30, which over the years has been my most effective rate, and have a little left over for a final sprint. Then I tinker and play on the margins as the spirit moves me, but mostly I leave my settings the same and just try to row well. My settings are nothing radical: spread = 58.6; Croker S39 185/86.

Steven M-M

carl

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Steve S

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Jul 8, 2015, 5:33:50 PM7/8/15

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Cat's original post was, in short, given the purchase of Smoothie 2 plain edge, 285-290 cm adjustable length oars, how should I rig?
The ensuing excellent discussion has focussed on spread/overlap/outboard in a very general way, with lots of attention paid to how these relate to the angle that could potentially be swept out by the sculler.
Yet it has subtly ignored an element that is crucial to the discussion of optimal sculling set-up for masters rowers, especially for short middle-aged and senior men and women-- for example, for the 173-cm tall 72-year-old author of this post.
That topic is blade size, and how it interacts with spread/overlap/outboard. Blade areas for elite national-team scullers are on the upswing:
- Xeno Müller won gold and set an Olympic record that lasted 16 years rowing with 780 sq cm C2 Big Blades.
- The blade area of a Smoothie 2 plain edge is 822 sq cm
- The blade area of C2 Fat 2s is 857 sq cm
In most settings, the blade sizes used by elite athletes are adopted by (or foisted on) masters scullers and early-teen scullers. I am convinced these much less powerful folks are overloaded -- they are rowing with too much blade area, too much outboard, and too little spread relative to the power they can maintain for the duration of their events. Visible at any masters regatta, the consequences for overloaded scullers (and similarly for overloaded rowers) are sometimes comically short immersed arcs, especially at the high ratings fashionable in masters racing, and an appalling failure to accelerate through the stroke.
My club has taken this to heart and the standard among the top masters scullers, who have medaled in all their races in 2015, is 775 sq cm blades, except for Ellen Braithwaite, who races at 745.

carl

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Jul 8, 2015, 6:56:52 PM7/8/15

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Every blade since Macons has sought greater wetted area.

If your stroke is all & only about drag - the stalled plate case - then
there might be some logic in having the largest blade area that doesn't
itself impede its use. But the stroke is not like that. Over large
parts of the arc there's substantial flow along the blade - from tip to
root & later from root to tip.

Hydrodynamic lift requires a longitudinal flow, but that flow also
generates fluid friction. A well-designed foil has a sensitive balance
between wing loading, skin friction & the relationship between lift &
drag, & in general you want a foil with a high aspect ratio which,
translated into an oar-blade, means it's wide (top to bottom, across the
flow) but short (tip to root, with the flow). That's hardly an accurate
description of a rowing or sculling oar-blade.

Further, the greater the area beyond that required for efficient
function as a foil, the greater the unnecessary losses to fluid
friction. Oarblades already have extremely low wing loadings in the
lift-generating phases of the stroke so it's not smart, for marginal
efficiency gains in mid-stroke, to increase the blade area & thus boost
frictional losses in the first & last parts of the stroke.

That's more particularly so for the smaller, less strong person. It
makes no sense to give a veteran woman sculler a blade that's within a
few % of the same area as used by a male world champion - the real
additional frictional losses at the ends of the stroke can't possibly be
compensated for by any notional reduction in mid-stroke losses.

You can see this with wind turbine blades. The layman's view would have
not just 2 or 3 very slim blades but would assume that more & broader
blades must interact with more air & thus better extract energy from the
wind flow. The reality is that the fluid frictional losses from a
greater total blade area would more than destroy any possible gains.

Henry Law

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Jul 9, 2015, 9:15:47 AM7/9/15

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On 08/07/15 15:14, martin...@gmail.com wrote:
> The one thing I do know is that I know nothing like enough.

The most interesting, knowledgeable and skillful people I know are the
ones who often say something like that.

<flameproofsuit>Would that people in other walks of life would admit the
same, such as TV commentators, MPs ...</flameproofsuit>

--

Henry Law Manchester, England

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Jul 9, 2015, 2:46:51 PM7/9/15

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John Greenly

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Jul 9, 2015, 7:18:20 PM7/9/15

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On Thursday, July 9, 2015 at 3:52:10 PM UTC-4, Kit Davies wrote:
>> Boy, do I wish some software-savvy person could come up with a common sketch-board- maybe at a different site?- that we could all use. Drawing would make so many things so much easier to discuss!!
> > John
> >
> I knew I'd find myself useful in this thread at some point.
>
> http://stable.ascii-flow.appspot.com/#Draw
>
> 1. Draw your butchered blades
> 2. Click 'Export'
> 3. Copy&paste the result into your post.
>
> Kit

Oh yes, thanks Kit, I remember this now!! My dream, though, would be something that we could literally draw on, rather than cobbling something up out of ascii characters. Could do it using any old drawing software, export a jpeg and post it on one of the photo sites, I guess. But is there some way for multiple people to all draw on the same screen at the same time? that would be a lot of fun.

John

Charles Carroll

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Jul 9, 2015, 7:29:43 PM7/9/15

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> longer outboard means more efficient coupling
> of power through the blades.

Hi John,

Wouldn’t longer outboard mean faster blade entry? Because the longer the
outboard, the less you have to lift the oar handles to reach the desired
depth.

And wouldn’t faster blade entry mean increased effective stroke length?

This is off the top of my head. I’ve got to run. We are taking the children
to dinner and I can’t be late. It is a goodbye dinner for a young man that
has been with us since 21 August 2002.

Cordially,

Charles

John Greenly

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Jul 9, 2015, 7:45:26 PM7/9/15

to

On Thursday, July 9, 2015 at 7:29:43 PM UTC-4, Charles Carroll wrote:
> > longer outboard means more efficient coupling
> > of power through the blades.
>
> Hi John,
>
> Wouldn't longer outboard mean faster blade entry? Because the longer the
> outboard, the less you have to lift the oar handles to reach the desired
> depth.
>
> And wouldn't faster blade entry mean increased effective stroke length?
>
> This is off the top of my head. I've got to run. We are taking the children
> to dinner and I can't be late. It is a goodbye dinner for a young man that
> has been with us since 21 August 2002.
>
> Cordially,
>
> Charles

Hi Charles, I hope you have- had- a wonderful dinner!

yup, all else being equal, which it never is, you're right, you might gain a bit of useful length at the catch. Remember though that longer outboard means more inertia of the oar, so you'd have put more effort into raising the hands, proportional to the increase of speed you attain at the outboard end. If you did get a larger effective catch angle (I was assuming constant), then that would lengthen the drive even more and amplify the time/power relationship I described. But the amounts of length change we are dealing with here are pretty small and I doubt this effect would be noticeable.

...and I was of course assuming that your catch is in any case already flawless!

--John

Jim Dwyer

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Jul 9, 2015, 7:58:19 PM7/9/15

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Charles:

Your story below does not make sense.

If you were using a SpeedCoach with an impeller ("years ago" as you have
stated) then your split would be the same rowing upstream or downstream. If
you had a GPS unit then the splits would be different.
Your drives should feel the same rowing in either direction assuming that
you are pulling with the same force in both directions. Also: You are
rowing the same speed relative to the water that you are floating in
upstream or downstream and the load or gearing would feel the same to you
while you are rowing. Of course it would take you longer to get back
upstream to your starting point.

Jim

John Greenly

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Jul 9, 2015, 9:47:12 PM7/9/15

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Good point! In his description, he wasn't pulling the same in both directions: much harder upstream. Let's see if we can come up with a scenario. If the ferocious current was 3.5 m/s, then he only needed to row at 2.5 m/s to see 6 on his GPS-- just gliding along. But then in the other direction he had to row 4 m/s to make good 0.5-- warm work indeed! Well, Charles??

John

Kit Davies

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Jul 10, 2015, 4:41:04 AM7/10/15

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Yes, that would be ideal. Twiddla allows online collaborative drawing
and is the best free one I know but you have to be using a latest
browser. Eg, to get you going:

http://www.twiddla.com/2208909

You can add to the drawing as you wish

Kit

martin...@gmail.com

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Jul 10, 2015, 4:42:36 AM7/10/15

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Carl,

If I am following you correctly and forgive me if I am not you seem to be describing a macon spoon attached to a shaft at an angle such that the centre line of the soon is parallel ish to the water.

This reminds me of those power blades that were around at one time. I remember the small model on display and some of the papers that showed that theoretically they were good but in practice I found them horrible to row with. perhaps it wasn't the design but the build quality if they twisted and gave the horrible feel you mention.

whicj also reminds me of aluminium shafted blades. superior stiffness to allegedly increase power efficiency but had some sort of resonance that made them "pop" out of the stroke on a regular basis *every 10-15 strokes if I remember correctly

sander

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Jul 10, 2015, 12:09:29 PM7/10/15

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One has to consider the magnitude of the changes one can make with the sculls owned. For example, if I were to increase outboard by 3cm by from from 287cm to 290cm on C2 sculls but adjusting the collar to keep the inboard (and everything else the same), a quick estimate gives that at 32spm, constant 1:50/500m pace you Drive Time / Stroke Time ratio goes from 47% to 48%, and the overall efficiency goes up by 0.25%. This being a crude estimate, let's say it is somewhere around 1% at best. Do we expect a sculler can "feel" this? I don't think so. Speed gain for a typical Masters rower over 1km might be between 0.5 and 2 seconds. Big enough to be interesting, but small enough to be negligible compared to other factors impacting speed.

nosmo

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Jul 10, 2015, 12:55:02 PM7/10/15

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On Wednesday, July 8, 2015 at 8:13:13 AM UTC-4, carl wrote:
> Much of fluid dynamics is theoretically calculable from 1st principles,
> starting from the Navier-Stokes equations,

Except it is much worse than that. The Navier-Stokes equations is not derivable from 1st principles. You can't start with a Hamiltonian or any thing else and derive the Navier-Stokes equation. Back in grad school (20 odd years ago) I attended a lecture by a Japanesse physicist in which he proposed some corrections to the N-S equatation. None of that would apply to the flow regimes relevant to boats though. If you approach fluid dynamics from an empirical engineers point of view it is amazing what people have figured out. But if you start from a first principles physics perspective you get almost no where. If one encounters a flow regime one has no experience with all prevous knowledge and intuition can go out the window.

Back to the original post:
Just want to emphasis a few things others have said.
The amount of overlap is mostly determined by the span and the inboard. I don't see how Cat's hands can not be close to on top of each other with a 160/87 settings. I think she needs someone very experienced to check things and look closely at her.
I'd recommend starting with the shortest oars and setting the inboard to be as comfortable as she can it. Possibly cutting the blades down (off the inside edge) if the load feels to heavy. Croker has (or had) some info on thier web site on how to do this for their blades, but basically you want to follow the same general curve.

Re blade shape...
Earlier this year I did some experiments with one Dreher Apex blade (187/87) and one C2 Macon (192/87). Rowed with eyes closed both under power and on starts. Changed which side had the Macon which had the Apex. Repeated it. I went straight every time. The did feel a bit difference but I could not tell if I turned one way. Nor could I detect a wobble in the movement of the stern from side to side during the stroke. Did some six 500m peices swapping the blades between pieces. Results were inconclusive. Variation in speed between peices with the same oars was greater than the variation between oars. Next week did 4x 8 minutes changing blades between each one. Again inconclusive results--every piece was within 15 meters of eachother dispite turns and steering around other boats that did them with me. Will get back to doing more controlled experiements at some point. I regularly swith between C2 macon, Dreher Apex, C2 smoothie 1's and C2 smoothie 2. The feel is a bit different, but it is very hard to say if there is a difference in speed.

carl

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Jul 10, 2015, 1:25:37 PM7/10/15

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On 10/07/2015 17:09, sander wrote:
> One has to consider the magnitude of the changes one can make with the sculls owned. For example, if I were to increase outboard by 3cm by from from 287cm to 290cm on C2 sculls but adjusting the collar to keep the inboard (and everything else the same), a quick estimate gives that at 32spm, constant 1:50/500m pace you Drive Time / Stroke Time ratio goes from 47% to 48%, and the overall efficiency goes up by 0.25%. This being a crude estimate, let's say it is somewhere around 1% at best. Do we expect a sculler can "feel" this? I don't think so. Speed gain for a typical Masters rower over 1km might be between 0.5 and 2 seconds. Big enough to be interesting, but small enough to be negligible compared to other factors impacting speed.
>

At all times in sport we should be seeking to aggregate a wide range of
quite marginal gains to form the bigger, better picture. AFAIK there
are no "killer apps" in rowing, but there are many small (or smallish)
performance gains to be made.

I may have misunderstood you, but I would respectfully suggest that any
sculler who felt they could safely disregard anything offering a
potential 0.5 to 2.0 second (1/4 to 1 length) gain was not serious about
going faster.

In improving performance I'd suggest that we shouldn't try to select
just one major enhancement but to integrate every conceivable benefit
into a compatible whole. By all means do the easy things first, but
remember that there's a lot more to it. Being good at playing scales
can improve your playing skills but doesn't of itself make you into a
good musician - that takes years of careful attention to detail (& some
natural talent). Good rowing is no different.

carl

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Jul 10, 2015, 1:51:56 PM7/10/15

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On 10/07/2015 17:55, nosmo wrote:
> On Wednesday, July 8, 2015 at 8:13:13 AM UTC-4, carl wrote:
>> Much of fluid dynamics is theoretically calculable from 1st principles,
>> starting from the Navier-Stokes equations,
>
> Except it is much worse than that. The Navier-Stokes equations is not derivable from 1st principles. You can't start with a Hamiltonian or any thing else and derive the Navier-Stokes equation. Back in grad school (20 odd years ago) I attended a lecture by a Japanesse physicist in which he proposed some corrections to the N-S equatation. None of that would apply to the flow regimes relevant to boats though. If you approach fluid dynamics from an empirical engineers point of view it is amazing what people have figured out. But if you start from a first principles physics perspective you get almost no where. If one encounters a flow regime one has no experience with all prevous knowledge and intuition can go out the window.
>

You are right on the limitations of mathematical analysis, although
possibly a little harsh. And right to say that empiricism has taken us
a huge way in our understanding of F-D. While computational fluid
dynamics is a powerful tool-kit and highly useful for predictive work,
its predictions do usually need to be validated by practical experiment
& measurement.

I do recall a physicist confidently telling me that it was impossible to
predict hull drag as the flow processes are necessarily chaotic. He was
surprised when I told him that empirically derived relationships gave
good-to-excellent results in most cases & that CFD was coming along
nicely. That said, even now there is argument, e.g., over how best to
predict complex flows around aircraft wing roots but, happily or sadly,
we don't yet have to deal with transonic flows in rowing

> Back to the original post:
> Just want to emphasis a few things others have said.
> The amount of overlap is mostly determined by the span and the inboard. I don't see how Cat's hands can not be close to on top of each other with a 160/87 settings. I think she needs someone very experienced to check things and look closely at her.
> I'd recommend starting with the shortest oars and setting the inboard to be as comfortable as she can it. Possibly cutting the blades down (off the inside edge) if the load feels to heavy. Croker has (or had) some info on thier web site on how to do this for their blades, but basically you want to follow the same general curve.
>
> Re blade shape...
> Earlier this year I did some experiments with one Dreher Apex blade (187/87) and one C2 Macon (192/87). Rowed with eyes closed both under power and on starts. Changed which side had the Macon which had the Apex. Repeated it. I went straight every time. The did feel a bit difference but I could not tell if I turned one way. Nor could I detect a wobble in the movement of the stern from side to side during the stroke. Did some six 500m peices swapping the blades between pieces. Results were inconclusive. Variation in speed between peices with the same oars was greater than the variation between oars. Next week did 4x 8 minutes changing blades between each one. Again inconclusive results--every piece was within 15 meters of eachother dispite turns and steering around other boats that did them with me. Will get back to doing more controlled experiements at some point. I regularly swith between C2 macon, Dreher Apex, C2 smoothie 1's and C2 smoothie 2. The feel is a bit different
, but it is very hard to say if there is a difference in speed.
>

That's great, someone else who likes to experiment! I still remember
when we were being told with great seriousness that a new blade shape
would give us as much as 7 seconds per 2k, even though no such gains
were ever seen in race statistics. But everyone still felt they had to
adopt the new blades.

Charles Carroll

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Jul 10, 2015, 2:10:58 PM7/10/15

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Hi Sander

“Do we expect a sculler to feel this” — the rigging changes he or she is
experimenting with?

It seems to me that this is an excellent question. Over the years there have
been many discussions on RSR about rigging and gearing. Some of us are very
passionate about these discussions and argue vigorously for our favorite
opinions on the subject. And to support these opinions we offer all sorts of
numbers. It all seems very reasonable.

Now my memory may be failing me, but I cannot recall any reports of field
tests on gearing and rigging.

So here is a brief field report of my experiences.

I spent several years playing with gearing ratios, decreasing and increasing
the span, moving the footstretcher, and everything else I could think of. On
my Carl Douglas 1x I could decrease or increase the span from 156 to 162 cm.
I could move the footstretcher far enough sternwards to completely
obliterate my finish, or so far enough bowards that I virtually lost all
effective catch angle. I increased my inboard to 89.5 cm and decreased it to
83 cm. I tried everything I could think of with one exception. I didn’t much
play with was the height of the gates. I kept them at 1 or 2 snappers
because I pulling higher produced an unpleasant sensation in my shoulders.

So after field testing many different configurations, here is what I
concluded:

I can only reaffirm what Valery Kleshnev wrote in the September 2011 Rowing
Biomechanics Newsletter: “Changing oar length in quite large scale doesn’t
affect significantly forces, power and boat speed …”

It is fun to play with rigging. It is even more fun to understand the ideas
of rigging — the relationship of inboard to outboard, blade shape, stretcher
placement, oarlock height, etc. But in the end isn’t it only prudent to keep
things in perspective? The truth is that the stakes are just not very high —
leastwise, this is true in my case. I would conclude that it is more
important to enjoy your rigging than it is to produce theoretically ideal
rigging numbers. Rig a shell so that you feel comfortable sculling it. Stop
fretting about whether the rigging is ideal.

Cordially,

Charles

Charles Carroll

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Jul 10, 2015, 2:28:11 PM7/10/15

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But isn’t there is one thing about rigging that should really concern anyone
who wants to pull on an oar handle to go faster — and that is the effect of
oar angle on gearing?

Valery Kleshnev writes:

“Did you know that the effect of the oar angle on gearing is significant at
angles greater than 45deg?

• An angle of 60deg makes it twice as heavier;
• An angle of 70deg makes it three times as heavier;
• An angle of 80deg makes it six times as heavier (RBN Volume 7 No 72, March
2007)”

And this brings me to what I quoted from Walter Martindale earlier in this
thread.

“… get the 70 degree catch angle. The blade does a lot of interesting things
in the water at that angle.”

The only thing I add to what Walter says is that these ‘interesting things”
only happen if you are going fast enough:

“The hydro-lift effect doesn’t work at low boat speeds (RBN 2007/12), so
pushing the blade outwards at the catch increases its slippage through the
water and amount of energy wasted.”

But I will leave it to John and Carl and others, who possess real expertise,
to discuss “interesting things.”

sander

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Jul 10, 2015, 2:33:56 PM7/10/15

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Don't think we disagree. Just wanted to point out that what scullers 'feel' may be very subjective and not due to a real difference in load. I explicitly include myself here. Despite being able to calculate what I did, I row with short sculls. Why? I don't know. I am tempted to change them tomorrow, just to test.

Charles Carroll

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Jul 10, 2015, 2:39:25 PM7/10/15

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> If you were using a SpeedCoach with an impeller
> ("years ago" as you have stated)

Hi Jim,

Years ago I think I wrote that NK’s StrokeCoach GPS can be used with an
impeller. But I don’t have an impeller. So all my numbers are purely GPS.

I should have been clearer about this. I apologize for the misunderstanding.

Warmest regards,

Charles

Charles Carroll

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Jul 10, 2015, 3:20:05 PM7/10/15

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> At a 70 degree catch angle the blade

> does a lot of interesting things

I’m sorry. I should have been clearer. At a 70 degree catch angle what
interesting things does a blade do that it doesn’t do at say a 60 degree
catch angle?

John Greenly

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Jul 10, 2015, 5:02:11 PM7/10/15

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Kit, yes!!! I just looked at this, it's good! we can definitely use this, thanks very much.

--John

pble...@gmail.com

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Jul 10, 2015, 10:18:31 PM7/10/15

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On Friday, July 10, 2015 at 1:51:56 PM UTC-4, carl wrote:
> You are right on the limitations of mathematical analysis, although
> possibly a little harsh. And right to say that empiricism has taken us
> a huge way in our understanding of F-D. While computational fluid
> dynamics is a powerful tool-kit and highly useful for predictive work,
> its predictions do usually need to be validated by practical experiment
> & measurement.
>
> I do recall a physicist confidently telling me that it was impossible to
> predict hull drag as the flow processes are necessarily chaotic. He was
> surprised when I told him that empirically derived relationships gave
> good-to-excellent results in most cases & that CFD was coming along
> nicely. That said, even now there is argument, e.g., over how best to
> predict complex flows around aircraft wing roots but, happily or sadly,
> we don't yet have to deal with transonic flows in rowing

I'm not saying computational fluid dynamics doesn't work or that there is not a very good understanding of fluid behavior in many many circumstances, or even that the theory is not very very good. Just saying that the therory is not derived from first principles. What engineers have done over the years is truely amazing. But as of when I left the field, if you ask a physicist about some very basic things about energy dissipation in turbulence and you don't get any better then Kolmogorov's 1945 paper which was really nothing but dimensional analysis. I did my thesis on flow between concentric rotating cylinders. Hard to get a simpler geometry. There were at least a half dozen papers on the drag as the Reynolds number got very high and they were all wrong. Once the experiment was done, it could be explained, but no one knew the answer and computers will not be powerful enough to get to very high Reynolds number. As an aside a fellow grad student once said to me "Talking to you turbulence guys is depressing because it is obvious that none of you believe a damn bit of the theory."--no reason we should have because the theories weren't really proven.

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Jul 12, 2015, 4:55:18 PM7/12/15

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Walter:

Thank you so much for this! And Steven and James HS and John Greenly (what a true gentleman!) and everyone for a wonderful discussion. This is exactly what I am looking for and even more than I expected from rsr. Even though I've not commented, I've read all of these posts a few times over. Walter, the video you mentioned below is the perfect illustration of the points you made. (As an aside, I wonder if the Germans geared higher because they thought they'd get more of an assist from the tailwind? It does seem sort of a "novice mistake" and the very one I was trying to avoid. And is the early opening of the trunk symptomatic of too high a gearing?) The 85 inboard at Florida was just as you said...it made the boat feel so very heavy. It was the effect on the drive of the different gearing question that I originally asked that I wasn't able to puzzle out for myself and you answered it for me. I even tried to draw it out for myself with paper and pencil, but couldn't quite figure out the geometry/math of the angles.

Friday evening, I went with 87/286. I've rowed about 30 miles in the ensuing 36 hours with them set that way. I know 16 of those miles were at a span of 160. Not sure of the rest. Hand overlap nirvana compared to the 88's. No discernible difference in gearing, just a whole lot more comfortable, and really felt more symmetrical. The 160 spread is the Peinert x25 single. I'm going to try to get my hands on my club's LW Swift from here on, but the span is 159. I'm hoping the .5cm off either side doesn't make my overlap feel all that different. I will also try your suggestion of 285 overall length and see how that feels.

And to John, you commented earlier about my oarlock height. I've consistently kept the Peinert rigged as high as she will allow. I'm long arm and torso. For the person who wrote the excellent post on blade size, I totally agree. Smoothie two plains are the smallest blade size I'm likely to find for sale used here. That's why I grabbed this set. All the ones at my club are even bigger! Someday maybe I'll work up the nerve to take a saw blade to them.

I'm thinking out loud about another question that puzzles me as it relates to inboard length, forearm length and working through the pin. Please understand that I'm not even sure if I'm asking the right question or even a valid question, but I can't reconcile it in my brain.

Assume an inboard of 88; set foot stretcher to appropriate position for finish. So my hands are X distance from the pin at the finish. Now change inboard to 87. To get the same appropriate hand position at finish, feet can move slightly to stern, putting Cat further up through the pins, correct? Does this have any effect on forearm/elbow angles? I'm wondering why 87 feels so much vastly more comfortable than 88, and why it seems both easier to extract the blade and keep my elbows up?

These things do matter to me, even if just for my own personal edification. I am a total immersion learner. (Yes, I've read 400 pages of Davenport on rigging). I'm a novice sculler but an elite athlete in many types of small boats other than going backwards ones. That's why I asked for advice here. There are true geniuses of rowing that post here regularly and I'm grateful for the help.

Cat

Charles Carroll

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Jul 12, 2015, 5:00:25 PM7/12/15

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> Imagine driving a standard transmission car,
> getting from first gear to fourth without all the
> intervening gears...

Walter,

You know you have a real gift for un-complicating the complicated.

I remember years ago when I asked about the feasibility of buying one of the
most beautiful shells I have ever seen — a rosewood double that Carl made
for a 90 kg crew. There were lots of good ideas on RSR about this, but none
that appealed to me so much as yours.

You reminded me that I scull a 70 kg shell, which Carl built for me and
which I have described as perfect. Then you said that in an oversized shell
I would “bob around like a cork on water.” Better, you continued, that if I
really wanted a double go out and find one suited to my size, or better yet,
ask Carl to make one for me.

I am always glad to see a post from you.

Charles

Charles Carroll

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Jul 12, 2015, 5:34:03 PM7/12/15

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> If you go to 86 inboard it will be less overlap

> and either will allow you to get a longer catch
> than an 88

Walter,

I love these discussions. I think they are great.

But you are talking about a mere 2 cm difference in inboard. Why can’t you
just slide your hands 2 cm down the oar handles if you want less inboard? Or
up 2 cm if you want more?

And how much is 2 cm actually going to add to the gearing? There is an
earlier post from John doing the arithmetic on this.

More than once I have had to use a big pipe wrench to free a nut frozen fast
to pipe fitting. The only way I loosened the nut was to find a long pipe
that would fit over the handle of the pipe wrench. And by “long” I mean
twice the length of the handle of the pipe wrench. Only a pipe of this
length could give me the leverage necessary to free the nut. The point is
that I just can’t see 2 cm making that much difference in gearing.

We have had these discussions about gearing on RSR since I started reading
the newsgroup. And they have always reminded me of the same thing — the
scene in the 1986 film, “Crocodile Dundee.”

I don’t know if you have seen the film, but here’s the script for that
scene.

_____
Teenage Mugger: [Dundee and Sue are approached by a youth stepping out from
the shadows, followed by some others] You got a light, buddy?

Michael J. "Crocodile" Dundee: Yeah, sure kid.
[reaches for lighter]

Teenage Mugger: [flicks open switchblade] And your wallet!

Sue Charlton: [guardedly] Mick, give him your wallet.

Michael J. "Crocodile" Dundee: [amused] What for?

Sue Charlton: [cautiously] He's got a knife.

Michael J. "Crocodile" Dundee: [chuckles] That's not a knife.
[he pulls out a large bowie knife]

Michael J. "Crocodile" Dundee: THAT's a knife.

[Dundee slashes the teen mugger's jacket and maintains eyeball to eyeball
stare]
Teenage Mugger: Shit!
_____

Of course inboard and knife play aren’t the same thing. But 2 cm certainly
wouldn’t have done it for old Dundee.

Cordially,

John Greenly

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unread,

Jul 13, 2015, 4:03:39 AM7/13/15

to

Wow, that is so cool! That guy is huge and his riggers are quite a bit higher than the ones on the boat I use.

I am going to talk to my club about flipping the clamps.

Brilliant suggestion :)

Cat

Henry Law

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Jul 13, 2015, 5:32:45 AM7/13/15

to

On 13/07/15 04:04, 2potsin...@gmail.com wrote:
> Spousta is a very good friend and club mate

Big b****r isn't he! Instant intimidation on the start line ...

Splat...@hotmail.com

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Jul 13, 2015, 7:02:13 AM7/13/15

to

Hello All,

I love reading your forum, I have learnt heaps, as I am still a relative newbie to sculling.

I too am looking for some advice re oar length and span. I am 184cm tall and 85kg and pull 6:30 for 2k on the erg. Currently my span is 160cm and oars (Croker S4) are 288/88. At this set up acheiving 32spm+ is hard work and not sustainable for 2k and I feel my catch angle needs to be increased. I also find my hands at the finish are really wide (think mahe Drysdale wide). My stretcher is placed so that when I drive the stern is maybe an inch at most above the water.

I am not sure if I am on the right track, but I am planning to change the span to 159 and I am thinking oars at 288/87. the other option I was given was oars 289/89 with a span of 159-160. My aim is to be able to race at 32 SPM without having to shorten the stroke or rush the slide.

Any advice you could offer would be greatly appreciated.

Cheers,

Anthony

John Greenly

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Jul 13, 2015, 10:18:49 AM7/13/15

to

Yes, I think Bob Spousta as a veteran sculler would be a fine role model for me. I have always lacked in the intimidation dimension. All I have to do is grow a couple of inches taller, put on about 60 lb of muscle and learn how to scull properly.

--John

John Greenly

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Jul 13, 2015, 10:32:17 AM7/13/15

to

Yes, I think Bob Spousta as a veteran sculler would be a fine role model for me. I have always lacked in the intimidation dimension. All I have to do is grow a couple of inches taller, put on about 60 lb of muscle and learn how to scull properly.

...I think I'll start tomorrow.

--John

Carol Dailey

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Jul 13, 2015, 5:07:59 PM7/13/15

to

Well, well, well....looky what just hit my Inbox :>>>

Karma?

GEARING RATIO

http://www.biorow.com/RBN_en_2015_files/2015RowBiomNews06.pdf

Cat

John Greenly

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Jul 13, 2015, 11:21:47 PM7/13/15

to

On Sunday, July 12, 2015 at 7:42:15 PM UTC-4, Charles Carroll wrote:
> > 2 cm shorter inboard gives you the equivalent of
> > more than 3 cm further reach to add to catch
> > and/or finish angle.
>
> Hi John,
>
> Sorry. I am neither thinking nor writing very well today.
>
> I thought I was addressing the issue of an 85 cm inboard. Shorter inboard
> equals longer reach but feels heavier. Longer inboard equals more leverage
> and feels lighter. Didn't Walter say that he didn't recall ever rigging an
> able-bodied sculler to an 85 inboard?
>
> Of course as you reduce inboard you'll feel and see more angle reached. And
> won't you also see more angle reached as you reduce the span? And again as
> you move the stretcher sternwards?
>
> But as you achieve more angle reached, doesn't the gearing become heavier?
>

> I thought this was the original complaint -- that the gearing was too heavy.
>

--Hi Charles, yes, I see what you're saying.

> Of course you can reduce this heavy feeling by moving the shell faster. I

> don't know the numbers -- Carl can probably give them to us -- but I seem to

> remember reading somewhere that lift doesn't occur until you have reached a
> speed at something greater 3 meters-per-second. At that speed you can use a
> greater catch angle without experiencing the feeling of heaviness that is
> associated with a slower speed. By the way, I think this is what Fairbairn
> was attempting to describe when he wrote, "Row the blade through with a
> springing hit, and elastic draw, without feeling any heaviness or effort."
>
> I have never read the above passage any other way than Fairbairn's
> describing moving a boat really well at a speed which allowed you to take
> the catch at a long reach. Unless I have completely misunderstood

> everything -- and this is a real possibility -- don't we today know that the

> absence of feeling any heaviness or effort in such a catch is due to lift?

I'm afraid not. Do we agree that that something feels "heavy" when it moves slowly in response to a pull or push, and "lighter" when it moves faster? Now, first of all, as someone has pointed out, you apply the load, and if lift is developed it is only in response to your load. But more to the point here, when the blade is lifting with best efficiency it will feel heavier, not lighter. When flow across the blade is producing lift, it will move slower (less "slip") in the direction perpendicular to its face (lower angle of attack, in foil lingo) with a given load. The oar rotation and the handle speed will be slower and so the handle will feel heavier in its resistance to moving under your load. Think of it in the limits: if the blades were not in the water at all (complete "slip", zero efficiency) it would feel wonderfully light and responsive, just what Fairbairn ordered, no heaviness or effort at all! On the other hand, if the blades were bearing against fixed posts (no slip, perfect efficiency, zero angle of attack) they would feel very heavy. The real situation in water is somewhere in between these extremes, thankfully closer to the posts than to the air stroke!

If you apply the same load to an efficient oar as to a less efficient one of the same length, you will be doing the same amount of work through the drive, (same force moving the handles the same distance) but the handles of the less efficient blade will be moving faster because that blade is "slipping" more against the water. So the drive will last a shorter time, and the gearing will feel lighter, but it's a fake-out: the boat is going slower despite the handles moving faster, and you'll get tired sooner if you try to go the same speed, because of the wasted power.

As to the heavy feeling at low speed, it's the same idea: when the boat is going slower, the handles are moving slower with whatever load you put on them. That feels heavy!! And of course when the boat is going faster, if you put on the same load you are actually producing more power (force x velocity) but it feels lighter because we feel the faster handle speed as an easier response to our load.

So, for instance, when you begin your racing start with that first partial drive it feels terribly heavy, and I think it would feel even heavier if you pulled equally hard with blades bearing against fixed posts (perfectly efficient) instead of stirring up the water (inefficient), again, because the handles would move slower. But, working against the posts the boat would take off quicker because all that load would go into moving the boat instead of the water.

Cheers,
John

wmart...@gmail.com

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Jul 15, 2015, 7:13:13 AM7/15/15

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Thanks John for your reply. The more I learn about rowing, the more I learn how much I don't know!

My boat is a six month old Filippi F1, with adjustable wing rigger, so I have plenty of scope for adjustment. It has been recommended to me today that I may need to move my rigger towards bow as my stern could be sitting too low.

The advice given was span 159, Oar length 287/88, moving the rigger on or two slots towards bow and leave the stretcher where is for now. This sounds like it might be heading in the right direction. So I might see how this goes and if not happy, will start at 285/87 and work from there. I definitely want to have my hands closer together at the finish as the wide finish doesn't feel like it is working for me.

I don't think it will take much to comfortably hit 32spm for 2k, as I have improved my strength and fitness as well as my technique since the end of last season. This season doesn't really start till October, so I still have plenty of time for further gains and adjustments.

Cheers,

Anthony