Fat2 vs smoothie

[Alistair Browne]

Although there is a danger of opening a can of worms...

The accepted wisdom seems to be that the C2 Fat2 spoon requires a much shorter overall length because it is so much more efficient.

My reaction to this, with no actual experience of using the Fat2 blades, is that it seems unlikely that any big blade is so inefficient that the Fat2 can make such a big difference.

Am I wrong?

Thanks,
Alistair

[robin_d...@hotmail.com]

Being a lapsed lightweight who had a set of my own 370-375 original Fat Smoothies a while back - set at their minimum length, I found them wonderful in still conditions, particularly for starts - they just gripped and went. On balance after a while I would have probably preferred the later 368-373 version to give me somewhere to go when it was windy or a strong current on our home river. Someone rowing in a double during a fortnight when I was away from the boathouse borrowed my blades and decided (at the behest of their coach) to increase them to 374 to match the actual length of her partner's "conventional" Slick hatchet Crokers - without telling me. The blades were then left in that state on my shelf.

Next time I went for a row, I had a horrific time - couldn't start without lifting myself off the seat and feeling really out of sorts. Couldn't rate higher than about 18 and it was a struggle. I assumed it was just me not being properly hydrated so soldiered on a bit. Managed to row around half an hour before my back was giving me all sorts of aches and pains, so I eventually took the boat home. It was only when I was washing the blades that I noticed the extended handles and moved collars and the penny dropped. I asked the person who used my blades if she'd noticed a difference, and she commented that they'd had a horrible row with similar symptoms, which she'd never experienced using them in my single before.

In a nutshell - they really do row 4-5cm longer than their actual length. The biggest hurdle is convincing dyed in the wool old-school rowers in the same boathouse who think that they know measurements that this is actually the case and not just C2 marketing smoke and mirrors. It is easy to be cynical about a lot of claims out there, but this one seems to hold out in action.

[Jim Dwyer]

The CII booth will cut 2cm off of the handles and glue new plugs for you to
shorten your oars.
I had that done at the HOC regatta. You can do it yourself if you like as
well. They will send you everything you need.

I have 2 sets of Fat Smoothies with the skinny shafts:
276-281 length range, fat 2 vortex blades and medium stiffness skinny
shafts. (bought used and shortened 2 cm)
275-280 length range, fat 2 vortex blades and extra soft stiffness skinny
shafts.



Jim

wrote in message
news:aed046d7-857c-46eb...@googlegroups.com...

[Jim Dwyer]

Do you mean 270-275 cm?

wrote in message
news:aed046d7-857c-46eb...@googlegroups.com...

[gsl...@gmail.com]

It is universally agreed that the Fat2's should be rowed shorter than big blades. From that can conclude that the Fat2's will "feel heavier" and grip the water better at the catch. That may mean they are more efficient for some definition of efficient. It may or may not mean they are faster.

[stan...@gmail.com]

On Thursday, December 17, 2015 at 10:29:17 PM UTC, gsl...@gmail.com wrote:
> On Thursday, December 17, 2015 at 2:01:00 AM UTC-8, Alistair Browne wrote:
> > Although there is a danger of opening a can of worms...
> >
> > The accepted wisdom seems to be that the C2 Fat2 spoon requires a much shorter overall length because it is so much more efficient.
> >
> > My reaction to this, with no actual experience of using the Fat2 blades, is that it seems unlikely that any big blade is so inefficient that the Fat2 can make such a big difference.
> >
> > Am I wrong?
> >
> > Thanks,
> > Alistair

Having used them a great deal since 2010 I would agree.

The so called "swiss" rigging of short inboards and tight spans to maximise catch angle is tricky to get right. It's very easy to underwear and end up just spinning the wheels. Rowing illustrated has pages devoted to debating the set up.

I'm currently using a more conventional rig with the Fats set 6cm shorter than I would set normal blades and that works very well and numbers seem transferable i.e. you can use the normal set up you would pick for whatever boat class but just make the length -6cm.

For the record I'm now a tired parent and MasB lwt but also not very far off the ergs I was pulling when winning UK nat champs.

[robin_d...@hotmail.com]

Whoops, yes this shows you what happens when someone "old school who thinks they know the numbers" have sold their scull and dedicated themselves to parenthood for the last 4 years instead of hanging around a boathouse.... :)

On Thursday, December 17, 2015 at 7:36:45 PM UTC, Jim wrote:
> Do you mean 270-275 cm?
>

[carl]

May I offer, for Xmas, Carl's simple rule?

"The easier it feels to pull an oar of given overall dimensions, the
lower is its propulsive efficiency."

Let me explain:
When we say it's easier to pull an oar, we mean that we can pull it
faster from catch to finish. Unfortunately, that faster motion can come
only from increased blade slip. All slip is work done for no propulsive
return. If we could measure the variation of slip & force throughout
the stroke, then we could define the work lost to slip as the integral
of force applied x distance of slip. Work lost to slip is thus crudely
related to slip distance, or to the reduction in stroke duration.

If we adjust spread, oar length or inboard/outboard ratio to try to
achieve the "feel" to which we are most accustomed, then we may also be
reducing or eliminating whatever advantage we might have been getting
from a less slippy blade.

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

[gsl...@gmail.com]

On Sunday, December 20, 2015 at 10:58:23 AM UTC-8, carl wrote:
> "The easier it feels to pull an oar of given overall dimensions, the
> lower is its propulsive efficiency."

What people mostly feel is the load at the catch and initial part of the dirve. It is not obvious to me that a blade that is more efficient at the catch will necessarily be more efficient near the release.
The bigger blades will also have more wind resistance and make it more difficult to row cleanly in rough water. So while they have greater propulsive efficiency, they may not be faster in many/most conditions when you consider what happens on the recover.
Assuming the Fat2's need to be about 6 cm (or ~3%) shorter and that translates to about 3% more efficient, then we would expect a speed increase of about 1% or 3-4 seconds in a six minute race all other things being equal. That should be measurable. They have been around for a number of years now, yet what percentage of internationally competitive crews have been rowing with them? In casual viewing I've noticed very few. Some crews even opt for even less "efficient blades": the smoothie 2 or even the big blade over the smoothie vortex.

Not saying that the Fat2's aren't fine blades and I know a number of people who love them. I've thought they were fine blades when I've tried them, I just can't tell at all if I am any faster with them.

[carl]

I would suggest that the fact that the set-up for these blades differs
from that for other blades indicates that rowers & coaches presume that
an oar which feels different gets adjusted until it feels much like any
other blade.

I would expect that, in all probability, this results in its propulsive
efficiency ending up much the same as for all other blades.

That we do this is unsurprising since rowing elevates touch & feel to
quasi-scientific status & rules out adjusting technique to the
requirements of the equipment. If it feels "wrong", then we'd much
rather change everything until it feels "right" rather than make due
allowance in our technique for a stroke whose longer-duration is due to
its reduced slip & greater propulsive efficiency.

In short, as ever we kid ourselves that slip provides gearing.

An instance of a sister sport which did successfully adjust to a (much
more radical) change in equipment is kayaking. With the arrival of the
"Wing" paddle, of totally different shape to the oar-like paddles used
hitherto, kayakers who wanted to win learned a new technique. Where
previously they had dug the blade in and drawn sternwards, using the
blade as relatively simple stalled baffle, when using the wings their
action became more of a sideways sweep. This was necessary because the
the wing paddle acts as a foil (hence its name), relying upon the lift
generated by its rapid sideways motion rather than on the sternwards
drag of the traditional paddle blade.

One consequence is that the wing paddle, moving sideways to generate
lift, can exit the water ahead of where it entered.

[thomas....@googlemail.com]

> That we do this is unsurprising since rowing elevates touch & feel to
> quasi-scientific status & rules out adjusting technique to the
> requirements of the equipment. If it feels "wrong", then we'd much
> rather change everything until it feels "right" rather than make due
> allowance in our technique for a stroke whose longer-duration is due to
> its reduced slip & greater propulsive efficiency.
>
> In short, as ever we kid ourselves that slip provides gearing.

How would we adjust our technique to take better advantage of stroke efficiency then? Are you referring to what you have suggested before in rowing deeper through the middle of the stroke to reduce the amount of slip during the stroke? If so the variable pitch offered by the oarinspired intelligates may be interesting/useful to that end as it would mean you could adjust the pitch through the stroke to try and reduce slip/increase efficiency through the whole stroke

http://www.oarinspired.com/variable-pitch/

You'd just have to hope your fitness is able to cope with the extra load tho I guess!

[Kit Davies]

One obvious option is increasing the "duty cycle" of the stroke by
learning to recover more quickly. A kind of "Pulse Width Modulation" for
rowing. We tend to do this at the start anyway. Extending it to the
body of the race is doable but takes skill. It is one of the things Bond
& Murray seem to do better than anyone else.

Kit

[thomas....@googlemail.com]

Think you accidentally replied just to me and not the group (im not actually sure how you even do that?) But I have copied here what you said and commented after

>I don't think there's any need to invoke variable pitch just to row a bit >deeper, you just do it. Indeed, using pitch to that end might be an >unnecessary complication.

>Nor do you need to be stronger or more fit - there is only extra load if >you choose to apply it. Yes, if you remain wedded to a particular stroke >"feel" & wish to limit stroke duration you may very well try to increase >the load, but then you'd be missing the whole point of the more efficient >stroke - that it _has_ to take longer for the same arc.

>Rowing is mired in emotive nonsense about "getting the blade through >faster". This kids us that we can & should pull the blade _through_ the >water. No, the less slip the better. But get used to how that feels & >allow a little more time - in fact, allow all the time it takes to go from >catch to finish as you won't be able to reduce it.

>And at that point I refer you to Kit's very apposite post of today re >recovery time.

I agree with Kits point, and yours - however I have some questions that may help me understand better the whole stroke -

If you compare two set ups, one of which is has less slip than the other, it is a given that it will take longer to finish the stroke with the setup of less slip OR you will need to apply more force in order to make it take the same amount of time as the setup with more slip - what timescales are we talking here for the "longer" amount of time, is it known?

Added into that, how does this longer time taken to finish the stroke affect the boat speed/acceleration? Since the boat reaches its top speed at the early part of the recovery/and continues to accelerate through the recovery/only starts decelerating when you apply force to the footplate coming into the catch, does than mean there needs to be a balance between having a good amount of time for the drive to the recovery - i.e. having "no slip" would not be bio mechanically the best and instead there is a "sweet spot"?

[wmar...@gmail.com]

There's a point where the rigging gets just "too heavy." If you rig for length at the catch, with the aim of getting the best lift and reactive thrust from the blade during the early part of the stroke, you will indeed find the stroke heavier. This will increase the time it takes to complete the drive, and decrease the time available, at any stroke rate, for the recovery. By reducing the outboard length of the blade, while still rigging for length at the catch (shorter spread/span, shorter inboards correspondingly, foot-stretchers farther astern or rigger farther forward) one can still have a relatively high stroke rate.

I think there is a sweet spot - how to find it is another question, but if you're coaching, or if you're rowing and the crew is unable to sustain a "body" stroke rate in the mid 30s, then, for their abilities (assuming a couple of seasons of training under their belts) they're rigged too heavy. "Old School" likes a low stroke rate, but higher stroke rates give faster boat speed overall by virtue of a greater time overall spent accelerating the movement system, even though the forces applied at higher stroke rates are lower than those applied at lower stroke rates. (Celentano, et al., Mechanical aspects of rowing. J. Applied Physiology, 36(6):642-647, 1974.)
If you think about it in a more simplistic way - if you clear (say) 11 metres per stroke at 28/minute, you get 308 m/minute, and (say) 9.5 metres/stroke at 36, you get 342 m/minute... While purists might like to look at the rhythm/ratio of the 28/minute crew, I'd rather be the tired folks, 34 metres ahead of the "good looking" crew pulling their guts out but not able to get the rating up. These numbers are made up, the differences are probably exaggerated, and not based on any measurements, but the principle is - greater impulse per minute in racing is perhaps more important than greater impulse per stroke... The "system" (boat, crew, oars) goes faster at higher rates: there's less time spent with the oars out of the water (i.e., more time in propulsion), and the crew gets to stop sooner than the slower crews in the race... (do the armpit shot, and collapse)...

Volker Nolte's been talking about how shorter oars are more efficient for years...

[carl]

Oh dear! Ever since a recent Thunderbird upgrade (& why do they keep
messing with what worked perfectly well hitherto?), when responding to
RSR you get the options "Reply" & "Followup" in boxes side by side, &
"Reply" & "Forward" for emails. When snatching a mo to respond on RSR
my knee-jerk assumes I'm replying to RSR, not to you in person, so I
flick the "Reply" button. Ooops!

Similar nonsense with Android phones. Having plugged in a USB lead to
download photos for the last couple of years, a recent upgrade left us
staring at an empty screen where the folders on the phone should be.
Searching the web, we find others with the same problem, unable to
download their snaps, but no explanation of how to resolve it. Thanks!
With the "help of a friend" the problem was solved, but the solution
is idiotic, pointless & probably totally "granny-proof", done for no
discernible reason than to prove the sociopathic tendencies of the
programmers & waste huge amounts of time for us dimmer Android users at
large, who should _not_ have to re-learn & fight with their toys after
every so-called upgrade.

Anyway, this is the season of goodwill, so I'll try to be nice.

Thomas, I thank you for posting my post into the correct place, i.e. not
into your in-box yet again. But don't shout about it or someone will
think we've something going on between us ;)

Now to answer your well-put questions (checks first for smoke still
issuing from ears):

Comparing setups -
Suppose one oar is 80% efficient & the other is 82% efficient, & that
your stroke duration is around 0.8 seconds? Then one might, as
first-order approximation, expect a difference in stroke durations of
~0.02 seconds.

That sounds like almost nothing - it will change a rate of 30 by just 1%
(0.3 spm). So, you might say, what's the big deal?

Well, we have a very sensitive awareness of timing (doesn't always show
when we're rowing together or on the dance floor), & that 0.02 seconds
represents a 2.5% change in stroke duration. Our natural response is to
try to "correct" it, so we pull harder, then grumble that "those oars
feel too heavy". Reducing that slower stroke time of the more efficient
oar (or stroke technique) to that of the less-efficient oar will require
a boat-speed increase of 2.5%, demanding an increase in power of ~8%, so
no amount of pulling harder will cancel out that increased duration.

On the other hand, you're already doing more useful work - ~1.5% more
despite that small rate decrease - so why try to change it? If you do
want to restore that 0.3spm loss, then reduce recovery time from 1.2 to
1.18 sec by moving more smoothly over the knees & cutting out any dwell
over frontstops.

Next, to your speed/acceleration question -
Only 1 thing really matters, & that's the total amount of useful work
done per unit of time - the net propulsive power of the rower/oar system
after all losses. our objective is not to accelerate the boat but to
keep its average speed high. That a more efficient oar wastes less
energy per stroke &, as I hope I've shown, that results in more
propulsive work per unit of time, should mean the boat goes a little
faster overall.

We don't want to accelerate the boat during recovery to above the speed
it had at the moment of blade extraction as any extra speed incurs a
disproportionate cost in energy dissipation. Rather, we want during the
recovery to sustain its speed as far as possible without over-speeding,
when we are in effect returning stored energy from body to boat to
overcome the frictional drag on the boat.

In reality, the boat somewhat decelerates during the recovery, & it does
check around the catch, but I'm alarmed by the suggestion that we are
actively & contentedly checking the boat by foot pressure on the
stretcher as we approach the catch. That sounds dangerously like the
notion of applying "slide control" as you come forward, as if your
flimsy boat had the mass/inertia to be able to slow your much larger
mass before you take the catch. When rowing it is the boat that
oscillates to & from beneath you, & you glide smoothly on

Perhaps that's a little too deep for this discussion? I realise that
I'm battling against 150 years of received wisdom when dismissing the
notion of slide control, even today, but suffice to say that I see no
reason to suppose there could be a "greater slip/lower efficiency" sweet
spot which one ought to seek out. Discarding efficiency in search of an
illusory re-balancing of accelerations seems, to me, to lack any
foundation in reality. Perhaps a case of what some might call
"overthinking" a problem?

Anyway, I promise to try not to press the wrong button ever again - but
I can't guarantee that.

[Henry Law]

On 23/12/15 00:03, carl wrote:
> That sounds dangerously like the notion of applying "slide control" as
> you come forward, as if your flimsy boat had the mass/inertia to be able
> to slow your much larger mass before you take the catch.

No, no, no, Carl. The boat has enough mass/inertia to move itself
underneath you, so that you "come up the slide" without having to exert
any force. I know, because a BR instructor told me so, and was so
convinced of his position that he wouldn't allow me to present what I
laughably thought was my Newtonian understanding of the matter.

--

Henry Law Manchester, England

[thomas....@googlemail.com]

> Comparing setups -
> Suppose one oar is 80% efficient & the other is 82% efficient, & that
> your stroke duration is around 0.8 seconds? Then one might, as
> first-order approximation, expect a difference in stroke durations of
> ~0.02 seconds.
>
> That sounds like almost nothing - it will change a rate of 30 by just 1%
> (0.3 spm). So, you might say, what's the big deal?
>
> Well, we have a very sensitive awareness of timing (doesn't always show
> when we're rowing together or on the dance floor), & that 0.02 seconds
> represents a 2.5% change in stroke duration. Our natural response is to
> try to "correct" it, so we pull harder, then grumble that "those oars
> feel too heavy". Reducing that slower stroke time of the more efficient
> oar (or stroke technique) to that of the less-efficient oar will require
> a boat-speed increase of 2.5%, demanding an increase in power of ~8%, so
> no amount of pulling harder will cancel out that increased duration.
>
> On the other hand, you're already doing more useful work - ~1.5% more
> despite that small rate decrease - so why try to change it? If you do
> want to restore that 0.3spm loss, then reduce recovery time from 1.2 to
> 1.18 sec by moving more smoothly over the knees & cutting out any dwell
> over frontstops.

Thanks for the clarification with values, as you say it would appear that during the drive phase you would not be losing out too much if you allowed the drive phase to take longer with the more efficient oar - it makes sense to me as well that your clarification of the extra 8% energy required to make the drive time the same as with the less efficient oar would be why people talk about feeling "overloaded" and "burnt out" if they are trying to row the same way with a more efficient oar than they were before

> Next, to your speed/acceleration question -
> Only 1 thing really matters, & that's the total amount of useful work
> done per unit of time - the net propulsive power of the rower/oar system
> after all losses. our objective is not to accelerate the boat but to
> keep its average speed high. That a more efficient oar wastes less
> energy per stroke &, as I hope I've shown, that results in more
> propulsive work per unit of time, should mean the boat goes a little
> faster overall.
>
> We don't want to accelerate the boat during recovery to above the speed
> it had at the moment of blade extraction as any extra speed incurs a
> disproportionate cost in energy dissipation. Rather, we want during the
> recovery to sustain its speed as far as possible without over-speeding,
> when we are in effect returning stored energy from body to boat to
> overcome the frictional drag on the boat.

> In reality, the boat somewhat decelerates during the recovery, & it does
> check around the catch, but I'm alarmed by the suggestion that we are
> actively & contentedly checking the boat by foot pressure on the
> stretcher as we approach the catch. That sounds dangerously like the
> notion of applying "slide control" as you come forward, as if your
> flimsy boat had the mass/inertia to be able to slow your much larger
> mass before you take the catch. When rowing it is the boat that
> oscillates to & from beneath you, & you glide smoothly on

We might not want to accelerate the boat during the recovery and overly check it at the catch, but according to data collected by BioRow (and seen myself using the Rowing in Motion app), that is what happens.

http://www.biorow.com/RBN_en_2012_files/2012RowBiomNews11.pdf

Generally during a rowing stroke (particularly at rate where you are forcibly changing the direction of the boat at the catch and the finish) there is a tendency for the boat to accelerate as you move through the recovery, this acceleration stops as soon as you apply force to the footplate as you approach the catch so no alarm necessary, I agree the aim is to try not to control the recovery at all, but instead draw the boat towards you - this does mean that there will be a sharper deceleration at the catch

In my head at least having a slightly longer recovery time could be seen as a benefit since you have more time to recover/accelerate the boat during the recovery as seen which would support the idea of this "sweet spot" of gearing finding the best balance between drive time and recovery time - Although this would need investigating to see if the theory held out, if (for example) the boat speed at release is considerably faster for the more efficient rig/longer drive time then I can see the theory being incorrect

[thomas....@googlemail.com]

Also this paper from BioRow raised an interesting point while it was testing a number of different blade lengths to see if there was an ideal blade length for the height of the rower

http://www.biorow.com/RBN_en_2011_files/2011RowBiomNews04.pdf

On the left hand side, half way down the page :

The average forces were quite similar in all rigging settings (3% difference), but slower handle velocity caused a proportionally 10% lower power production. This resulted in a 3.5% slower boat speed, even though the blade efficiency was 2% higher at the shortest rigging

So despite the increase in blade efficiency due to the rig, and the same measurements of force on the blade, the measured power actually decreased due to the reduction in velocity. Obviously power wouldn't keep increasing till you reached 0% efficiency so this would also suggest that there may be a "sweet spot" of drive time/blade efficiency for optimum performance?

[carl]

What we see in that Biorow newsletter is interesting, but is it ideal?

It looks to me as if the boat is being beaten up, with much effort going
into a fast recovery & a big price being paid as a result, with erratic
accelerations & a prolonged catch-region check.

Please remember, first, that the line for zero acceleration is not
necessarily, nor likely to be, the marker for the average boat speed.
Without seeing boat speeds it is harder to comment meaningfully. Boat
speed response will lag well behind the acceleration curve, & that could
cause you some confusion? I could chew the data to derive speeds, but
there may be better things for me to do.

Essentially we seeing here what some rowers do, so a bit of a doctrinal
cloud hangs over whatever one then says. Our discussion of blade
efficiencies ought, rather, to be about what rowers might do better.
Those graphs represent currently-favoured techniques, & it would be
possible to show other acceleration (& velocity) curves which tell
different tales. We do not seem to see coaching aiming at flattening
out profiles of velocity, despite the availability of data & a growing
awareness that this might be no bad thing.

During recovery, there being no external propulsive interaction, you can
only do work between body & boat & extending the recovery duration
apparently gains you nothing.

[thomas....@googlemail.com]

> What we see in that Biorow newsletter is interesting, but is it ideal?
>
> It looks to me as if the boat is being beaten up, with much effort going
> into a fast recovery & a big price being paid as a result, with erratic
> accelerations & a prolonged catch-region check.

Always difficult to say what is ideal, but if the ideal is to go the fastest then looking at the Olympic Champions curves is probably a good place to start - The suggestion being that the curve in the PDF is from the 2008 Aussie pair who are often held up as a good technical benchmark to emulate

> Please remember, first, that the line for zero acceleration is not
> necessarily, nor likely to be, the marker for the average boat speed.
> Without seeing boat speeds it is harder to comment meaningfully. Boat
> speed response will lag well behind the acceleration curve, & that could
> cause you some confusion? I could chew the data to derive speeds, but
> there may be better things for me to do.

True, acceleration doesn't show velocity but when measuring boats with telemetry it usually shows the velocity is highest at a point during the recovery (for example see the PDF linked below) - Graph 4 shows the boats relative velocity is the highest during the recovery and lowest during most of the drive (except the very end of the drive)

http://www.biorow.com/RBN_en_2012_files/2012RowBiomNews05.pdf

This report is actually quite useful regarding the question of gearing as it turns out, it is of two scullers (1 and 2) who are measured at the same rate but sculler 2 rows a longer arc in the water which means to keep the same rate, he has to have a shorter recovery time than sculler 1. From Telemetry measurements, sculler 1 was actually applying more force than sculler 2 but sculler had a higher power due to longer stroke and overall sculler 2 was considerably faster than sculler 1.

Downsides to this report are its not that clear what rig each sculler was on, where they the same? Also what blades were they using, were they also the same? The report concludes that stroke length needs to be maintained as first priority, but this still leaves me with the question on ideal blade efficiency/ideal drive to recovery time which would be the next step to investigate - i.e. if sculler 2 was going faster due to having a longer arc length, but power output could be further increased by reducing blade efficiency/increasing drive time velocity (as shown in the earlier linked document linked again below), would the sculler go faster with less efficient blades? Finding the right balance for maximal speed?

http://www.biorow.com/RBN_en_2011_files/2011RowBiomNews04.pdf

>Essentially we seeing here what some rowers do, so a bit of a doctrinal
>cloud hangs over whatever one then says. Our discussion of blade
>efficiencies ought, rather, to be about what rowers might do better.
>Those graphs represent currently-favoured techniques, & it would be
>possible to show other acceleration (& velocity) curves which tell
>different tales. We do not seem to see coaching aiming at flattening
>out profiles of velocity, despite the availability of data & a growing
>awareness that this might be no bad thing.

True, rowing is an annoyingly private sport at the top end which makes looking at wider data difficult, which you would need to do in order to look for trends/suggestions as to what unorthodox things you may try in order to get the best boat speed possible

[gsl...@gmail.com]

Not really buying much of the logic here.

We make adjustments much larger all the time. Changes in wind can have a much bigger effect on stroke rating and feeling during any given outing. So can rowing a boat with a different number of people in it or just with different partners in the same boat.

When the Fat2 came out people rowed them longer than they do now. People tried them longer and seamed to have settled on something shorter.

Rowers balance/adjust handle force/speed and power output depending on the situation. Force the gearing/load out of what is ideal for the individual and performance will suffer.

To repeat my earlier post, more hydrodynamically efficient blades are only faster if they don't cause you to loose time due to something else such as wind resistance or by making it difficult to row cleanly in rough water.

Carl, it would be easy to interpret your posts in this thread as advocating for the Fat2 blades, which are commonly believed to be more efficient. You have often questioned the belief that the newer blade shapes are faster. Care to clarify?

[carl]

On 23/12/2015 20:51, gsl...@gmail.com wrote:
> Carl, it would be easy to interpret your posts in this thread as advocating for the Fat2 blades, which are commonly believed to be more efficient. You have often questioned the belief that the newer blade shapes are faster. Care to clarify?

Hi Greg -

I had no intention of advocating one blade over any other, & I'm sorry
if I in any way gave that impression. I was talking about a more & a
less efficient blade, but never conflating those with known makes &
types. Similarly, my suggestions of blade efficiency were in no way
related to any particular blade.

In the past I've suggested that blade types might be more of a marketing
ploy than a performance enhancement, & I know that tests done on the
Potomac a few years back seemed to suggest that modern blades were
actually no more efficient than Macon-style blades. It could be not so
much the tool you use as the way that you use it.

Like you, it does perturb me that we finnick with few-millimetre rigging
changes in response to weather changes while the weather throws really
big changes at us. But then I've always said that the most adjustable
piece of kit in the boat is the rower, who can substantially adjust his
or her gearing according to conditions just by varying catch & finish
lengths.

[gsl...@gmail.com]

> In the past I've suggested that blade types might be more of a marketing
> ploy than a performance enhancement, & I know that tests done on the
> Potomac a few years back seemed to suggest that modern blades were
> actually no more efficient than Macon-style blades.

Not sure I agree with you here either. It comes down to the definition of efficient. I need some convincing that the Macon's don't slip more than more modern blades--which has been the implicit and sometimes explicit definition of efficiency used in this thread.

That is not to say that modern blades are faster than Macon's or that Fat2's are faster than Smoothies. This requires more proof.