What is gained by shortening the inboard?
Charles Carroll
I have had a lot of conversation lately with scullers who are rigging
with reduced inboards. Instead of the standard formula, Spread/2 + 8
cm, they are advocating using a Spread/2 + 6 cm.
What is gained by shortening the inboard?
An oar is a lever, and when you apply a force to one end of a lever,
you exert a torque, which is defined as the product of two quantities:
the length of the arm you're pushing on and the amount of force you're
applying.
So, doesn't the length of the inboard determine the torque? In other
words, by shortening the inboard you reduce torque - this same torque
that acts on the far end of the lever (i.e. the blade).
Now why would any sculler or rower want to reduce torque anymore than
is absolutely necessary? Wouldn't this be equivalent to saying that
you want to row with less power?
Warmest regards,
Charles
Steven M-M
wrote:
As someone not blessed with a tall, lanky rower's body, I shorten my
inboard and overall length (86/285.5) so that I can move the foot
stretcher to the stern, achieve a good catch angle, and still have
room for a comfortable release.
Steven M-M
ATP
"Charles Carroll" <charles...@comcast.net> wrote in message
news:97rt5f...@mid.individual.net...
Look at the relationship between torque, power and energy:
http://en.wikipedia.org/wiki/Torque
Carl Douglas
And with an oar we do not generate torque, since we are not twisting a
shaft. A lever will only generate torque when the couple or moment
which you apply has an object upon which it can generate a net rotatin
effect. At the pin there is zero torque, unless the oarlock bushes are
binding on the pins. Each oar does generate torque on the whole boat,
but the oar on the other side generates a countervailing torque to
cancel that out - or we'd be rowing in circles.
What we are interested in doing with that stick we term "the oar" is
applying a force at the blade & benefitting from its matching reaction
against the water. That it is a funny old lever which we can never,
much as we'd like to, categorise into any one classic category, does not
mean that we wish to generate a net torque. Our lever simply transmits
&, according to its proportions, including pin position, it gears down
the force we apply at the handle to become the resulting force at the blade.
We fiddle around with inboard & outboard as one of our somewhat blind
games of gearing adjustment, meanwhile often forgetting that the most
controllable gearing-related variable is stroke length. A longer stroke
gives us automatically a more severe gearing but at the same time gives
increased access to the more efficient end parts of that stroke. It is
more severely geared only because, being longer, it takes longer to
complete. So we reckon the resulting longer stroke is "heavier", but
only because we are determined to complete it in the same time as a
shorter stroke & unwilling to accept a) that this may be folly & b) that
the adverse effect on rating is immediately solved by a smoother
recovery & a quicker catch.
By changing inboard we do again change leverage (one component of
gearing) but, because changing inboard for the same hand travel will
also give a longer stroke with its own hardened gearing effect, we are
really changing 2 gearing factors at once.
Remember that the sole object of rigging for the rowing stroke is to set
up the geometrical parameters in such a way that will allow us to make
the best use of our own feeble physiques - i.e. generate the optimum
level of net propulsive power (after deducting all the hydrodynamic
inefficiencies of the processes surrounding the blade).
That optimum level is that which allows us to extract the greatest
amount of net propulsive power at a steady rate over the set race or
training distance - i.e. without loss of control or technique before the
end. Changes in gearing - either the geometric adjustments which so
obsess most of us but which might be less important than we like to
imagine, or in stroke length & resulting stroke/recovery rhythm & force
profiles, etc., (which may well have greater relevance) - have to be
made which allow us to achieve our objective.
With a car or a bike it seems pretty simple to pick the right gearing
for a given task, but even there we fool ourselves if we fail to accept
that the right gearing depends intricately on many factors including
gradient, the relationship between engine power & its speed, &
extraneous features such as wind force & direction. On a bike or in a
car we can continuously adjust gearing & rpm. In a boat, during a race,
we can't adjust the seemingly obvious gearing parameters of inboard,
outboard & spread but instead we have compete control over rating,
stroke length, recovery time & load levels & distribution through the
stroke.
Thus, if you try to blast off at an unsustainable power output you will
fade horribly & certainly not achieve the best possible overall race
speed. If you simply expect a small change in inboard length to solve
your gearing questions, you are bound to be wrong. If you assume the
same rate, load & length will work when you round a corner into a
breeze, you are self-deluding. And so it goes on.
Thus there are no simple answers, no right & no wrong. Circumstances
continually alter cases. And if you are unwilling to make continual
adjustments between strokes according to your own & the external
conditions, you cannot be a complete rower.
That's why I so applauded Zibi's recent observations on the relationship
between the good & the best. The best is always a moving target &,
until we recognise the multidimensional physical aspects of rowing the
good race, we have slim chance of ever rowing our truly best possible
race or piece of work.
Remember: the most adaptable & adjustable piece of kit we possess is the
intelligent & well-informed combination of brain & body.
Cheers -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: http://tinyurl.com/2tqujf
Email: ca...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)
Zbigniew A.
[...]
> Now why would any sculler or rower want to reduce torque anymore than is
> absolutely necessary? Wouldn't this be equivalent to saying that you
> want to row with less power?
Why would any bicyclist want to shift from a bigger to a smaller rear
sprocket (cog)?
--
Yours Virtually, Zibi
Charles Carroll
> inboard and overall length (86/285.5) so that I can move the foot
> stretcher to the stern, achieve a good catch angle, and still have
> room for a comfortable release.
Steven,
About a year ago, much for the same reasons, I did pretty much the
same thing. I changed my rigging to 158/282/86.
By using an 86 cm Inboard with a 196 Outboard I gained a sort of
medium gearing, maybe just a tad on the heavy side. I chose this ratio
because I thought it would help me increase my rating while preserving
a good catch angle and comfortable release.
Initially, as I became accustomed to it, I found myself liking this
rigging very much. I did indeed find it easier to rate higher and my
catch angle and release were acceptable for someone my size. I am
roughly 172 cm in height and 70 kg in weight.
But even though I was relatively satisfied with this rigging, I couldn't
stop wondering what I was losing. And then one day, as I was perusing
Dr. Kleshnev's newsletters, I realized what it might be. Just as
everyone said it would, shortening the Inboard and overall length of
my oars had enabled me to scull at higher rates. But I began to
suspect that these rates were being produced not in a quicker
recovery, but in a shorter drive time. And that suspicion led me to
begin yet another round of rigging experiments.
Lengthening the Spread 2 cm, lengthening Total Oar Length 6 cm, using
a standard formula to arrive at Inboard (Spread/2 + 8 cm) - all these
changes resulted in an Outboard of 200 cm. This rigging is completely
standard, what Valery Kleshnev calls "Traditional" rather than
"Innovative."
What's more, with the changes I made to the rigging I achieved my
goal. The overall result is a tad longer drive time. Of course it is
also harder to rate as high. But this was to be expected.
Another problem is that with the old rigging I became accustomed to
sculling in a certain rhythm. The new rigging changes with a longer
drive time mean that I have to re-accustom myself to a new rhythm, the
standard measure of rhythm being the ratio of drive time to total
cycle time. So this is what I am now working on. I suspect it is going
to take months before I find this new rhythm. But it seems like a
useful goal.
Warmest regards,
Charles
Tinus
wrote:
Standards are often wrong because people are different.
Charles Carroll
Further to the discussion, here are some notes from Kleshnev and
Atkinsopht that may possibly interest you.
Cordially,
Charles
__________________
Increase in Average Rowing Power correlates with Heavier Gearing
In the May 2004 Rowing Biomechanics Newsletter Valery Kleshnev
reported on "the handle force, velocity and power during rowing
(single scull) with normal gearing (88cm inboard, 290cm oar length),
lighter (3cm shorter outboard) and heavier gearing (3cm longer
outboard). Stroke rate was 32-33str/mim."
"If we compare the normal and light gearing, then the main difference
in the force curves is during the second half of the drive, where the
force was about 40N less with lighter gearing. On the contrary, handle
velocity was about 0.2m/s higher during the first half, although it
was the same "after the pin". These changes were opposite during the
heavier gearing. The rower apply about 40N higher force at the same
speed "before pin", but then the handle speed was 0.1m/s slower and
the force is similar to the normal gearing. The drive time appeared to
be 0.06s longer with heavier gearing.
"Peak power was similar during the normal and lighter gearing,
although achieved earlier during the lighter gearing. Peak power was
lower during the heavier gearing, but average rowing power was the
highest (495W), because of longer drive time. It was lower during the
lighter gearing (491W) and the lowest during the normal gearing
(481W)."
Kleshnev concluded: "Rowing with shortened outboard will make the
gearing ratio lighter and increase the speed of the drive, but
decrease force application. On the contrary, increasing of the
outboard will make the gearing heavier and change force/velocity ratio
in other direction."
___________________
Shorter vs. Longer Outboard
"For a given rower's strength-as measured by the peak force of his
oarhandle pull-there is, for every oarhandle length (inboard lever),
an optimum outboard lever. If the outboard lever is long the
propulsive reaction is weak, but the wasteful blade slip is also low;
and if short the blade slip loss is high but so, too, is the
propulsive force. There is therefore an optimum lever (or blade
surface) which balances propulsion and slip." -Atkinsopht, "Rower
Strength and Oar Length,"
_________________
Blade Surface Area and Blade Efficiency
"The ROWING model seems to indicate that increased blade surface has
potential for improving blade efficiency. Increase in surface (drag)
reduces slip thus increasing the advance of the shell per
sweep." -Atkinsopht, "Oarblade Surface Area,"
____________
THE ROLE OF SPAN AND SPREAD
"Span and spread have no role to play in the determination of oar
lever (or "load") ratio. There may be something to be said for
altering spread in conjunction with inboard in order to preserve a
handle geometry the rower may have become accustomed to. That is,
change inboard and span or spread always by similar amounts and in
compensating directions." -Atkinsopht, "Rigging Notes"
Steven M-M
wrote:
Charles,
You and I are close in size, although I'm ~6kg heavier. I don't fuss
much with rigging. I've been sculling with spread = 159, oars 86.5,286
for ~ 10 years. This year I experimented with tightening the spread a
little to 158.6 and needed to shorten the inboard to 86 to keep my
releases comfortable. This new rig feels great and I do think I'm
getting a touch more catch angle & a hint of more speed. I'm
comfortable at stroke rates from 16 to 40 and am able to hold my
normal race cadences at various distances. I'm a strong believer in
the placebo effect, but for now I like this new, slightly altered set
up.
Steven
Charles Carroll
You never fuss much with rigging! Oh fortunate man to be so blessed by
the Gods!
I have never been able to settle on a rigging that I am happy with.
The other day in the Boathouse Liz Stone told someone that I change my
rigging every two weeks. ;) Arrrrrgh!
In the last two weeks, however, I have been happier with my rigging
than I can recall ever having been. So maybe this rigging is "a
keeper." I guess it all depends on if I can find the right rhythm with
it.
By the way, I am amazed that you can get your stroke rate up to 40spm.
How does it look? When you take lessons from Gordon, have you sculled
at this rate? I only have a lesson with Gordon once a year. The last
two years he has told me that I lose my technique as I go past 32spm.
Usually this lesson is in late August. In November Ric Ricci is in
town and I have a lesson with him. Ric says the same thing that Gordon
says -- that my techniques degenerates when I try to go over 32. I am
just going to have to try harder.
Warmest regards,
Charles
Steven M-M
wrote:
There are much better sources of advice than me, but since you
asked.... I would find a rig that is comfortable for you and don't
worry about all the technical nuances. By comfortable, I mean you can
get the blades in and out easily. When in doubt make things easier,
not harder; a little lighter is better than too heavy. There is no
secret to high stroke rates, but if all you ever do is row between SR
18-26, then 32+ is going to feel like a dangerous place. 32+ should
still feel slow; remember at 40 you're still a little more than 1/2
the cadence of an easy bike ride. Every row, when you're feeling
warmed up but not tired, take the SR up to 28, 30, 32, 34... for up to
maybe 20 strokes. Don't go for speed just clean releases and,
secondarily, clean entries. Relax, just tap it along. As soon as you
feel sloppy or out of control, drop it back a stroke or two. As soon
as you feel tense, stop. Once you feel relaxed at the higher stroke
rate, start adding power. Use 15-20 higher cadence strokes for fun, as
a way to break up the monotony of SR 18-22 slogs.
Tink
I, like you, am a little pre-occupied by rigging. It is another
factor that we can vary to ensure we row with our best performance. I
remember a quote by someone from a rowing book (citation needed) where
they said rigging can make a difference to how fast we go and
therefore why wouldn't we spend a bit of time to make sure it is right
(paraphrasing).
I think rigging is a valuable thing to be pre-occupied by, even if I
probably take it too far by re-assessing my rigging regularly based on
my latest and greatest ideas. I am surprised how many people do not
check their rigging on at least an annual basis - things become bent
and worn over time and maybe need to be adjusted to bring them back to
where they started.
I'm starting to think however, that it has less effect than I'd
previously thought.
I infer from the Kleshnev rigging calculator that your speed is
basically dependant on your fitness and strength (ignoring technique
at the moment). Only a change in the input parameter of ergo time (or
race time) makes a difference to the prognostic time predicted
(maintaining the wind constant). For each person there is a single
prognostic speed, but there are unlimited combinations of outboard/
rate to achieve this.
So we can make the gearing lighter, but have to rate higher to
maintain the speed. Or we can make the gearing harder, but have to
drop the rating to ensure we can complete the race without blowing up.
I think some of the subtlety of rigging is cordinating the speed of
action to the physiology of the rower. A lighter gearing means a
faster speed of action (quicker drive) (and vice-versa) which may or
may not be best suited to the rower. Some of this speed of action can
be 'learnt' as in getting used to the speed, otherwise it is largely
dependant on the physiology (muscle composition...).
I'm currently thinking on the basis that actually the gross difference
in speed is based on how fit and strong we are, and that rigging can
be tailored to hone small differences.
Carl Douglas
It is clear that being fit & strong is a pre-requisite for performance,
but I am sure it is not the only requirement. To understand that one
need only compare the recent performance of the winning HW Men's 2- in
Lucerne with that of the rest of the field. It is, IMHO, clear that the
New Zealanders are moving their boat more efficiently than the others to
have stamped out & maintained that huge early lead, as it is most
improbable that they have a >10% higher power to weight ratio than all
of their opponents.
It is also implausible, I would suggest, that their speed advantage came
for how they were rigged.
Scullers are prone to the snares & delusions of riggery-pokery. After a
dull outing when nothing seems to go too well you have a fiddle with the
rigging. Next outing seems better, so you think you've worked magic
through that rigging change. Later the shine goes off the sculling, so
out come pitch gauge & spanners for another fiddle. And so on.
For those caught by this it can become a circular process, constantly
seeking perfection from the rigging by a random walk of changes &
eventually revisiting all previous rig set-ups. I've seen it in done &
it can be really unhelpful.
It is quite normal to have a downer for a few outings through no fault
of rower or boat. Psychology, external stress, even the desire to see
some change, can delude us into thinking that somewhere lies an ideal
rig which will permanently transform our rowing. We can even take
ourselves into a fringe areas where indeed nothing will work. Call it
the curse of having really good riggers & pitching systems ;)
When you make one of these adjustments you may be stimulated by the
experiment, invest confidence in the outcome then have a good outing.
That tells you, wrongly, that you really do know how to improve your rig
& that changes you make will be "a good thing" per se. You put a
little bit extra into the next few outings, confirming that you got it
right. But you accumulate additional fatigue from those special days -
because you're now working harder under the stimulus of self-belief, or
for some unrelated reason. Your performance, or the feel of your
performance, then starts to slide. At which point, uncertainty
intrudes. Maybe, you think, I need to make another change? At which
point you are well on the way to becoming a rigging addict.
Don't get me wrong: rigging really does matter. I think it crazy to
have riggers you can only pitch with the help (?) of a scaffold pole, &
I regret the general incomprehension of the simpler aspects of pitching
(no, those eccentric inserts in the oarlock do not compensate for errors
in pin pitch). And I think if important that riggers be stiff, & not
keep self-adjusting as clunky welds stress-relieve themselves over time.
The solution to all of that is a matter of education, good engineering
& design - no, riggers don't have to change shape with age & use!
We need to understand that the most adaptable, adjustable & fallible
part of the rigging & gearing of your rowing is us, the rowers. Given
time, proper motivation & a relaxed perspective, a good rower can make a
fair success of any half-reasonable rig. But you have to accept that
you will always get more out of working out how to get the best out of a
given reasonable combination of span, height, inboard & overall oar
length through varying your own stroke length, blade depth &
catch/finish angles &, most of all, how you actually use the oars (speed
of catch, relaxation of finish, loading profile, feathering technique,
recovery rhythm & so on ad infinitum).
Rigging measurements have become an obsession, a shining path to better
results, but that is a delusion. FISA publishes the rig data for top
competitors &, for some peculiar reason, average rowers then think these
numbers must have some kind of deep relevance for them too. The way to
success is to concentrate on how you row, to accept that if it went well
yesterday or last week it has the potential to go well next week without
any change in rig - that the thing which is fluctuating most & spoiling
your outing might just possibly be you.
Steven M-M
Charles & Tink,
One of the reason I don't fuss much with my rigging is my primary
focus is not load or gearing. I think of rigging as more like getting
a bike fitted to my body dimensions and gearing/load more the
combination of stroke rate and power application.
Steven M-M
Tink
>
> - Show quoted text -
I am quite a keen cyclist and I quite like the analogy to a bike, but
I see the analogy to a single speed bike.
I'm a regular reader of a cycle forum. One of the first things always
mentioned when someone discusses bike size is to get a bike fit.
I had one at a local bike shop. They take various measurements of
your body (leg length, shoulder width, arm length, torso length...)
and put it into a computer. This outputs not only standard frame
size, but also frame geometry (incase you wanted a custom built frame)
and rider position (stem length, crank length, headset height, seat
height, horizontal seat position...).
If you ask a (competitive) cyclist, then this bike fitting is
crucial. So if rigging is like a bike fit, then it is important if
you are after getting the most speed out of your rowing. If you are a
recreational cyclist then the fit is not so crucial, a more basic fit
will do. But then of course if you are a recreational rower the
rigging is also less important.
A single speed bike is what is says, a bike with only a single gear.
No chance to change during a ride, you pick you gear and stick with
it. Too big a rear gear and you'll struggle on anything but flat, too
small a gear and on the flat you'll legs will be spinning too fast for
you to be able to add to the bike speed.
I see picking the right size frame as getting the right size boat (the
gross set up).
I then see the finer set up of rider position as the inboard rigging
(span, inboard, stretcher position...) (the finer set up).
I see the choice of single speed gear the same as chosing the oar
outboard (the gross gearing).
In both cycling (and rowing) the load can be varied by cadence (rate)
and power application (the finer gearing).
------------------------------------
The bike fit is much more scientific than any boat rigging set up I
have seen. Once fitted on the bike, you may need some minor tweaking
but the gross set up is there. Rigging seems to be much more hit and
miss based on how we feel, or copying of international rowers, or
using whatever the last person left it as.
I often wonder why we don't have something similar to the bike fit in
rowing?
I like the Kleshnev rigging calculator as it tries to give us a more
scientific mechanism for rigging set up. At the moment it bases
inboard on height, which is like basing the bike fit on height (rather
than the specific lengths of leg, torso and arms), but is much better
than assuming one size fits all.
I should add that in the bike fit they have a number of different
riding positions based on the type of cycling you'll be doing (time
trials, sportive, recreational...). I should also add that the bike
fit description is based on my experience, and although similar at
other bike shops might not be exactly the same.
Tinus
I like this comparison. I must add that the third comparison, choosing
the gear, may be more complicated in rowing. By changing the outboard
one does not just change the gearing but also the hydrodynamics. So,
one could choose to sacrifice an optimal geometric setting in order to
improve the blade hydrodynamics.
Also, the geometric setting may have effect on various hydrodynamic
issues as boats speed variation during the stroke cycle associated
with larger stroke length and lower stroke rate and boat pitch
variation associated with the same and with stretcher and handle
height as well.
Maybe it are these complications which have made rigging more like an
art than science. Also the fact that in rowing people are working in a
crew makes the variation in settings difficult and rowers are more
used to adapt to the setting. Another important reason, less money is
involved in rowing.
Walter Martindale
splitting hairs here, but wouldn't the 'optimal geometric setting' be
one that enhances blade hydrodynamics?
The big thing, as you mention, is that the rowing world cup ain't the
Tour de France or F1... ($$$$$$$$) the steering wheel in an F1-type
car is more than $40,000NZ according to one of the sponsors of the NZ
team...
W
Tinus
Or the optimal geometric setting would be one that enhances the rower
ability to apply power. The rigging both has an effect on the ability
of the rower to apply power and the effectiveness of the mechanism to
transfer the power. It is most likely that they are not both optimal
for the same rig.
E.g. a trend may be to decrease the oar length (with shorter stroke
length) which allows the rowers to apply more power (this is the
Kleshnev rigging model which decreases the oar lenght to adept to the
optimal handle speed). However it is associated with higher stroke
rates and higher blade forces/velocity and it results in more shell
drag and blade slip. So in this case optimizing the geometric setting
to benefit the rower geometry and physiology (as is so easily done in
cycling) may have a negative effect on optimal power transmission.
Tinus
To clarify a bit more. With geometric setting I was targeting Tink's
first two points in the rowing-cycling comparison. Choosing the frame
and rider position. The adjustment of the rigging to adjust to the
rower. My claim is that this is not always good in rowing because you
also need to adjust to the water and not the rower only.
Carl Douglas
Yes.
The best performance of a complex system is normally the outcome of the
locally sub-optimal performances of its different components. Chasing
the optimum in any one component without regard for the rest of the
system may prevent attainment of acceptable performance levels by the
others and the whole.
In short, everything is & must be a compromise.
The successful athlete rarely understands this but is blessed with
exceptional physical attributes & the good luck to make the right sort
of compromises.
Charles Carroll
> the locally sub-optimal performances of its different components.
> Chasing the optimum in any one component without regard for the rest
> of the system may prevent attainment of acceptable performance
> levels by the others and the whole.
>
> In short, everything is & must be a compromise.
>
Carl,
Wonderfully said!
It makes me wonder if you have offered another rowing truth? Or could
this be another case of great minds thinking alike?
"All of it-center of gravity, shell length, beam, depth, surface drag,
wave drag-is a matter of compromise. Gain speed here; give it away
there." -Graeme King
Warmest regards,
Charles
Zbigniew A.
Moreover, this compromise may look differently for different people.
What is *optimal* for one rower, may be not necessarily best for the
other, *his* optimum might be different.
--
Yours Virtually, Zibi
Tinus
I believe that the compromise is mostly dictated by the boat mechanics
and much less importantly by personal preferences. Maybe a centimetre
more or less or some stretcher settings but that's about it.
The argument for this thought is heuristic. A large variation in
stroke rhythm, frequency and length can be found between different
boat types. If some personal preference for these parameters is
important then there would already have been a much wider standard of
different settings around without a need for scientific help.
Walter Martindale
I've usually understood "optimal" to imply getting everything just
right for the individual case. e.g., in the 70s (I wish I could cite
the study but we only saw a 16 mm film during the biomechanics
class...) a study was done in South Africa to find the 'optimal' way
to kick a target at waist height. The researchers considered inertial
characteristics of the thigh, lower leg, foot, the muscle contraction
rates of the muscles involved, and the neural transmission rates IIRC,
and computed an optimal movement pattern for a person to kick a target
that was waist high. The subjects had to be tethered in place and
could only use the one leg (which had to be weighted to slow it down
enough to be measured using the equipment of the day) and they found
that the subjects could be trained to do the optimal kick.
Computing power back then wasn't what it is today, but (and here's
where my memory is very hazy) they said something about 24 hours of
computing on a PDP something or another, with 30 or so variables and
nearly 30 ordinary differential equations.
For a kick.
in two dimensions.
So optimising rowing movement, accounting for neural transmission
rates, muscle contraction rates, segment inertial characteristics, for
both legs, torso, both arms, and so on, in three dimensions is not
trivial, and then you have to add in equipment. I rather doubt anyone
has done it - there's not the money in it that there is in optimising
fighter pilot seating positions or F1 seating positions (or, for that
matter, tour de france seating positions)
so we "eyeball" and make a lot of compromises.
Tinus
You often see in computer simulations that small cases may be done
well but once increasing the amount of variables the system becomes
intractable. This kicking example is a highly isolated situation. With
every extra body part additional free variables are added. Maybe a
computer may still solve it but the outcome will not bear a physical
explanation anymore.
An example is the Phd research by Coppel. She has made a lot cfd
calculations on the blade water interactions. But when she has to put
it into the entire framework of a boat rower simulation she has a
problem because she only knows values for 9 different blade angles and
also these values are static solutions. So she has to make an
approach. Another problem is that the solutions don't take into
account the free surface of the water-air boundary which plays an
important role in blade resistance as well.
I've always thought that the best solution to rowing computer
modelling would be some semi experimental computer simulation in which
a lot system boundaries to the computer model are given by
experimental data. In such a case the current obstruction would be a
lack of experimental data to be put in.
Walter Martindale
>
>
> You often see in computer simulations that small cases may be done
> well but once increasing the amount of variables the system becomes
> intractable. This kicking example is a highly isolated situation. With
> every extra body part additional free variables are added. Maybe a
> computer may still solve it but the outcome will not bear a physical
> explanation anymore.
>
> An example is the Phd research by Coppel. She has made a lot cfd
> calculations on the blade water interactions. But when she has to put
> it into the entire framework of a boat rower simulation she has a
> problem because she only knows values for 9 different blade angles and
> also these values are static solutions. So she has to make an
> approach. Another problem is that the solutions don't take into
> account the free surface of the water-air boundary which plays an
> important role in blade resistance as well.
>
> I've always thought that the best solution to rowing computer
> modelling would be some semi experimental computer simulation in which
> a lot system boundaries to the computer model are given by
> experimental data. In such a case the current obstruction would be a
> lack of experimental data to be put in.
Of course - I think I implied that the kick study was an isolated
single movement and that there are a huge number of variables to
consider going to the whole body in a complex/simple movement like the
rowing/sculling stroke.
I haven't been following the research but I understand that early
attempts at 'optimising' walking via computer was pretty good for one
stride but after about 4 or 5 strides the model computed sufficient
forces to rip a real person apart.
I think as you remark about lack of experimental data, the rowing
biomechanics world is still in the "descriptive study" stage. - here's
what we find is going on but we don't know about this, that, or the
other....
W
Zbigniew A.
>
> Of course - I think I implied that the kick study was an isolated
> single movement and that there are a huge number of variables to
> consider going to the whole body in a complex/simple movement like the
> rowing/sculling stroke.
>
In a years i was not rowing, i was involved in bicycling, partly at the
competitive level (mtb marathons). I was always attracted to "all the
theory behind it".
I remember reading about a scientist from a famous univeristy,
unfortunately don't remember which one (MIT?), who decided to write
mathematical model of a bicycle ride. After about a year, when his
algorithm consisted of over one hundred equations, he realized how far
he is from the goal and gave up.
I like Tink's paralell with a bicycle fit. Especially, the comparison to
finding a right gearing on a single speed bike!
When bicycling, once i discovered the difference a crank arm length
makes. Totally by accident: i had two different crank arms, from two
different sets fitted. And when riding, i discovered how different is a
working of my left and right leg, then it took my a long time to find
out that the crank arms are different in length. And when i wanted to
explore this topic, i discovered a "veil of mystery". Several theories,
partly contradictory. Most often one would hear: don't mess with it, use
the same what everyone else uses. Once i found a "scientific calculator"
which recommended me crank arm length 210 mm, what is absurd. BTW, "the
golden standard" is 170mm for road racers and 175 mm for mtb; by trial
and error i found out that 180mm works for me very well in most situations.
In rowing a similar story is with span/spread. Some say spread does not
influence gearing (of the oar) -- and they are right. Others say (or
repeat one after another) one centimeter of span makes as much
difference as three centimeters of oar length -- and they are right, in
a way, too. Most people just go for what everyone else uses. :-)
--
Yours Virtually, Zibi
Carl Douglas
It would be so easy to say "It's all too complex so let's carry on
guessing", but that is weak, defeatist & give control back to the
believers in coaching ju-ju. Man is a most complicated machine & rowing
is an activity which, while superficially simple, is deeply intricate to
analyse (& deeply misunderstood by most practitioners.
If you can, study this 2- race which starts at about 0:4:50 in:
http://www.bbc.co.uk/iplayer/episode/b012lrfj/Rowing_World_Cup_2011_Lucerne_Highlights/
and may be available from other sources too.
In the middle 1000m the Kiwis generated ~15% more actually _useful_
(i.e. propulsive) power than anyone else, which is what it takes to gain
that margin over the rest of the field in that distance. I very much
doubt that they worked 15% harder than their opponents - which would be
an incredible extra input. I don't believe they'll have had any
meaningfully different rig.
I'd welcome all views on what we see in that dominant Kiwi performance
which simply killed the opposition.
FWIW, here's some of what I see, although there is also much wich cannot
be seen due to the camera angles & regrettable fixation on the crew to
the near exclusion of the blades:
1. Great smoothness (especially from stroke)- recovery in 1 piece,
stroke in 1 piece, with no checks, accelerations or funny actions in any
part of the bigger action
2. Great length (like other recent dominant antipodean 2- crews)
3. Almost horizontal hand action from extraction to catch
4. Feathered extractions
5. Instantaneous catches - the recovery immediately becomes the catch
6. No backsplash - there's an entry splash but it goes astern
7. Very little bow pitching compared with some of the others
It looks so easy, although doubtless the product of good training &
great skill. The 2 rowers' actions aren't identical but the outcome is
almost magical. They look like scullers.
Will any of the other crews in that final stop & study for long enough
to learn how to improve what they do or will they, as so often in the
past, kid themselves that they can go faster by doing more of the same
as before?
Walter Martindale
> URLs: www.carldouglas.co.uk(boats) &www.aerowing.co.uk(riggers)
The thing to do is not to imitate but to see what it is that's making
them fast - is it blade/seat timing? Recovery dynamics? Fitness?
Length in the water? All of the above? Coaching? Hard Yards? The
technical model held in the coach's head and relayed to the crews?
All of the above?
If what one sees them doing is different from the technical model that
is held dear (by whomever), should he or she re-examine the model in
light of the movements of those who are winning? (I do, frequently,
and I try to keep my technical model 'evidence based' which I think
sometimes puts me at odds with some coaches)
W
Charles Carroll
I have been reading and sometimes attempting to contribute to these
discussions on gearing for years now. I have even started a few
myself. The only conclusion I have been able to reach is that the
number of variables in any given equation has so far made it all but
impossible to formulate an unvarying and immutable scientific law upon
which the facts depend.
Consider at all the variables that correlate with gearing: boat speed,
oar angle, blade shape, outboard, inboard, water conditions, air
temperature, wind speed, rower's height, rower's weight, ratio of
torso to legs, arm length, upper body strength, lower body strength,
shell length, shell width, shell rigging, shell weight, et cetera. Fit
them all into an equation, then add rower's physiology and where the
rower is in his or her training. And I suspect that even with all
these variables I am still missing a few.
This is not an argument for giving up trying to understand and improve
gearing and biomechanics, etc., in order to row better and move boats
faster. Instead think of it merely as a warning against mistaking
simple possibility for reliable scientific law.
I like your proposal that in generating 15% more useful power than the
competition, a crew did not actually work 15% harder. The example you
offer is simple, it is straightforward, it is something anyone who
rows will understand, and it illustrates a vital correlation between
raw power and technical skill.
Consider the following passage from Peter Mallory's "The Sport of
Rowing." The passage comes from Chapter "155: Mike Teti Begins a
Journey." I think it provides strong reaffirmation of your premise -
namely, you cannot replace useful power with harder work.
Cordially,
Charles
_____________________
Easy Speed
Bob Kaehler, 2seat in 1998 and 1999: "Sometimes you just have a unique
combination. I think that the '98 '99 boat was just one of those boats
that had perfect blending. We were in control. We could do what we
wanted when we wanted to. We never lost a race.
"It's not that often that you get control in boats where it's relaxed
and easy. You have tremendous power, but it's just easy. It's not
hard. There's no effort. You're cruising along. In previous times
[1996], it was more like hammer, hammer, hammer . . . hammer as hard
as you could, and that was the training mentality during that period.
Hammer and survive. The next period was much smoother application of
power."
The technique at the beginning of the Teti Era was quite similar to
the "easy speed" approach of the 1994 World Champion U.S. crew under
Mike Spracklen described by Fred Honebein. Behind Princeton grad Chris
Ahrens, the post Spracklen champion Teti boats rowed Classical
Technique with a very strong emphasis of acceleration all the way to
the finish.
Legs coordinated well with the backs and together they provided the
source of effective smooth "Schubschlag" acceleration.
Chris Ahrens in 2000: "The past couple of years when I've been
stroking the boat, I can initiate things, but then when you feel these
seven guys behind you kick in, in some ways they just take over . . .
and there's a sense because everybody's hitting it exactly together
that you're kind of taken with the group."
Jeff Klepacki, 6seat in 1998 and 1999: "We had such a unique dynamic
in the eight in those years."
Ed Hewitt of www.row2k.com: "Mike's best rowing crews were in the late
90s; all competence, no tricks, no fretting."
However, as 2000 approached, the parallels to the experience of the
Spracklen crews of four years earlier seemed to multiply. Knowing what
happened in Atlanta must have weighed on the minds of many.
Porter Collins, a member of both the 1996 and 2000 eights: "I'm going
to show my true character when it comes down to the Olympic final. I'm
not going to let it slip through my hands twice! It's something that's
not going to happen!"
More athletes with bigger erg scores arrived in the year leading up to
2000. Pressure built. Tension increased.
Everything was about the Olympics. The extensive films taken in
practice in the months prior to the Olympics suggest that before most
practices, in fact before most competitive pieces in practice, the
coach reminded the oarsmen exactly what was at stake.
Mike Teti: "You're racing for a spot on the [bleeping] Olympic Team .
. . and the crew that's gonna make [bleeping] history."
And the athletes were listening and responding to the obvious
pressure.
Bryan Volpenhein, two-time World Champion by 2000: "An eight is all
about who has the biggest [assets], who's the toughest, and who can
make the eight go the fastest."
Mike Wherley: "[An eight] is different than most of the other boats
because it's almost reckless in a way. It's the only boat where you
can just haul on it."
Or can you?
___________________
2000 Technique
As it had twenty-four years earlier in 1976, and as it just had four
years earlier in 1996, the rowing technique changed gradually but
materially as the Olympics approached. Force application in particular
became indeed "almost reckless," and the magic, the "easy speed"
appeared to disintegrate.
Films convincingly show that it was a group mentality. No single
individual or coach was responsible for the change. Nevertheless, it
is useful to examine the rowing technique of stroke seat Chris Ahrens,
for he had embodied all that was extraordinary in the pre-2000 eights.
Films also show that the change involved the legs at the entry.
Instead of complementing the concurrent back swing as they had in
earlier years, by 2000 the legs dominated the backs. They completely
dominated the first part of the pull through, replacing hybrid
concurrency with overlapping sequentiality, even pure sequentiality,
replacing Classical Technique with Modern Orthodoxy.
In 2000, the legs were driven nearly flat by the time the oar shafts
were perpendicular to the direction of the boat instead of at the 90%
point in the pull through of just a year earlier. This was a huge
difference, equal in magnitude to the very same change in Spracklen
eight from 1995 to '96.
An increasingly dominating leg drive signals devolution from smooth
force "Schubschlag" to segmented force "Kernschlag". This was yet
another tragic example of Rowing History's Greatest Lesson, which has
been repeated over and over since the very beginnings of our sport.
As it was happening, Porter Collins understood well and tried to
explain the problem to his coach, Mike Teti: "It's not like shoom!
[demonstrating a smooth "Schubschlag" pull through with his hand] It's
like ugggh! . . . and then come through."
Pop and go.
Segmented force application became so ingrained into the team ethos in
2000 that it was even embodied in the coxswains' exhortations during
seat racing that spring.
Pete Cipollone: "Lock . . [pause] . . Send! Lock . . [pause] . . Send!
[This two-part refrain was called in cadence with his boat's two-part
pull through.]
"Front end! Front end!
"Everybody sit up and Catch!
"Lock . . [pause] . . Send!
"Lock . . [pause] . . Send!"
Seth Bauer, four times U.S. Men's Eight Coxswain between 1981 and
1988: "I actually introduced that call to the U.S. Team. Kris
Korzeniowski specifically taught me to say that in the 1980s. The
intent was to get rhythm into the drive. American crews tended to
believe that you just pulled as hard as you could on the drive, and
then rhythm happened on the recovery. Korzeniowski flipped that
around. He basically said, "Don't worry about the recovery. Get the
rhythm on the drive."
The unintended result in 2000, however, was rowing in concrete,
enormous energy expended without commensurate reward.
By the time the final 2000 boat was picked just weeks before the
Olympics in Sydney, it was obvious to all that there were very serious
problems.
Teti during a practice: "Something's not right. There's something that
I can't see.
"You shouldn't have to put that much effort into rowing steady state
and moving the boat."
Dan Lyons: "Teti was a ball peen hammer. When I rowed, that's what he
was. He was a hammer. A hundred seventy-eight pounds of hammer. And he
taught his crews to row that way.
"He had some great athletes. He had a good system which in the end did
not serve the country well long term."
Kaehler: "Towards the end, there were a couple of guys out, and we did
some seat racing. We were rowing some fast times with these
substitutions, and there was a point when I said, 'This is the boat!'
"It ended up not being the boat, but it would have won the Olympics.
Coaches are not going to go on one day's performance, but when you're
inside the boat, you feel what it's like and you know. You can sense
it.
"I believe that sometimes coaches should rely on their top athletes to
make assessments from the inside, not just what you're seeing visually
from the outside, because boat chemistry is an intangible.
"And when you change that . . . when you plug guys in that have huge
ergs . . .
"Fifteen seconds on an erg seems like this huge amount . . . but in an
eight it could mean nothing! When you get to big boats, one guy doesn't
mean a lot. You can put in a guy with a 5:50 or a 6:10, but if you've
got the other seven guys, and they're all rowing together, it's not
going to make a difference.
"Technique is what wins. When you have good power behind technique,
that's the whole package.
"The '99 Eight was a dominating boat power wise and technique wise,
and it was really technique based on our power. That was just the way
it was."
Ahrens: "We trained harder in 2000. All of our erg scores were better,
but I think what you do have is that we had a situation where it was
clear early in the summer that things were not going great.
"I think that the reason this pattern happens in the eight more than
in other boats is that everybody's thinking, 'Okay, what should I do
to make it better,' and there's not much you can do.
"I think that the eight in many ways is like herding cats in the sense
that you've got to have all these people focused in one direction,
thinking the same thing, and so when things aren't going well, no one
wants to talk about the fact that they aren't going well. You get into
this mode of everybody's trying really hard, but all that effort is
sometimes going against each other.
"Another problem was the nature of the selection process that was
imposed on us because of the fact that the four and pair had not
qualified for the Olympics the year before. That meant that by the
time it got down to selection for the Eight, there was no flexibility
for Mike to try different lineups, try different stuff."
Klepacki: "We had some phenomenal physical athletes come out of the
woodwork that spring, like Dave Simon, who was a physical specimen.
The guy had to be in like the top 1% of the world as far as physical
attributes and ability on the erg were concerned.
"There was so much power and juice in that boat with Dave Simon! We
rowed something like a 5:32 in flat conditions at a 32. It was
phenomenal! Oh my God!
"The problem was you're not going to win the Olympic Games rowing 32.
So when we got to race cadence at 36 and 38, it was a different
outcome.
"So the dynamic got mixed up . . . and then we were on the plane to
Australia."
Ahrens: "In 2000, I think we had a lot of bad luck. We got down to
Australia, and our oars hadn't made it, so we had to row with
different oars. And we couldn't row on a timed course. One thing after
another. Sometimes there's not much you can do about it."
Klepacki: "Musical chairs over in Sydney. Mike wanted to move me from
6-seat to stroke after the reps and put Chris in 6.
"I said to him, 'Mike you're grasping at straws. If you want to make a
move, go pull Wherley from the Four and put him in the Eight.'
"Obviously, we couldn't do that unless there was a medical reason, so
our hands were tied."
Ahrens: "The rep in 2000, I think that was the hardest race I ever
rowed in my entire life. It was us and the Romanians battling to win
the rep, and we ended up beating them by, I don't know, two or three
inches? But that in some ways was the performance that I felt was the
most courageous of that crew in the sense that we knew that it was all
about effort and pride."
Klepacki: "I think we won the repęchage by a bow ball over the
Romanians. It was the hardest I've ever pulled in my life, and we went
into the final wishing and hoping for the best, knowing that we were a
crew that was completely capable of dominating the field and winning a
Gold Medal. I rowed stroke, and we finished fifth."
Ahrens: "I'm not ashamed of our result. It was disappointing
personally, but at the same time I think that everybody in that boat
put forward a huge effort, and I think that crew had the quality of
people as people in terms of racing, aggressiveness, competitiveness,
toughness. I think the standard was very high.
"You had guys who mentally were just incredibly tough and incredibly
good at racing, Bob Kaehler, Porter Collins, Tom Welsh, everybody in
that boat.
"Tom Welsh would go through walls before he was going to stop. Same
thing with all those guys. That aggressiveness came through in the
style of racing that we had, and I knew that in a tough, tight battle,
that crew would win."
__________________
National Team Disease
But having the best athletes of a country come together for four years
to prepare for a single race, the Olympic final in the men's eights,
having them find success in the intermediate years and then failing in
the one race that counted was becoming a painful recurring pattern,
and not just in the U.S.
Ratzeburg in 1964 and 1972, GDR in 1972, New Zealand in 1968 and 1984,
Germany in 1992, the U.S. in 1976, 1988, 1996, and now 2000. Soon the
Canadians in 2004 would be added to the list.
Kaehler: "In three Olympics [1992 in the quad, 1996 and 2000 in the
eight], it happened to me all three times! The crews that I rowed in
the year before were much better crews than the ones that ended up
going to the Olympics, and the replacements were solely based on
ergometer scores. Period. Nothing to do with technique! Just power,
and in a lot of cases, the guys who have the most power are not good
boat movers.
"Power ego" is what it really comes down to. You're taking guys out
that don't have ergs and putting guys in that have huge ergs, and
performance goes backwards!
"Coaches can't help themselves. They do that."
Olympic letdowns have not been confined just to Olympic men's eights.
The U.S. women's eights in 1996 and 2000, both Canadian single
scullers in 1996 and the Canadian women's pair in 2004 also come
immediately to mind.
Over the last 200 years, the pattern is well established. A team that
begins with newness and freshness and easy speed rowing "Schubschlag"
gradually turns to segmented force "Kernschlag" when the training
intensifies and the pressure mounts. . . . and their world soon
implodes.
A human tragedy the first time. And the second. And the third.
But after decades? A century?
Why haven't we learned?
atkin...@gmail.com
> Dear all,
>
> I have had a lot of conversation lately with scullers who are rigging
> with reduced inboards. Instead of the standard formula, Spread/2 + 8
> cm, they are advocating using a Spread/2 + 6 cm.
>
> What is gained by shortening the inboard?
>
> An oar is a lever, and when you apply a force to one end of a lever,
> you exert a torque, which is defined as the product of two quantities:
> the length of the arm you're pushing on and the amount of force you're
> applying.
>
> So, doesn't the length of the inboard determine the torque? In other
> words, by shortening the inboard you reduce torque - this same torque
> that acts on the far end of the lever (i.e. the blade).
>
> Now why would any sculler or rower want to reduce torque anymore than
> is absolutely necessary? Wouldn't this be equivalent to saying that
> you want to row with less power?
>
> Warmest regards,
>
> Charles
Pursuant to shortening the inboard I have recently completed some new output from the computer model ROWING.
<http://www.atkinsopht.com/row/>
It seems to show that for any rower there may be an optimum oar lever ratio--toward inboards shortened from the conventional--but, I admit, the result doesn't shed much light on how actually to seek out such an optimum in the field.
If it's real and really "out there" I would hope that there might be some interesting way of tapping in to it.
Best regards to all,
Bill
p.s. Do not miss Carl's excellent post of 7/13/11 under this rubric.
Jim Dwyer
comfortable to row. That includes adjusting the gate height and footstops
height, rake and angle.
has proper catch and finish angles
trims the boat properly
has a gearing so you can maintain your personal race rate.
Your gearing should be adjusted for conditions such as headwind, tailwind
and the length of the race you are rowing.
You need to try different setting to see what works best for you.
Keeping notes helps as well.
After 50 years of rowing I have found a range of numbers that works for me.
Jim
"Charles Carroll" wrote in message news:97rt5f...@mid.individual.net...
I. M. Rowin
<Your gearing should be adjusted for conditions such as headwind, tailwind
and the length of the race you are rowing.>
especially sprint vs head vs long distance (marathon) races?
I. M.
thomas....@googlemail.com
atkin...@gmail.com
> Sorry, I'm not sure if its just me but I can't access the model youve linked, sounds very interrstibg !
I agree, something is wrong with the link in my post.
Try leaving rec.sport.rowing and typing the link into your browser.
<http://www.atkinsopht.com>
Regards,
Bill
Jim Dwyer
be changed. I also carry CLAMS in case the conditions change and they
increase the inboard by 1 cm.
I am a lwt masters so I have very little power. I like to race against the
big guys in a tailwind or rough water or preferably both.
Basically I unload for a headwind and/or a longer race although if you want
to row a longer race at a lower rate you may want to stay with the same rig.
Experiment with different loads to determine the race rate that you want to
achieve for the length of the race.
I decrease my outboard by 2-4 cm to lighten the gearing.
If you decrease your outboard by a great deal you may have to lower your
height to compensate. For example if you go from a CII smoothie to a fat
blade scull.
Jim
"I. M. Rowin" wrote in message
news:Bd2dneq-Vqq2nh7L...@earthlink.com...
martin...@gmail.com
the arc length of the athlete is governed by theitr hight, leg length arm length flexibility etc but Kleshnev has given a formula to calculate this as
0.297865 * height + 108.387 (cm)
he also ststaed that this is an ideal and would adjust due to age e.g. master could be 90% of 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 inboard 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 of the hands in relation to the body at the finish. There is another body of work showing this when I can find it ) If we said an overlap of 16 then span would be (86*2)-16 = 156.
then its just a case of altering the length to suit you in terms of rate / fatigue etc.
valery....@googlemail.com
> Geometrically, a greater overlap (smaller span) will require the athlete to sit further towards the bow of the boat to achieve a constant position of the hands in relation to the body at the finish. There is another body of work showing this when I can find it ) If we said an overlap of 16 then span would be (86*2)-16 = 156.
except the last equation, which should be:
(86*2)-16 + (2cm*2) = 160
where 2cm is the half of oarlock width = distance from the oar button to the pin
Valery
William McRae
2. Inboard oar length is then selected based on allowing comfortable release at your comfortable layback.
3. Outboard oar length is then selected based on the gearing that best suits rowing style and level of fitness. Not too heavy, not too light. Basically what lets you go the fastest for 750 m and still have enough gas to pick it up a bit for another 250……