Sculling speed v. sweep-rowing speed
CraigC
"Why is a sculling boat faster than the comparable sweep boat (i.e.,
double vs. pair, quad vs. four, octuple vs. 8+)?"
He says, essentially, that the difference in speed is about the boat.
In sweep rowing, forces are asymmetrically distributed to the hull,
causing unproductive torque and side pressure. Sweep rowers and
scullers generate about the same amount of total force, but in sweep
rowing, more of that force is lost to the hull, so less force can be
translated into boat speed.
I say that the speed difference is about the inherent biomechanical
efficiency of sculling (applying muscular energy and body movement
symmetrically using two oars) versus sweep rowing (asymmetrical body
movement and application of muscle strength to a single, bigger oar).
Because sculling makes more efficient use of the athlete's strength
and body movement, scullers are able to apply more force to the
footstretchers, so the boat goes faster. Modern shell construction
methods and materials minimize any loss of energy from the system
arising from asymmetrical distribution of forces on the hull in sweep
rowing.
Who wins the bet?
mruscoe
> A buddy from my rowing club and I have a little wager on the question,
> "Why is a sculling boat faster than the comparable sweep boat (i.e.,
> double vs. pair, quad vs. four, octuple vs. 8+)?"
>
Bigger overall blade area with 2 sculling oars vs. 1 rowing oar.
Longer stroke arc (angle) in sculling.
Carl Douglas
You win, Craig.
It's not about side forces, either, since forces alone do no work & thus
do not represent lost energy. Nor is it about modern hull design or
construction - no measured or measurable amount of energy is dissipated
within the structure or the components, nor ever was.
The rowing stroke is just less efficient. The included angles of the
sweep stroke are smaller, which applies a distinct limitation on
performance. The off-axis forces within the body, arising from the
somewhat asymmetrical action, have very little against which to react,
so it is you who has to provide that reaction, generating forces &
movements which keep you in the boat but don't move it.
A plus for sculling comes from the generally greater skill &
watermanship of scullers. Sculler have had to learn individually what
moves a boat, whereas rowers are usually coached by a system which has
to concentrate on teaching disparate individuals to fit as a crew - a
process which eliminates the free learning process (& free failing
process) by which good scullers are self-selected.
How much was the wager?
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)
CraigC
> URLs: www.carldouglas.co.uk(boats) &www.aerowing.co.uk(riggers)
Hi Carl,
Too bad (for me) that the wager is only for a couple of rounds at a
local pub -- not for, say, a Carl Douglas 1x. I'll have to raise the
stakes next time, to make it more interesting. ;-)
Thanks,
Craig
CraigC
Carl, to continue the discussion a bit -- and believe me, I'm not
trying to argue in favor of my buddy's position in this wager -- but
I'm curious about what you said about forces alone doing no work, and
stiffer boats (thanks to modern materials and design) having nothing
to do with the equation. If there's an analogy to be made here with
bicycle frames, I know that stiffer frames mean that less of the force
applied to the pedals (reacting against the weight, seat, and hands of
the cyclist on the handlebars) is lost to frame flex. I'm not very
technically minded or knowledgeable about the laws of thermodynamics,
but I suppose that this frame flex must create some friction within
the framing members of the bike, so some muscle-generated energy is
dissipated as heat. So light, stiff bike frames are good in terms of
speed (hence the rise of carbon fiber, aircraft alloy, and titanium
frames), except that they create a very bumpy, uncomfortable ride, so
stiffness has to be balanced against other optimizing factors.
Isn't it the same, at least to some degree, in a rowing shell? I've
rowed in old 8s in which it felt like a great deal of our energy was
being absorbed (like a shock-absorber) by a floppy hull that had lost
its rigidity. So don't side forces or torque or flex play at least
some role in all this? Would the same old 8+, rigged as an octuple,
have the identical hull-flex issues, so this wouldn't play a part in
the speed difference between the performance of the 8+ and 8x rigging
of the same hull?
-Craig
Carl Douglas
You don't lose force through frame flex, but you do gain a degree of
confidence from a stiffer frame.
With a more flexible structure, some energy goes into deforming that
structure -
work done = sum from zero to maximum load of (force applied x
incremental deformation)
That stores energy in the structure, & most bike frames are efficient
springs, so they store energy in deformation without loss & they return
that energy also without loss. So, if your technique allows, all of
that stored energy is returned as you reduce the load as you transfer
from one leg to the other.
I don't know where the most flex occurs in a bike, or where this
storage/return process is least welcome or acceptable. Nor am I
particularly familiar with the urban myths that may tell cyclists what
matters even when perhaps it doesn't. I'd guess that handlebars would
be one area of concern, also the stiffness around the bottom bracket
under pedal loadings, flexure of the forks, deformation of wheels, twist
& flex in pedal cranks, chain elasticity, torsional wind-up in the rear
wheel (relative rotation between hub & rim), movement of the saddle.
But I lay no claim to cycling expertise!
In rowing, most of the energy storage & return within the hardware
occurs in flexing the oar, while the forces & consequent deformations in
the rest of the structure are relatively low. Also, the cadence/rating
is far lower than for cycling, so even at peak ratings the lags due to
energy storage/return may be much less important.
But there you have it. We are talking in rowing about a complex energy
storage/return system involving not just the elasticity of the
structural components but, most importantly, the inertial elements - the
relative motion of yourself, a heavy mass, & the much lighter boat,
under a low-rate cyclic loading leading to large boat-speed & hull drag
fluctuations through that cycle.
>
> Isn't it the same, at least to some degree, in a rowing shell? I've
> rowed in old 8s in which it felt like a great deal of our energy was
> being absorbed (like a shock-absorber) by a floppy hull that had lost
> its rigidity. So don't side forces or torque or flex play at least
> some role in all this? Would the same old 8+, rigged as an octuple,
> have the identical hull-flex issues, so this wouldn't play a part in
> the speed difference between the performance of the 8+ and 8x rigging
> of the same hull?
> -Craig
I'd thought we were trying to compare like with like! Now we're
comparing floppy old eights whose poorly made joints are opening up with
brand new kit. And then relating that to modern bikes. Strewth!
OK, if it really is a string bag, then the ability of each sculler to
keep their own bit level must help. But that's far away from your
original bet, isn't it? That said, some of us have had the dubious joy
of rowing antique eights & fours where it was too easy to have bow's &
stroke's riggers almost in the wate at the same time. We were told to
quit moaning & learn to row our riggers level.
Reckon I've earned my pint!
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
Cuddle Bunny
The original question that started this discussion/wager was my
question to our local rowers as to why octo's weren't more common than
eights being the fastest possible configuration without needing a
different/larger hull. I also suggested that a shell designed with
sufficient strength to support sweep rowing would be strong enough to
support sculling because of the reduced lateral stress from the
symmetrical forces applied by sculling rigging. I see several online
references agreeing with that statement and I have drawn diagrams of
the static internal forces in sweep and sculling rigging that convince
me of what seems obvious. :
http://www.spiritus-temporis.com/rowing-sport-/equipment.html
http://en.wikipedia.org/wiki/Rowing_%28sport%29
http://ndacrew.org/NDAequip.html
etc. etc.
I hope that is agreed before going on to the follow on questions that
arose from that start point
Why is sculling faster?
Is it primarily because the rower can apply more force or because that
force can more efficiently generate forward motion?
I see in summary of the responses to why sculling is faster so far:
1: Sweep rowers are better than scullers.
That doesn't seem to be a reasonable argument for why the consistent
results at peak performance where sculling race results are
significantly faster than sweep boats. Sculling boats are faster
across the board for lightweights and heavyweights, pairs/doubles and
fours/quads at highly competitive events including these lists of
world records and Olympic records:
http://en.wikipedia.org/wiki/List_of_world_records_in_rowing
http://www.btinternet.com/~rowing.biddulph/olytime.htm
I would expect that sweepers are as well prepared at the highest
levels of competition as scullers.
I suggest that is not a significant reason why the fastest times are
for sculling boats
2: Possibly the most significant issue is the approximately 1.5x
bigger overall blade area with 2 sculling oars vs. 1 sweep oar. That I
believe is one of the biggest factors in the performance difference.
The increased area and therefore reduced slip in the water is a major
factor.
Reference:
http://www.atkinsopht.com/row/bladarea.htm
Question: Have there been experiments using shorter outboard length
for sculling oars with much larger blade area? Seems like that could
even up the disparity.
3: Different angular range that oars travel through. I believe the
sweep oar having a shorter angular range should actually be more
efficient in in that respect the oar being more efficient in the mid
range closest to perpendicular to the hull. Sweep stroke rates are
slightly faster than sculling stroke rates because of that.
4: The head in the boat linear motion of the sculling rowers action
allows a greater average force to be applied to the oar. Peak force
applied I would assume is similar to sculling. But the average force
that can be applied is less due to the non linear body movement and
asymmetrical pull.
I think those 4 areas cover the differences.
If anybody has links they would like to share that help explain and
particularly visualize the issues involved I would appreciate it.
Thanks Martin
Kit
wrote:
> Wager/drinking/rowing buddy (Martin) here.
>
> The original question that started this discussion/wager was my
> question to our local rowers as to why octo's weren't more common than
> eights being the fastest possible configuration without needing a
> different/larger hull. I also suggested that a shell designed with
> sufficient strength to support sweep rowing would be strong enough to
> support sculling because of the reduced lateral stress from the
> symmetrical forces applied by sculling rigging. I see several online
> references agreeing with that statement and I have drawn diagrams of
> the static internal forces in sweep and sculling rigging that convince
> me of what seems obvious. :
>
2 points.
re #1 I didn't see that conclusion. In fact I saw the opposite. Did
you read it the wrong way round ?!
re #3 Midstroke (ie blade perpendicular to the boat) is regarded the
least effective part of the stroke, because, without hydrodynamic
lift, the blade is liable to drag through the water and so lose work
done by the rower against the pin (a bit like sprinting on soft sand).
At the front & back ends of the stroke, the blade is moving sideways
edge-first through the water, creating lift and supporting the spoon
in the water, making a much better fulcrum for the levers and
transferring more work to the pin.
Carl Douglas
> Wager/drinking/rowing buddy (Martin) here.
>
> The original question that started this discussion/wager was my
> question to our local rowers as to why octo's weren't more common than
> eights being the fastest possible configuration without needing a
> different/larger hull. I also suggested that a shell designed with
> sufficient strength to support sweep rowing would be strong enough to
> support sculling because of the reduced lateral stress from the
> symmetrical forces applied by sculling rigging. I see several online
> references agreeing with that statement and I have drawn diagrams of
> the static internal forces in sweep and sculling rigging that convince
> me of what seems obvious. :
>
> http://www.spiritus-temporis.com/rowing-sport-/equipment.html
Unfortunately, this statement, which I copy from the above reference, is
a load of armchair drivel:
"With the smaller boats, specialist versions of the shells for sculling
can be made lighter. The riggers in sculling apply the forces
symmetrically to each side of the boat, whereas in sweep oared racing
these forces are staggered alternately along the boat. The sweep oared
boat has to be stiffer to handle these unmatched forces, so consequently
requires more bracing and is usually heavier - a pair (2-) is usually a
more robust boat than a double scull (2x) for example, and being heavier
is also slower when used as a double scull. In theory this could also
apply to the 4x and 8x, but most rowing clubs cannot afford to have a
dedicated large hull which might be rarely used and instead generally
opt for versatility in their fleet by using stronger shells which can be
rigged for either sweep rowing or sculling. The symmetrical forces also
make sculling more efficient than rowing: the double scull is faster
than the coxless pair, and the quadruple scull is faster than the
coxless four."
In the real world there are no differences, actual or necessary, in the
weights of sweep & sculling boats. And boat weight has no measurable
effect on boat speed within the range of boat weights commonly in use.
> http://en.wikipedia.org/wiki/Rowing_%28sport%29
This following statement from the Wikipedia article sets the tone:
"The boats are propelled by the reaction forces on the oar blades as
they are pushed against the water". That opening statement displays a
most fundamental misunderstanding of fluid dynamics.
> http://ndacrew.org/NDAequip.html
Beware the cross-referential tendencies of different websites - A copies
from B copies from C, so a multiplicity of similar statements arises
which convince the investigator that "this must be true". Thus in the
above we read:
"Originally made from wood, shells are now almost always made from a
composite material (usually carbon-fibre reinforced plastic) for
strength and weight advantages. FISA rules specify minimum weights for
each class of boat so that no individual will gain a great advantage
from the use of expensive materials or technology."
First, that statement is plain wrong, & secondly it is self
contradictory. Either there are weight limits (easily met by
well-designed & built wood composite shells, BTW) or there are no weight
limits. Beware presuming the supposedly obvious.
> etc. etc.
>
> I hope that is agreed before going on to the follow on questions that
> arose from that start point
So there is no possible agreement. Sorry that the facts don't fit with
popular fiction, but I deal in facts.
>
> Why is sculling faster?
> Is it primarily because the rower can apply more force or because that
> force can more efficiently generate forward motion?
Probably both.
>
> I see in summary of the responses to why sculling is faster so far:
>
> 1: Sweep rowers are better than scullers.
I think you intended the opposite to that statement?
>
> That doesn't seem to be a reasonable argument for why the consistent
> results at peak performance where sculling race results are
> significantly faster than sweep boats. Sculling boats are faster
> across the board for lightweights and heavyweights, pairs/doubles and
> fours/quads at highly competitive events including these lists of
> world records and Olympic records:
>
> http://en.wikipedia.org/wiki/List_of_world_records_in_rowing
> http://www.btinternet.com/~rowing.biddulph/olytime.htm
>
> I would expect that sweepers are as well prepared at the highest
> levels of competition as scullers.
What you might expect looks to me like an attempt at wish fulfilment.
In a supposedly technical discussion we should rely only on demonstrable
fact.
I've already explained the fundamental difference in learning approach
between scull & sweep - in sweep you must drill rowers in ways that get
th4em together, since if not rowing the same they'll be slower than
otherwise, whereas scullers self-select by learning through trial &
error what actually moves boats.
Next, it is pretty well accepted (but I'm of course open to challenge)
that good scullers make outstanding sweep crews, but not vice-versa.
>
> I suggest that is not a significant reason why the fastest times are
> for sculling boats
>
> 2: Possibly the most significant issue is the approximately 1.5x
> bigger overall blade area with 2 sculling oars vs. 1 sweep oar. That I
> believe is one of the biggest factors in the performance difference.
> The increased area and therefore reduced slip in the water is a major
> factor.
>
> Reference:
>
> http://www.atkinsopht.com/row/bladarea.htm
Since Bill Atkinson denies the importance of fluid dynamics in blade
action, I'm not about to agree there.
Your statement is tantamount to saying that bigger wings would make a
plane fly more economically, which overlooks the tendency for there to
be optima - a right size for a wing or any foil (including an oarblade).
Next, you imply that oars are wrongly sized & should be bigger, or
conversely might argue that scull blades should be smaller. In fact I
see scant evidence that blades are ever sized according to the power or
strength of the user. Lightweight women seem to use surprisingly
similar blade areas to heavy men, & how can that be right?
It might be a good start to appreciate that understanding of the
propulsion of rowing shells labours under a large science deficit.
>
> Question: Have there been experiments using shorter outboard length
> for sculling oars with much larger blade area? Seems like that could
> even up the disparity.
Individuals do experiment, but maybe not as widely as we might wish.
What seems to be missing is any acceptance that different sizes,
gearings & rate are likely to demand different techniques. For as long
as rowers continue to believe there is a perfect style or rhythm, we
shall keep forcing ourselves back into an unnecessarily constraining box.
>
> 3: Different angular range that oars travel through. I believe the
> sweep oar having a shorter angular range should actually be more
> efficient in in that respect the oar being more efficient in the mid
> range closest to perpendicular to the hull.
Ah, the curse of the orthogonal! Sorry, that's another of those false
beliefs that has been hammered to death here on RSR but of course
prevails across the rest of the sport.
It may seem logical that it is best to "push" directly astern, but
unfortunately that's wrong. The mid-stroke iswhere you generate the
puddle, due to loss of hydrodynamic lift & consequent stall & sudden
slip of blade through water. That puddle consists entirely of the
energy which you provided but which did not move the boat - think of it
as the heat & smoke resulting from wheel-spin & you may get a hint of
what I mean. Your propulsive efficiency (conversion of input effort
into useful work) is least in the mid-stroke & highest at the ends of
the stroke. Were it otherwise, scullers would probably have learned not
to use such long stroke arcs, & the fastest crews would have the
shortest arcs.
In truth there's a raft of sound hydrodynamic reasons for a long stroke
arc - once the boat is moving. First it it necessary to appreciate that
the oarblade is not a bat for pushing water, & that its interaction with
the water is most efficient when water is flowing along, rather than
across, the blade.
Sweep stroke rates are
> slightly faster than sculling stroke rates because of that.
But scullers go faster.
>
> 4: The head in the boat linear motion of the sculling rowers action
> allows a greater average force to be applied to the oar. Peak force
> applied I would assume is similar to sculling. But the average force
> that can be applied is less due to the non linear body movement and
> asymmetrical pull.
Probably close to the mark there. As I said, the sweep rower has to
divert some effort into staying in the boat by overcoming the unbalanced
side-loads that sweep rowing generates.
>
> I think those 4 areas cover the differences.
>
> If anybody has links they would like to share that help explain and
> particularly visualize the issues involved I would appreciate it.
>
> Thanks Martin
Beware of helpful links arising out of this sport, please. If rowing
prefers not to understand or engage with its fundamental science,
preferring presumptions & the fond belief that "Obviously it must be
so", then expect the rowing-related links to follow the same path.
The blade end of the rowing stroke is a very complex hydrodynamic
process, fraught with difficulty for those who resist its seemingly
counter-intuitive conclusions. just as one tiny instance: the
propulsive interaction of the blade with the water occurs almost
entirely across the back (convex) face of the blade. It is the internal
tension in the water covering the back of the blade which "locks" the
blade against the water. The surprisingly slight increase in fluid
pressure across the concave front of the blade is largely irrelevant.
But who, in the normal way, would have thought that "unsupported water"
could deliver such tensile integrity? As I say, hydrodynamics is very
counter-intuitive. So the science of rowing propulsion will stay fixed
in the dark ages for as long as it chooses to talk about the orthogonal
being the place to do your work, & about boats being moved by pushing water.
Tinus
> For as long
> as rowers continue to believe there is a perfect style or rhythm, we
> shall keep forcing ourselves back into an unnecessarily constraining box.
For me, the best example of this type of (dogmatic) believe is the
fosbury flop style in high jumping.
The difference between straddle style and fosbury style aren't as big
as most people believe. The record with straddle style is still a very
respectable 2.35 meters in 1978. Also, the straddle style doesn't
require much more height increase of the body centre of gravity
compared to the fosbury style. Still, virtually everyone uses the
fosbury style. Presently, it may be well possible that the style is
not as successful simply because nobody practices and uses it anymore.
If not, still some people with certain specific body dimensions might
be better of with the straddle style.
Walter Martindale
Well... Actually...
The "flop" style of jumping allows the centre of mass of the jumper
to pass under the bar while the body folds itself over the bar. The
"straddle" style requires that the centre of mass of the body passes
over the bar. So - to clear any height with the straddle style of
jump, you need to jump higher than to clear the same height with the
flop.
Please don't ask me to cite the research - anyone currently at a
university with access to the literature online can look it up - I'm
presently not one of those.)
Walter
Tinus
The straddle style also allows the centre of mass to pass under the
bar and is virtually the same as the flop style in this aspect.
Don't ask me to cite the research. I've been looking like hell to find
the original paper which gave me this thought and couldn't find it. :-)
MagnusBurbanks
>
> - Show quoted text -
I used to be a high jumper at school (in the late 70s/early 80s). At
that time on the international stage you regularly saw straddle being
used. I did the Fosbury style. However I can remember being told,
rightly or wrongly, that straddle had the advantage over Fosbury of
allowing the CoM to pass under the bar, but was far more difficult to
learn, the choice was ours. Nobody persevered with straddle for very
long, because Fosbury was a natural extension of the scissors style
and was almost trivial to learn.
Walter Martindale
wrote:
Well let's logic it out. Each thigh is about 10% mass, lower leg
about 5%, feet about 1% each. About 32% body mass straddling the bar
with a certain amount of it below the bar. Torso and head about 60%
body mass has to be above the bar for it to pass over , so even if
you're successful at not bashing the bar while wrapping the legs over
it's got to be a little higher.
Flop style - wrap the body over the bar, bent backwards with most of
the mass under the bar as the upper body passes over, then dives for
the mat while the legs are still on their way up and over - when the
hips are above the bar, the head arms and shoulders, and the bulk of
the legs are under the bar, putting the com under the bar if it's all
averaged out. In the 1970s it was either in James Hay's The
Biomechanics of Sports Technique or in Winter "biomechanics of human
movement" 1979. I've chucked out my copy of Hay, but when I get
unpacked I'll look up my Winter to see if it's there.
Cuddle Bunny
Thank you for your extensive response to the points raised (on rowing
efficiencies not flopping). I do appreciate your input. I need to
educate myself and experiment in some of the points raised before I
can go further in my understanding.
Thank you Martin
Carl Douglas
My pleasure, Martin.
When discussing the inertial & fluid dynamics of rowing, I worry that
the conflict between what we're told, on the water & erg, & what's
actually going on, can boggle the best minds!
Yesterday I spoke with a good sculler who'd ended a spell in a fast-ish
eight. Returning to sculling raised many concerns. Assuming the crew
coach knew best, she worried over the conflict between how she's always
sculled & what the crew did. The eight had greater vertical separation
of feet & seat than is possible in the 1x, & coach had stressed getting
the back over WRT the horizon at the catch. She couldn't emulate that
in the 1x, so assumed it was her fault - why would coach be wrong to
think it so important?
She'd become stiff in the lower back after the spell of sweeping. I
joked that scullers keep pulling when a boat lurches & others take a
light stroke, & sweep asymmetry does the rest - that rang a bell. But I
also suggested that trying in the 1x to get an impossible back alignment
may not be helping.
Then I asked if she'd been told that having feet low/seat high "helped
you get your weight on the feet"? Yes, she had. And had she been told
to "control the slide by pressing on the stretcher during recovery"?
Yes. So she hadn't been told that you'd actually stay at backstops if
you did that? No. But the boat is what experiences the fluid drag that
slows it down, while Newton says your moving body wants to move towards
the bow as the hull decelerates, I said. Ah!, she replied.
There's a lot of plausible hokum around
;)
Charles Carroll
> ;)
Carl
As you wrote in an earlier post: "For as long as rowers continue to believe that there is a perfect style or rhythm, we shall keep forcing ourselves back into an unnecessarily constraining box."
I have been studying frame by frame the slow motion video of Vyascheslav Ivanov at the 1956 Olympics. Three components of Ivanov's sculling leap out immediately. Many coaches I know would consider these components faults to be corrected.
The first component is Ivanov's back, which is rounded, not straight. I can hear a coach from the launch shouting, "You need to sit up straighter."
The second component is Ivanov's rowing the blade in.
And the third is Ivanov's "arm grabbing" at the catch.
Yet Ivanov in the 1956 Olympics will win gold.
But how can he do this if he is rowing so poorly?
Doesn't this beg the question - is Ivanov actually rowing so poorly?
Or is it that he is just not forcing himself into "an unnecessarily constraining box" based on some fanciful belief that there exists such a thing as "perfect style or rhythm?"
How can anyone say that Ivanov is rowing poorly when his blade insertion is all but perfect?
Ivanov squares late, he keeps the blades off the water and poised, and he strikes so fast that there is almost no discernible splash. I have never seen such a clean entry
Even more enviable is Ivanov's blade insertion, which is not a sequential movement. By this I mean that he doesn't put the blade in and then pull. Rather he uses a blended movement - inserting, driving and drawing all at the same time. I suspect this probably explains the "arm grabbing" at the catch. In any event, Ivanov's quickness of the force increase at the beginning of the drive is just blindingly fast.
Oh well .... As usual I go on too long. Better I stop thinking and just go sculling.
Cordially,
Charles
Dave Sill
> I have been studying frame by frame the slow motion video of Vyascheslav
> Ivanov at the 1956 Olympics. Three components of Ivanov's sculling leap
> out immediately. Many coaches I know would consider these components
> faults to be corrected.
For reference, here's the link to your slo-mo video:
http://www.youtube.com/watch?v=UVxVisaz_nI
> The first component is Ivanov's back, which is rounded, not straight. I
> can hear a coach from the launch shouting, "You need to sit up
> straighter."
>
> The second component is Ivanov's rowing the blade in.
>
> And the third is Ivanov's "arm grabbing" at the catch.
The fourth is that he's rowing too deep.
> Yet Ivanov in the 1956 Olympics will win gold.
That's the bottom line.
-Dave
Carl Douglas
But you missed his feathering of the finish underwater! Didn't you know
that's yet another "fatal fault" which is bound to stop you winning
anything - except maybe the odd Oly Gold?
Being a tad more serious: note Ivanov's complete lack of dwell or hang
before the catch in the last of Charles' excerpts.
Cheers -
Dave Sill
> But you missed his feathering of the finish underwater!
Yeah, and I also missed his horrible 1:1 ratio.
-Dave
che...@rgc.aberdeen.sch.uk
Sculling is only faster because there is a bigger overall blade area
--
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Henry Law
> Sculling is only faster because there is a bigger overall blade area
we've had instances recently of people following posts more than a
decade old!
But to your point: in what way does overall blade area increase boat
speed? Perhaps there's less percentage slip with a large blade; I
couldn't say (though I know a man who could ...). But I doubt it's all
that great when comparing a sweep blade with a sculling blade. And what
about the fact that said sculling blade is on a shorter loom?
--
Henry Law Manchester, England
Carl
> neither of you win.
> Sculling is only faster because there is a bigger overall blade area
>
desire of some to appear instantly expert. The rowing stroke is far
more complex than you seem to appreciate.
Take time, ask nicely & someone may eventually find time to explain.
But there's no point in explaining a complex subject to someone who
thinks they already know it all.
Cheers -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells
Kit Davies
> Sculling is only faster because there is a bigger overall blade area
>
July 2010 can be found here:
https://groups.google.com/forum/?hl=en#!topic/rec.sport.rowing/WNiccCBhvJU
(and it was quite a good one)
Kit
thomas....@googlemail.com
> On 08/03/2015 19:25, che...@rgc.aberdeen.sch.uk wrote:
> > neither of you win.
> > Sculling is only faster because there is a bigger overall blade area
> >
>
> The application of real science to rowing is continually hindered by the
> desire of some to appear instantly expert. The rowing stroke is far
> more complex than you seem to appreciate.
>
> Take time, ask nicely & someone may eventually find time to explain.
> But there's no point in explaining a complex subject to someone who
> thinks they already know it all.
Someone call Team GB.
Leo
allometric scaling where power varies according to m^3/4) in
claiming to have finally settled the reasons for why sculls are more
efficient than sweeps.
See:
Pelz P. and Vergé A.,
"Validated biomechanical model for efficiency and speed of rowing",
J. Biomechanics, 47, 2014, pp. 3415-3422.
Kleshnev disagreed (although he found some of Pelz's matrix arguments
"non-understandable") preferring the scaling "laws" of McMahon and
of Dudhia. See:
Rowing Biomechanics Newsletter, 2014 November.
mruscoe
> Pelz and Verge used some very elaborate scaling arguments (including
> allometric scaling where power varies according to m^3/4) in
> claiming to have finally settled the reasons for why sculls are more
> efficient than sweeps.
> See:
> Pelz P. and Vergé A.,
> "Validated biomechanical model for efficiency and speed of rowing",
> J. Biomechanics, 47, 2014, pp. 3415-3422.
>
energy dissipated into the puddle (vortex wake) in the mid-stroke stall
- in which case are they not missing a significant part of the
difference between the rowing and sculling strokes?
marko....@gmail.com
cruzen...@gmail.com
> A buddy from my rowing club and I have a little wager on the question,
> "Why is a sculling boat faster than the comparable sweep boat (i.e.,
> double vs. pair, quad vs. four, octuple vs. 8+)?"
>
> He says, essentially, that the difference in speed is about the boat.
> In sweep rowing, forces are asymmetrically distributed to the hull,
> causing unproductive torque and side pressure. Sweep rowers and
> scullers generate about the same amount of total force, but in sweep
> rowing, more of that force is lost to the hull, so less force can be
> translated into boat speed.
>
> I say that the speed difference is about the inherent biomechanical
> efficiency of sculling (applying muscular energy and body movement
> symmetrically using two oars) versus sweep rowing (asymmetrical body
> movement and application of muscle strength to a single, bigger oar).
> Because sculling makes more efficient use of the athlete's strength
> and body movement, scullers are able to apply more force to the
> footstretchers, so the boat goes faster. Modern shell construction
> methods and materials minimize any loss of energy from the system
> arising from asymmetrical distribution of forces on the hull in sweep
> rowing.
>
> Who wins the bet?
SingleMinded
What it did show, however, was what one of my coaches always said: "scullers can row, but rowers can't scull".
Henry Law
> It wasn't an octuple scull (I've never seen one of those racing with a crew older than J14).
(Better still in this
http://nlroei.nl/system/fotoassets/200107/108/9286/medium/332-3227_IMG.jpg?1325282886
)
she...@mckenzieweb.co.uk
When I get round to revarnishing it, you are welcome to come and row Goring Gap's octuple - always a popular boat with our recreational rowers (and we are more J70 than J14).
Andy
Henry Law
> When I get round to revarnishing it, you are welcome to come and row Goring Gap's
> octuple - always a popular boat with our recreational rowers (and we are more
> J70 than J14).
is just about right for me ...). Goring Gap is a wonderful club; I have
a great soft spot for it, from up here 200m away, principally for this
reason:
https://groups.google.com/forum/#!topic/rec.sport.rowing/0glfuk9sylo/discussion
Chris A
magnus....@gmail.com
Chris A
> I was at FISA Masters in Vichy in 2004, I think, where for a bit of (marketing) fun Stampfli put together several mid-sections of eights to create, I think, a 27x. I didn't scull in it, but it was an impressive sight.
dyla...@gmail.com
> A buddy from my rowing club and I have a little wager on the question,
> "Why is a sculling boat faster than the comparable sweep boat (i.e.,
> double vs. pair, quad vs. four, octuple vs. 8+)?"
>
> He says, essentially, that the difference in speed is about the boat.
> In sweep rowing, forces are asymmetrically distributed to the hull,
> causing unproductive torque and side pressure. Sweep rowers and
> scullers generate about the same amount of total force, but in sweep
> rowing, more of that force is lost to the hull, so less force can be
> translated into boat speed.
>
> I say that the speed difference is about the inherent biomechanical
> efficiency of sculling (applying muscular energy and body movement
> symmetrically using two oars) versus sweep rowing (asymmetrical body
> movement and application of muscle strength to a single, bigger oar).
> Because sculling makes more efficient use of the athlete's strength
> and body movement, scullers are able to apply more force to the
> footstretchers, so the boat goes faster. Modern shell construction
> methods and materials minimize any loss of energy from the system
> arising from asymmetrical distribution of forces on the hull in sweep
> rowing.
>
> Who wins the bet?
Dylan MacQuoid (Rower for Albany Rowing Center)
robin_d...@hotmail.com
Likewise, the quickest some of our (pre-1982) Carbo IVs have ever gone was when they've been rigged with a set of >40-year old iron rigging - we won a head race on the Clyde a few years back with a boat that was easily >30 years old at the time against rather fresher boats rowed by the opposition. Admittedly, we tended to get R2 level rowers in the quad, where the same shells were used for MNov/WNov4+ at the same event. A WNov4x+ will go faster than most MNov4+ in the same shell, usually because they're not trying too hard with the arms and listen to coaching advice instead of hauling on it!
The 1x tends to be quicker than the 1-.
Robin (Mostly retired rower, Coxswain, Equipment Manager, Coach, committee member etc for Dundee UBC, Scotland & Vancouver RC, BC)
John Greenly
> The 1x tends to be quicker than the 1-.
--John
