Could I have been mistaken for 30 years about how to make a rowing shell fast?
December 4, 2009 by Mike
Filed under Get Fast, Rig Differently, Think Different
I’m currently at USRowing’s Convention, in Phoenix.
A convention, and certainly this one, is a great time to learn new things. And in this case one of those new things is a piece of info that may cause several sleepless nights for coaches, and rowers. It will for this coach.
For all my years of coaching I went by the mantra that the hull of a boat moves the fastest at the finish, after the drive is over and the blade is just being removed.
Good chance (darn good chance) that this is not so. That I was mistaken for 30 years is a real ego knock.
Why do I think I was wrong?
I spent about an hour discussing a very interesting project with the creator—Jim Mitchell of PowerView.
In essence his combination of GPS, video, accelerometer graphs out that the fastest part of the stroke may well be the catch. (I always thought it was at the release.)
This is an image of some of his results.
I’m not going to be able to explain it well here, but he has videos and info on his site.
I’m going to really suggest you go there and check it out.
And I’m going to have a sleepless night.
(Hey—this is not some affiliate deal. It is, though, something big, a great paradigm shifting piece of info that could really make a difference to your rowing.)
(Let me know what you think!)
Dear Mike
Thank you for your interesting information for me.
I’m a reader of your message in Japan.
I’m very interested in the profile of hull speed during one stroke.
Now I’m trying to simulate the hull speed via the movement of the mass of body weight and the friction force from the water in my personal computer with Microsoft Excel (not using super computer for the simulation).
Its aim is “not” to get a accurate speed, but to get a visible image of speed profile for my rowers.
For example, the correspondence between the profile of power curve of a rower and the profile of the hull speed in one stroke.
I want my rowers to understand the effective power output to the blade to get the most effective hull speed.
In my studying, I feel that the friction force from the water has more impact to the hull speed than my expectation.
So the max hull speed is at the middle of the stroke, or at the phase of forward at high speed of body mass especially at high rate paddle.
This is my present image.
Toshio
Mike,
I saw the demo at the Convention also, and am going to put one on my Varsity Boys boat when Jim swings through San Diego.
I have been pondering this also, and have come to the conclusion with proper technique (i.e. don’t do anything to slow the boat down…) the boat can actually continue to accelerate on the recovery, and be at its fastest right before the catch. The Powerview videos I saw at the convention and on their site seem to confirm this. Just watch the instantaneous hull speed during the stroke cycle, and you will see it continue to increase up until the catch, where it takes a dip as the blade enters the water.
Kevin Sauer spoke of this in the Level III Clinic yesterday, and demonstrated technique I have been teaching my Juniors to maximize run of the boat. I would love to speak to you further about this at the convention today.
/Art Sloate
San Diego Rowing Club Junior Crew
Watching one of the videos on the PowerView site that your provided, and stepping through the video in as close to frame-by-frame as I could revealed that the slowest velocity recorded was at the catch and the fastest was at the finish. The stroke of that boat had a fairly slow catch and tended to dip his hands a bit before the catch, perhaps causing a slower than normal boat speed at the catch. If so, then perhaps the findings of hull speed cannot be generalized across all boats as suggested here.
I’d love to hear your comments. What would be truly interesting is to coach that pair and see in a similar video if by changing their catch, for example, it’s possible to show increased speed at the catch.
Which lens was used with that pair?
Due to friction the boat is always slowing down when not being propelled. whenever a stroke it taken the blade has to catch up to the boat before it can begin propelling.
Think of the stroke as a solid line, with dotted sections at each end representing when the blade is either catching up or slowing down.
The catch is the fastest part of the stroke, it’s the only time when the entire body is used simultaneously, in a proper power curve maximum speed it attained almost immediately achieving a near perfect horizontal line with a steep drop-off.
if the curve looks like a mountain then there’s a problem with the rower’s legs not being fast enough.
A proper recovery is done with quick hands around at the finish, quick around and away. This will in effect relax the rower allowing the boat the run under them.
Once the body angle is set the boat runs under the rower, an experienced rower can actually pull the boat under them, do not mistake this for rushing the slide, the boat can be pulled along giving actually giving and extra amount of distance traveled.
http://www.youtube.com/watch?v=Q1nxJCVFUnc&feature=related – watch the white single and you can see him gaining an extra little bit of distance on the recovery giving a perception of acceleration when in reality it is still traveling at the same speed.
Proper analysis of rowing requires knowledge of frames of reference, ie the rower relative to the shore, boat or water. relative to the boat the rower does no work over one stroke, the seat simply ends up in the same spot, relative to the shore the rower does giant amounts of work moving the boat down the course. Relative to the water you can think of the rower flinging the boat along using the blades and pulling the boat behind them on the recovery.
because of a lack of understanding of just how to even observe rowing, many pointless arguments are undertaken when in reality both people are actually observing the same thing but with different ways of explaining.
@ all: A lot of solid responses and I would suggest that some of you consider beginning a conversation directly with Jim Mitchell.
If you watch any sculler/crew boat during the stroke and forget that in most cases the camera tracks the average position of the crew/boat, you can easily be distracted to think that the athlete moves backwards and forwards on top of the boat, because he/she/they move back and forth in the camera image.
Observe the passage of the boat/crew system against the background. You’ll see that during the recovery the body/crew is still progressing in the direction of the finish line – even the hands in a “quick hands” start to the recovery – they’re going towards the finish line – and the boat still (somehow) goes past the rower/crew to get set up for the next catch.
The only way this is possible is from a “draw” or a “pull” from the feet. Richard Smith of Sydney Australia has shown about 100 N of “pull” on the foot stretcher in a single during the recovery. There’s no real other way for the boat to get to the catch position.
Velocity curves from various methods show that the peak hull velocity occurs in about the middle of the recovery (including some of the curves generated (unpublished) in my master’s research).
Some coaches (see Tonks’s discussion in Rowing Faster (Nolte, 2005) use the expression “sit there and let your feet come towards you” or something similar when coaching the recovery.
Look out of the boat next time you’re sculling – during the recovery you continue to travel towards the finish line while the foot stretcher gets closer to you. this is an indication that the boat HAS to speed up during the recovery – your body mass gives up some speed to the hull to get the boat ready for the catch, but then recovers some of this speed when getting to the end of the recovery. However, once the blades are out of the water, there’s no propulsion, and the combined velocity of the crew and the boat must decelerate unless you’re rowing down a pretty steep hill..
Walter
a bot has run, i.e. the speed at which it is traveling, a rower never has to pull themselves up the slide necessarily, if the rower, say in a single, has quick hands away and a relaxed body the boat runs under them. this is possible due to the sliding seat. both the rower and the boat are indeed traveling at the same speed, here’s where it get’s a little strange, the rower can change the speed of their body relative to an observer on the shore. it’s a if say a motorboat is driving along a lake with a ball on it, as long as you hold it there it stays at the same speed, the rower not moving, if you let it go it should stay int he same place unless you give it a tap it will go to the stern of the boat (quick hands away provides the force) and if the body is relaxed the boat can run under the rower and in effect the speed at which the hands are sent away can control the rate
I think the biggest issue with the current discussion is the fact that similar terms are being used to describe very different things. It sounds like what Mike is referring to is the velocity of the shell itself. Due to conservation of momentum, when the rower and the stern of the boat try to move towards each other, the boat will move far more (and far faster) since it has less mass.
@ Matthew Chase: What you’ve analyzed is the velocity of the SYSTEM rather than the velocity of just the boat. If you take into account everything else (rower, boat, oars, etc.) then you’re absolutely correct: velocity is low at the catch and high at the finish. However, what I believe Mike and Jim are proposing is the velocity curve of the boat on it’s own.
@Alex: You’re confusing velocity and force. The “ideal” force curve you described is exactly that: a FORCE curve and NOT a velocity curve. So while the maximum force should be applied as immediately as possible from the catch, applying that same force from catch to finish (the “square” curve you described) will result in a constant acceleration of the system from catch to finish due to F=ma laws. In general, if there’s constant acceleration on a system, the highest velocity of that system will be right at the end of that constant acceleration (i.e. the finish).
I propose an interesting idea to everyone, since I’m thoroughly enjoying this discussion:
Since the maximum boat velocity is on the recovery, the only reason to control the recovery (in essence, control/slow down the speed of the boat on the recovery) is to minimize the negative acceleration of the boat at the catch, i.e. the “check”. This negative acceleration would be caused by a crew who’s unable to get their blades in quick enough or the power applied to the blades quick enough to counteract the high negative acceleration. Therefore, if you have a crew that is really sharp around the catch (quick blade entry, picks the boat up quickly), they could basically “rush” the recovery with negligible negative effect on the average velocity of the boat. Any thoughts?
@Ian: You are right, and I submit that velocity of the boat is what we are working for. As for rushing the recovery, I observed that in one of my junior quads yesterday morning. I believe they got away with it because they were very light (60kg ave). I have yet to see a heavy crew get away with it…
@Ian that’s a good analysis, my wording is a little off there but you can use the force curve to figure out boat speed, and yes F=ma, but there are a number of resistive forces acting as well, so ralistically the boat never has constant speed
Your comment about experienced crews rushing the slide I agree with entirely. Its comparable to jumping of a table and landing softly which requires controll in the last 2 inches. I figure its like the taboo of the rowing world. Its easy to see well implemented in a single and would be greatly effective in a crew boat but difficult to co-ordinate.