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What is Power? July Masters Feature
July 10, 2012
The racing season is upon us. For many of you, doing well in your race is the goal of many long months of training. To improve on past results, you need to be able to make the boat go faster. We know that what slows the boat down is water resistance on the hull. That resistance is proportional to velocity cubed. This means that at twice the speed, the resistance is proportionally eight times as much. Therefore, to go a little bit faster takes a lot more energy, or in other words, we have to generate a lot more power.
What is power? The equation is quite simple. Power = Force x Distance/Time. Force is Mass x Acceleration. Distance is the effective length of your stroke. Time is the time that the blade is in the water with a force applied. To simplify it, we are accelerating our mass through distance over a period of time. So how can we improve our power production? To answer, just look at the components. We must connect all of our mass to the oar, so it is convenient to think about the center of mass and trying to use it on the oar. We want the rate of acceleration as high as possible throughout the stroke, so this would preclude jerking at the catch or tugging at the finish. The range of motion wants to be as long as we can comfortably make it, which means that a good catch is needed and keeping weight on the oars at the finish is a necessity. We want the time of the drive to decrease but only by making the boat go faster. It would be nice if we could always be on the drive. Time on the recovery needs to be efficient so that we can reposition our mass to take the next stroke. Taking more strokes per minute allows us to produce more power during that minute span. Higher stroke rating is necessary for the shorter 1,000-meter races, but efficiency is also very important. One of the key ways of thinking about it is that you are always moving, and how you move the mass back and forth is what is important.
These are the overall principles of boat speed and power. The details of how you do it will lead to your success. Many of these details we have talked about in past articles and will continue to do so in future articles. Good luck at the races!
For those of you who know John and I, you will have already figured this out, but to the others, I need to give credit where credit is due. This month’s article was written by John Dunn, the engineering half of our coaching duo.
Charlotte Hollings and her husband, John Dunn have spent more than 70 years immersed in the sport of rowing. Both have rowed on the U.S. National Team, winning several international medals. Charlotte’s coaching career has taken her west to Stanford University before heading back east to Boston University and then Cornell University. John remained close to home, coaching at his alma mater of Cornell University for 18 years, first as the frosh lightweight coach, then varsity lightweight and finally varsity women. In 2001, Hollings and Dunn started the sculling camp Calm Waters Rowing in Lancaster, Va. For more information, visit www.calmwatersrowing.com.