I’m always jealous of other sports with the resources to conduct actual scientific research on the physics of performance. Crew and sculling are among those sports. The R&D is aimed to investigate and optimize every possible aspect of performance to hopefully yield multiple avenues for improvement. Perhaps we will never see full carbon-Kevlar dragon boats weighing less than 250 lbs, but I love reading this stuff because it makes my wheels turn in hopes that some trickle-down truth can help us in our traditionalist sport. After all, each of our sports utilize glorified sticks to push water in order to propel a hollowed-out log carrying people.
There are many potential areas where energy can be wasted, starting from the very chemistry that powers our cells into performing work. This particular article takes a stab at investigating what factors signficantly influence rowing efficiency.
At one point in my life, the mathematics presented would have made much more sense and I may have had more thoughts on this, but for now, I’ll just say “duh” and move on.
Interestingly, the study found that blade efficiency increased as boat speed increased. Based on the curves in Figure 2a, it would seem that there would be some point at which efficiency plateaus or perhaps even decreases as boat speed continues to climb. I always felt that in dragon boat, getting “good pulls” in dragon boat was affected by boat speed. When the boat is at a full stop, the water feels thick and I feel like I can apply a great amount of force to the water. As the boat starts to pick up, those heavy pulls become lighter and lighter still, which would seem to me that my strokes are not as efficient at those higher hull speeds. I would speculate that having better stroke technique designed for higher boat speed is important for improving blade efficiency.
Interestingly, Dr. Kleshnev notes a decrease in boat efficiency as stroke rate increases. I thought this section was simply better written for my smooth brain to understand. Decreasing the “drive/stroke ratio” would mean either decreasing time spent in drive phase (period where blade is in the water) or increasing time spent on the stroke (entire time spent between drive and recovery). Decreasing drive time could mean exiting sooner, but that would also decrease total stroke time. “Fast through the water” is another way to think about it and would be assisted by higher boat speed. Increasing the time spent out of the water could also work to increase stroke time, but while it may be beneficial to “let the boat glide” spending an extreme amount of time not propelling the boat allows the boat to slow down between strokes.
Combining his 2 findings on boat efficiency, one might speculate that (at least in rowing) increasing stroke rate lead to a increase in drive/stroke ratio. At higher rates, I’d think stroke time must decrease in order to fit in more strokes per minute. If recovery were quickened to fit in a higher rate but boat speed did not allow for drive time to decrease (leaving a long drive time due to slow water), the ratio would be increased. Indeed, the conclusive statements suggest shortening drive time as a way to increase efficiency at higher stroke rates.
Application to Dragon Boat Paddling (to be continued)