# The Physics of Rowing

## Introduction

 Fig. 1: The Eight Olympic Rowing Classes for Men. (Source: Wikimedia Commons)

Rowing is often touted as one of the hardest sports in the world. [1] The mental toughness required to keep your body in excruciating full-body physical pain for the entirety of a six minute race is second to none. Yet, at the top end, everyone can do this. And most people have very similar physiological traits, but races can still end up very one-sided. So what is the difference between the crew that wins and the crew that loses? How do some rowers maximise their efficiency and make the most out of every watt of power they apply to the footplate, while others get left many lengths behind? The answer, clearly, boils down to the physics of each stroke.

## The Rowing Stroke

The rowing stroke works through Newtons 3rd Law. You use an oar to push water in one direction, and as a result you are propelled in the other. The more water you can push at a greater speed, the faster you will be propelled backwards. The same goes for your weight: the lighter you are, the faster you will go (all else being equal). All international rowing races are competed over a distance of 2000 m. This typically takes an elite crew anywhere between 5.5 and 7 minutes, depending on boat class (see Fig. 1), weather conditions and gender. The average international male athlete will output an average of between 480 and 600 watts during a race. The average international female will output between 300 and 380 watts during a race. If we say that an average international male eights race is 5 and a half minutes and the average athlete in each boat is producing 540 watts for the whole race, we find that each athlete produces a total of:

540 W × 60 sec/min × 5.5 minutes = 1.78 × 105 Joules

per race. Clearly the most important thing is to translate the power applied to the handle through to the water. This is why having a stroke in which no water is missed (that is, where the blade of the oar enters and exits the water at the extremities of the rowers movement) is so important when it comes to efficient application of power. Even a small, 10% shortening of a rowers effective stroke length, can have drastic effects on boat speed. Take the 540 watt average we considered above for example, and you see that applying just 10% of total power outside of the water results in only 486 watts being applied to the water - putting them at the lower end of international male power output.

## Conclusion

The world's most effective rowers are those that can turn the power they apply to the oar handle into moving water with the least amount of wasted energy. Maximizing effective length is a key focus of many international rowing programs around the world and with good reason: when it comes to the top end, efficiency is usually the deciding factor.

© Misha Wilcockson. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

## References

[1] V. Martinez, "The Five Toughest Sports at the Olympics," The Irish Times, 18 Aug 16.