I’m sure that you’ve heard that there are two ways to make your boat move faster – either row harder or row smarter. This article will go over some of the fundamental physics behind rowing, which should help you with your technique and the second half of the idiom.
Whether you’re in a sweep or sculling crew, an eight or a single, your boat still has the same basic setup. You sit on top of the water, facing backwards, accelerating your boat using your blades.
First, let’s outline the most elemental forces acting on the rowing boat. Buoyancy is pushing the shell upon the vertical plane, and your weight and the shell’s weight are pushing the boat down into the water. The horizontal plane has opposing forces of drag and thrust.
To move as quickly as possible, you want to minimise the drag on the shell and increase the thrust. The most significant cause of resistance is the friction of the hull moving against the water. Therefore, you want to minimise the total quantity of hull in the water and make it as easy as possible for the boat to pass through the water. Most of this is in streamlined and lightweight boat design, but your rowing technique can also diminish resistance. For example, by avoiding the temptation to move all of your weight to the bows in a strong finish, you can prevent submerging more of the bows in the water, thus reducing overall resistance.
Everyone’s favourite physics quote – Newton’s third law – explains how the boat moves through the water (‘every action has an equal and opposite reaction’). You push water away with your blade, and the boat moves in the opposite direction. The more water you can push, and the faster you can push it, the faster your thrust force is, and the faster you will move. The blade is a class one lever – it has the load (water) at one end, the fulcrum (gate) in the middle and the effort (you) at the other end. This gives the equation Load = (Inboard distance / Outboard distance) * Effort. It is worth noting that the effort on the blade varies as the blade moves through the water as you engage different muscles.
On nearly all rowing blades, the outboard length is significantly longer than the inboard. If you increase the inboard length (by changing the oar length or using clams), you will make the load feel lighter, and decreasing it makes the load feel heavier.
This was a very quick low-down of some of the forces acting on your shell as you move. Hopefully, it will help you to transfer your power to boat speed more effectively!
If you’re interested in this area, try:
The Biomechanics of Rowing, book authored by Dr Valery Kleshnev
Or, take another look at this subject in our interview with Dr Kleshnev
That’s all for now. If you’re hungry for more, check out any of our other pieces from The Catch, listen to the latest podcast episode, or flick through our race previews.
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