In the Olympics, you won’t see anyone win a rowing event without a paddle, but it turns out that you don’t really need one for a canoe or paddleboard. How can you get around when you’ve lost your paddle? You stand up on one end and start bobbing. This is known as gunwale (pronounced gunnel) bobbing, and it’s pretty impressively effective! With optimal parameters, scientists found that a canoe could move about 1 m/s with the technique.
As the bobber pushes, it generates an asymmetric wave field on the water surface. The canoe or paddleboard then essentially surfs those waves, turning the vertical displacement into a horizontal thrust. The researchers expect that the effect matters for competitive rowing, too, where the athletes’ rowing motions cause some vertical displacement. Clearly, the biggest effect comes from the oars themselves, but optimal bobbing could provide enough of an edge to ensure the gold. (Image credit: top – R. Chisu; others – G. Benham et al.; research credit: G. Benham et al.; via APS Physics; submitted by Kam-Yung Soh)
Related topics: Optimizing oar length, vorticity around an oar, and a vibration-propelled biorobot
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