Optimal Drag in an Accelerating Rowing Blade *

We report on the drag on an accelerating plate below a water surface that mimics part of the propulsive forces of a rowing blade. The motion of the plate is generated by a dedicated industrial robot that can reach the velocities and acceleration encountered in actual rowing. Measurements of the drag force are combined with flow visualisations and PIV measurements. Here, the depth under the free water surface was varied, as well as the blade acceleration and terminal velocity. It was found that there exists an optimal depth where the drag force exceeds both drag values of the blade touching the water surface and far below the water surface by 50 per cent. This implies that there would be an optimal depth for a rowing blade.