A formalism based on simple physics that predicts the variation in boat velocity throughout the rowing stroke is presented and is applicable to all classes of rowing. Predicted boat velocity-time profiles throughout the rowing stroke closely match experimental profiles in both shape and amplitude. The formalism also identifies a primary cause of boat deceleration at me start of the power phase (blade in the water) as a detrimental lever action of the oar. This detrimental lever action occurs when the net rowing force acts in an opposite direction to the intended direction of boat travel, irrespective of hydro-dynamic drag contributions. The detrimental lever action is minimised if the line of action of the force applied to the oar-handle by the rower is maintained as parallel to the long-axis of the boat as possible, a finding consistent with current coaching strategies. For oar-handle forces applied at 10, 20, 30 and 40°to the long-axis of the boat, the lever system is predicted to operate detrimentally at catch angles above 67, 49, 35 and 27°respectively for an oar length of 3.4 m and rowlock-to-centre-of-hands length of 1m. The findings provide additional quantified insight into observations and predictions made by other authors (e.g., Pope, 1973; Martin & Bernfield, 1980) and indicate that relatively large catch angles, e.g., 60 to 65°, may in some respects be detrimental to rowing performance.
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