The ideal stroke would have the largest amount of force possible at the very instant the oar was dropped into the water. This force would be maintained over the distance of the stroke and stopped when the oar is instantly taken out of the water at the finish (Figure 2). Boat velocity is a function of the average impulse not peak power or length of stroke independently. The impulse of the drive is strongly correlated with the physiological limitations of the individual. Maximal oxygen consumption (liters/min) determines the total area of the curve.
Figure 2 (Seiler)