Surface Piercing Propeller Performance

This thesis addresses possible improvements in the efficiency (thrust) of surface piercing propellers; in particular with respect to the angle of the propeller shaft came to mind. Preliminary calculations based on the basic pitch/diameter geometry suggest that about 3-5% efficiency is lost if the shaft is parallel to the flow, compared to skewed a few degrees in the "paddlewheel" direction at certain speeds. More accurate calculations based on the lift characteristics of each blade, on the angle of attack and the flow of water over each blade and given a set of basic assumption on the over all performance of each blade, as the blade enters and leaves the water; are used to determine the increase in efficiency. Full scale experimental results are also presented in support of the calculations.