A CONTROVERSIAL ASSUMPTION CONCEALED IN PERFORMANCE PREDICTION

Some questions are raised concerning traditional thinking on calculating ship performance, and some new formulas are proposed. The assumption referred to in the title is that in using open-water measurements for any purpose in ship design, the characteristics determined in the uniform onset velocity of the open-water test will serve, instead of the characteristics that apply to a ship model when propelled and when the screw operates in a completely different velocity field governed strongly by the shape of the hull upstream of the screw.