Excess wave-making

Excess wave-making is the rise in resistance, above a frictional baseline, that grows steeply once the Froude number passes about 0.4, as the diverging and transverse wave systems of the bow and stern reinforce. In the Froude decomposition total resistance is frictional plus residuary, the residuary being dominated by wave-making at speed; the residuary coefficient C_R shows humps and hollows from bow-stern wave interference at Froude numbers near 0.3, 0.4, and 0.5. Michell’s thin-ship integral and Kelvin wave theory describe the radiated pattern. Designers fair the hull, add bulbous bows, and limit Froude number to suppress this component, since wave-making can exceed friction at high speed.