Theoretical hydrodynamic coefficients of laterally oscillating profiles at high Froude number (for surface effect ships)

Abstract

Surface effect ships are envisaged which may exceed 100 knots speeds and 10,000 tons weight. Their lightweight structure leads to the possibility of hydroelastic instabilities and dynamic amplification of loads due to waves. Literature surveys indicate that hydrodynamic coefficients for lateral oscillations of slender profiles at high Froude number do not appear to have been studied. This paper describes initial phases of the determination of theoretical coefficients as an expansion in inverse Froude number, for moderate draft to length ratio, and very low frequency lateral motions. Integral equations are formulated for various orders of terms in a series expansion in inverse Froude number for hydrodynamic coefficients due to sway, roll, and yaw of a profile. Zerothorder terms are determined explicity, first-order terms implicitly. Explicit first-order terms will be the subject of a subsequent paper.