The influence of heel on the hydrodynamic coefficients of ship like sections and a trawler form

Abstract

Applying a strip theory approach together with multiparameter conformal and multipole expansion techniques the coupled hydrodynamic coefficients associated with heave, roll and sway parasitic motions are determined for a heeled, transom stern trawler. The trawler is stationary and oscillates with small amplitudes of motion about an initial heeled position of $0^{\circ }$ (i.e. upright, symmetric underwater form), $5^{\circ }$ , ${10}^{\circ }$ , ${15}^{\circ }$ and ${20}^{\circ }$ . An assessment of the influence of underwater hull form and frequency of oscillation on the hydrodynamic coefficients is included as well as a limited comparison between theoretical predictions and experimental data for heeled ship like sections. The degree of coupling existing between the hydrodynamic coefficients associated with the symmetric and antisymmetric parasitic motions is closely related to the non-symmetry of the underwater hull form and not necessarily directly related to the angle of heel.