Prediction of the Complete Second Order Wave Drift Damping Force For Offshore Structures

Wave drift damping on floating bodies performing slow motion in all the three horizontal modes surge, sway and yaw is considered. The coupled radiation-diffraction problem is formulated in a relative frame of reference, and the 3 x 3 monochromat ic wave drift damping matr ix is developed consistently to second order in the wave ampli tude. The bodies may be of general shape, and the depth arbi trary. Explicit formulae suitable for numerical calculation are obta ined and implemented into a low order panel program. We here apply the model to four different offshore structures, and the results show tha t the wave drift damping force has an importan t contr ibution to the mean second order wave force.