Various objects, such as containers and barrels lost from cargo and container ships, can drift at sea. When remaining afloat they can be dangerous obstacles to navigation and in any case a danger for environment. The description of their probable trajectories is a key point for their location and recovery (Daniel et al, 2002). A simplified theoretical model based on the equilibrium between steady drift forces and viscous drag forces is proposed to calculate the steady drift velocity in waves only, without effect of wind nor current. Several comparisons with experimental results obtained from trials in a wave tank are given for cylindrical and box shaped objects.
