Free fall lifeboats have been developed for emergency evacuation from offshore installations, when conventional means of transportation cannot be applied. As a consequence, the ability of the lifeboats to perform safe drop- and sail away under all circumstances has to be demonstrated. This paper focuses on efficient and robust numerical simulation of these operations.To predict the lifeboat behavior under a large variety of stochastic conditions, such as irregular waves, in combination with wind and current, calls for many individual simulations of the sailaway performance. The present paper presents a brand new mathematical model that is able to predict the behavior of a free fall lifeboat during drop-phase, the submerged phase, the surfacing phase and the 'sailing in waves' phase (combined, not gluing time traces from different predictions together).