Abstract
The seakeeping behavior of a bulk carrier with four wing sails is investigated in regular
waves. A time-domain simulation framework, which combines seakeeping and maneuvering, is applied
in the study. The simulation framework is validated against experimental data, without sails, with
reasonable agreement. In calm water with wind from the side, the sails contribute with 48% of the
total thrust. Simulations in head wave conditions show a negligible effect of the sails on wave induced
motions and added power. In beam sea, the amplitude of the roll resonance is reduced by the sails,
while only minor differences are seen for other wave periods. However, the added power in waves for
short wave periods, is higher with sails compared to without. This is caused by high drift angles, which
reduce the angle of attack and the thrust from the sails. The high drift angles were caused by the mean
second-order yaw moment, and was also observed for simulations without sails. This emphasize the
importance of also including transverse second-order wave loads in predictions, and not only the added
resistance in waves.