Does the ship’s motions in waves affect the wind propulsion performance?

This is one of the questions that the OPTIWISE project has looked into. The first results were recently presented at the INNOV’SAIL 2023 conference in France.

The OPTIWISE project will develop several wind-powered ship concepts and evaluate their performance. To do so, the existing methods for performance evaluation of wind-powered ships have to be progressed. Up to now, the performance assessment methods assume that the air flow is steady. However, as all sailors know, the wind in the open sea is never constant. Moreover, when a ship sails in waves it rolls and that will make the air flow over the sails to change all the time. Will this affect the performance, compared to the steady prediction?

To answer this question, RISE SSPA Maritime Centre set sail on a generic ship and simulated its performance in a numerical seakeeping code. A wind variation model was implemented, which simulates the natural fluctuation of the wind in time and space. The analysis showed clearly that the unsteady wind conditions affect the predicted performance. The researchers will now continue to investigate the consequences for performance modelling and for the optimisation of control system of various types of wind propulsion systems.

Read the full article: Kjellberg, M., Gerhardt, F. & Werner, S. Sailing Performance of Wind-Powered Cargo Vessel in Unsteady Conditions. in (2023).

Seakeeping simulations with SHIPFLOW MOTIONS of a generic wind powered ship with wing sails.

Snapshot in time of the longitudinal velocity component of the spatial wind field over a 200 m× 200 m × 100 m box

Martin Kjellberg, RISE SSPA Maritime Centre presents the work at INNOV’SAIL 2023