An experimental prediction method of power increases of a cruise ship with podded propulsion in waves

  Objectives  This paper aims to expand the prediction method of a power increase in waves for ships with podded propulsion, and to predict the power increase of a luxury cruise ship in actual seas through model experimentations.

  Methods  A self-propulsion test for a cruise ship with podded propulsion in waves is performed in the towing tank. A tailor-made dynamometer is installed inside the model scale pod unit for torque and revolution measurement, and the traditional self-propulsion test method in calm water is further developed and applied to the test in waves. Additionally, the experiment data is post-processed according to ITTC recommended procedures, and the error sources was analyzed.

  Results  According to the ITTC torque and revolution method, the obtained peak power increase of the target cruise ship occurs at wave periods close to 12 s; when the significant wave height is 2 m, the power increase in waves is 554 kW, corresponding to 18.53% of the power consumption in calm water.

  Conclusions  The experimental method presented in this paper is applicable for ships with podded propulsion and can be used for the prediction of a power increase in waves. This provides a reference for a more detailed investigation into the ship's propulsion characteristics in waves and can help expand the design optimization approaches towards more energy-efficient ships.