Wave basin

The behaviour of the vessel has been tested in a wave basin.
The tests include:
- Test in regular waves.
- Test in irregular wave (same as above) combined with wind.
- Test in irregular waves: 3 sea states have been tested. The significant wave height are: 2,5 m, 5,5 m and 13,5 m.

The purposes of the tests were to verify the theoretical model, to verify that no non expected non-linearity or interaction between motions exist, to highlight the effects of the wind mills on the vessel motion and finally to investigate the effect of the vessel motion on the power output of the mills.
It was also decided that the wind velocity should be the most frequent one, which corresponds to the maximum forces on the turbines. The reference wind velocity was about 10 m/sec with turbulence intensity in the range of 6%-10%.
The turbine model was then tuned to achieve the correct drag force, such that effect on the vessel was correctly represented. As a consequence the power output could not be correct. But it is assumed that the relative variations are representative for the real behaviour of the turbines.
The scale was 1:64,29. Froude scale method is used.


The first part of the test was focused on the comparison of the behaviour of the vessel in the two possible versions: with and without skirts.
It appears that the motion in heave was much better for the with skirt version, while for pitch the without version gives better results. Since the most critical motion for the turbines is pitch, it was decided to proceed further without the skirt.

All tests have been performed successfully.