The winches were controlled based on the required driving force. By using two winches, the force vector can move in any direction between them. This accounts for diversions in course, speed and unexpected heel angles. As far as we know this set-up is unique in the world.
Applications for wind-assisted ships in this same test set-up could be: • The combined (steady) heel and (dynamic) roll and the influence of sails in this
• The course keeping ability in stern quartering wind and waves (probably with very little propeller flow over the rudders and large roll and yaw wave excitation)
• The possibility to meet zig-zag IMO requirements.
After a little tuning, the PANSHIP simulations corresponded very well with
Figure 2: Added resistance
the test results. The overall calculations matrix yielded the added resistance as a function of wave height, relative direction, period, ship speed, heel angle and various boat settings. This is a much more detailed description compared to the typical empirical calculation with only two or so parameters. The variations within the more extensive parameter space can in fact be very relevant as shown in Figure 2. Although specific numbers will be shared only after the race, it can clearly be seen
that the added resistance varies significant- ly with heading (green versus red line).
Certainly, MARIN was able to provide valuable information to team AkzoNobel to calibrate their performance in calm water and to make better routing decisions to allow for the performance degradation in seas. At the same time, the project has yielded spin-offs with lessons learnt and an improved test set-up that can also be used for wind-assisted vessels.
VO65 model in waves in the basin
Example of wave profile calculated with ReFRESCO
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