HSVA performed manoeuvring model tests outdoor with a freely moving ship model in December 2018. In this exceptional case it was important to be able to see the whole manoeuvres being executed. The HSVA standard manoeuvring method using the Computerized Planar Motion Carriage (CPMC) yields accurate results in a very reliable manner, but does not enable to actually see the complete manoeuvre being executed by the models in the towing tank having a limited width, particularly when large diameter turning circles need to be executed.
A remote controlled HSVA ship model executing a complete turning circle in outdoor tests.
The HSVA used this unique opportunity to perform the standard procedure with indoor zigzag tests and to compare the turning circles based on these with the turning circles performed directly outdoors. These results show a very good correlation, even though the outdoor tests were carried out in typical northern German winter weather conditions on the target test day. Thus no delay was caused by potentially unfavourable weather.
A suitable location without much wind, waves and current was used, and hardware to measure the ship motions autonomously was installed in the free manoeuvring ship model, steered and driven with the HSVA ship model control and propulsion system (SAS). For best reliability of the measurements the path of the model was measured using the tracking system differential GNSS, using a rover on board of the model and the base station on-shore nearby for very good position accuracy. For all data transfer a wireless connection was used. The accuracy reached this way is in the order of few centimetres, which is totally sufficient for the purpose.
The test campaign showed that good results can be obtained with outdoor tests, which also provide an excellent opportunity to demonstrate and visualize ship rudder manoeuvres being executed, from straightforward turning circles to complicated harbour manoeuvres.