Instationary Captive Model Tests

The Seakeeping and Manoeuvring Basin of MARIN measures 170 m X 40 m X 5 m and is equipped with an X-Y carriage and turntable. The movements of the carriage are individually controlled and circular motions, oscillating and user defined paths can be followed. The dimensions of the basin and the flexibility of the user defined paths make it possible to perform a wide variety of captive model tests. One path can include multiple speeds, drift angles and rotation rates. Alternativelty, a whole range of conditions can be tested by adjusting a parameter continuously. This way, multiple PMM oscillations can for example be replaced with one spiral or 8 shaped track in which a wide range of rotation rates is tested.

A model of the 5415 US Combatant is used to investiage the full capability of captive in the Seakeeping and Manoeuvring Basin. In addition, regular PMM and CMT model tests have been executed with the same model and in the configuration to make a one-on-one comparison. A good agreement is observed between all types of tests and consequently the instationary tests are an interesting alternative.

This method provides MARIN with an efficient way to obtained almost full knowledge of the hydro dynamical forces ib a vessel which can be used to define a mathematical model. Such a mathematical model can be used to perform simulations of zigzag and turning circle manoeuvres or simulations in a fast time or real time ( full mission bridge) simulator.