Regulatory demands on ship designs, such as emission and manoeuvrability requirements, are becoming increasingly stringent, raising the need for advanced methods to predict and assess dynamic propulsion plant behaviour of a new design. At present, model scale experiments and numerical simulations are not able to predict this behaviour in full detail. To fill the resulting knowledge gap, this paper proposes to further develop existing scale model tests into so-called dynamic model basin tests. These tests aim to predict dynamic behaviour of the ship propulsion plant in complex, dynamic environments in more detail, leading to improved propulsion systems and controls and ultimately, lower emissions, lower fuel consumption and increased manoeuvrability.
As early as the 16th century, ship constructors conducted resistance tests by towing scale models through water, thus increasing insight into optimal hull shapes. Later, when combustion engines began superseding sail power, self-propulsion tests were conducted. These tests replace the external towing force by the thrust delivered by the model's own propeller, which usually rotates at a controlled, constant speed. As such, the ship's self-propulsion point can be identified. As a further development, self-propelled ship models were fitted with a rudder assembly, which allowed to conduct manoeuvrability tests; next to fuel consumption and attainable speed, a ship's manoeuvrability is another fundamental design quality. Finally, seakeeping performance of the ship can be predicted by introducing waves in the model basin.
However, the model is often a simplified version of full scale reality, meaning that the behaviour of the model does not completely correspond to that of the actual ship. For instance, one of the main limitations in manoeuvrability and seakeeping tests is the fact that the model propeller speed is (quasi) constant, irrespective of propeller load variations. This implies that dynamic interactions between environment, hull, propeller and machinery are not properly taken into account. At full scale, these interactions do have considerable influence: rough seas impose a fluctuating load on the propeller, possibly increasing the diesel engine's fuel consumption and wear. Moreover, so-called hydrodynamic scale effects occur: incorrectly scaled flow of water around hull and propeller result in incorrect scaling of forces. Despite such shortcomings, however, the aforementioned experiments have been relied upon for many decades to assess ship designs. Simplifications and scale effects can often be compensated for, or even neglected. Manoeuvrability tests, for instance, have shown to produce useful predictions (Hooft, 1994).
