Measurements with submerged bodies are performed on originals or copies in original size and scale models. The range of test objects extends from submersibles such as ROVs and AUVs to submarines and special investigations of marine life and divers.

To determine the motion behaviour of underwater vehicles in the vertical and horizontal plane, and also for resistance and propulsion tests as well as wake measurements, the SUBPMM (Submarine-Planar-Motion- Mechanism) system is used. What is special about this system is that the measuring points of the forces are placed within the model and hence the influences of the towing device can be eliminated. The system is adaptable for model sizes from 1 to 6m and depths of 0.5 to 2.5m. For driving the models, enclosed motor dynamometer modules are used with different sizes to choose from.

For the determination of the motion behaviour of underwater vehicles, the simple drag motion of the model can be superimposed with an additional level of movement with the SUBPMM system. In addition, the angle of attack of the model as well as the control arms can be varied. Thus, it is possible to determine the coefficients for the equations of motion.

The SUBPMM system is also used for resistance and propulsion tests. For wake measurements a probe with pressure sensors is used which can be adjusted automatically.

In the R&D projects, “Scale Effects in Determining the Manoeuvring Behaviour of Underwater Vessels by Model Testing” [3], “Correlation of Resistance of Submerged Bodies” [1], “Interference Phenomena in Substructures of Submerged Bodies” [2] and “Influence of the Reynolds Number carried out in the Thrust Deduction Fraction”[4] Geosim-tests and calculations for underwater vessels for motion behaviour, resistance and interference phenomena were executed. The results of these studies are incorporated into the correlation for full scale predictions.

In heavy seas, especially in conjunction with high ship speeds, due to the heave and pitch motions of the ship, the bow can come out of the water. When re-immersing and exceeding a critical relative vertical velocity at the hull surface, enormous pressures and forces can occur which can cause damage to the ship due to these impacts.

To investigate this problem experimentally, a hydraulic slamming system was developed in the SVA. With this system, pitching, heaving and coupled movements can be introduced with a frequency of up to 2.0 Hz and an amplitude of up to 10 cm on model ships. It can test models with a length of 5.5 m and a moving mass of 500 kg. By measuring pressure variations in the kHz range on up to 30 measurement points, local peak pressures can be identified.

With an adjustable blade hub, the dynamic adjustment of ptich during testing is possible, for example, for stopping manoeuvres. The adjustable blade hub achieves the change of blade pitch with a multiphase motor with two limit switches built in which switch off the engine at ± 30° adjustment. The average pitch is marked on the inner hub. The angle is measured with a potentiometer. The hub is mounted on a carbon ring. The control data and the values of the potentiometers are transmitted via a slip ring assembly.

For measuring the forces on VSP (Voith Schneider Propeller) drives, special measuring balances have been developed which, in comparison with the conventional VSP balances, enable the measurement of thrust, two lateral forces, and the drive torque. The VSP balances can be used in ship models, in the towing tank, and in the cavitation tunnel.

Technical Specifications
Measurement of
Thrust	✓
Lateral Forces	2
Drive torque	✓
Torque	✓
Max. force component [N]	200
Max. torque [Nm]	8