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Measurement & control engineering

After the model has been made, it is aligned and the appendages are attached. Becayse model vessels need an engine, a steering system and various types of measurement equipment. We design, build and maintain the measurement equipment required in model testing. Finally the model is given a unique number and is then ready for use in further investigations.

Using laser equipment, we attach the frame and waterlines. This enables us to see the wave pattern around the ship during model trials. Further, the water lines – also known as draught lines – are important in ensuring the ship is precisely at the right depth with the help of extra ballast.

Appendages

The appendages are the model components that are not considered part of the hull, but are attached to or in the hull. For example, the rudders, bow tubes, shaft tubes and stabilising fins. The appendages depend on the ship type. Simple models have a rudder and a tube for the propeller drive shaft. A model of a cruise ship or naval vessel has shaft carriers, bow tubes and stabilising fins.

Construction

For wave and wind trials, the model comprises the ship’s hull and appendages as well as the superstructure that includes the bridge and decks. Offshore platforms, such as drilling platforms have, for example, mooring and anchoring installations, drilling rigs, buoys and jackets.

Sensors

Sensors are used to measure forces. They comprise 4 gauges that are switched and connected to a constant power supply. A gauge is a small piece of foil with a very thin metal thread, the diameter of which changes as it gets longer or shorter. By this means, the electrical resistance changes in the gauge and thereby also the output signal. These sensors are built into the model to make the measurements.

For each situation and for each force (for example, stretching, shrinking and torsion) a new sensor is developed. Sometimes, the sensor must be extremely small to fit in an oil hose or placed in the propeller shaft of a ship model. Sometimes, a model is sawn into sections in order to measure the forces in different ship components.

Control systems

Control systems are need for engines and steering systems in the model to ensure the engines do exactly as required. This means that a regulator is needed to steer the engine and software to determine what is required. The equipment operates together and is connected via a junction box to the central control system. This ensures that the model sails at a constant speed, that it is steered back on course if the waves send it off course, but also stops the model from wandering because the foils under the water start to move.

Hexapod

The hexapod has 6 feet which enable a model to make all types of movements. For instance, we can investigate whether water in swimming pool on a luxury yacht goes over the side when there are high waves. Our Fast Small Ship Simulator has a hexapod that gives you the feeling of bouncing over waves at high speed.

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Did you know

a force measured with a sensor is expressed in microstrain: 1 microstrain = 0.000001 m?

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