Computer holds ship in position without anchor

8:03am Wednesday 23rd July 2008

Next year when the 93,000 tons cruise ship Norwegian Jade calls here in all probability she will come into the Carrick Roads and remain on dynamic positioning (DP) for the duration of her cruise call.

DP is a complex computer controlled system whereby thrusters, main engines, generators and navigation equipment are all used to keep the ship in one position without the vessel having to anchor.

The ship can be angled across the wind and swell conditions to provide a lee for the passenger tenders, which is called weathervaning.

External forces on the hull can be detected using position reference sensors, motion sensors and wind sensors linked in with the gyro compass and global positioning system all of which tell the computer information relating to the ship's position and the direction and magnitude of environmental factors affecting the vessel.

In layman's terms the computer makes calculations to determine the amount of engine power and thruster power the keep the vessel on station.

When the Norwegian Jade sailed from the bay last week the ship was turned on DP and with the pivot point of the ship placed amidships the 294-metre long vessel turned through 180 degrees only moving 1.7 metres away from the intended turning position.

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