One of the world’s most advanced survey vessels features bow and stern thrusters powered by Control Techniques modular AC drives to achieve position accuracy of  ± one metre.

The Poseidon is the second vessel developed for seabed surveys by owners Neptune Survey Expedition, an Icelandic company started in 2008. A 69-metre long, 11.7-metre wide former fishing trawler, the vessel has been fitted with the latest surveying technology, including multibeam sonar and is also equipped with a remote operated underwater vehicle (ROV).

Its remarkable positional accuracy is attained with the Norwegian Konsberg navigational / positioning system that provides dynamic position control to achieve the ‘DP1+’ certification required.  This ensures position control to a metre in any direction.  The dynamic system uses satellite navigation to fix its position and the control system uses a combination of the propellers, rudder, and variable speed / variable pitch bow and stern thrusters to maintain this position.  Ultrasound is additionally used to provide position control of the ROV.

Two Unidrive SP9 drives were supplied to control the 450kW bow and stern thrusters, used to maintain accurate lateral positioning of the vessel.  The drives are controlled by a simple 4-20ma speed control signal from the Konsberg +1 navigation PLC that combines variable-speed thrusters control with hydraulic pitch control to give the required positional accuracy.

The thrusters are tunnel mounted in the bow and stern, with their motors direct mounted on top of the screws with no gearbox, and are highly dynamic, being capable of decelerating from full speed (1300rpm) in just a few seconds, whilst the pitch control is simultaneously varying as needed.  The combination of both speed and pitch control allows very fine positional adjustment.>>>>>>>>