Overseas Shipholding Group (OSG) has contracted Raytheon Anschütz to retrofit the newly developed Anschütz NautoPilot 5300 autopilot system onboard its fleet of oil tankers, replacing the existing systems, with the aim of improving energy efficiency.

The new autopilot features an integrated ECO-Mode, which helps to optimise rudder movements by automatically adapting to the current sea-state and weather.

Instead of keeping a heading with frequent rudder actions with high amplitudes, the rudder's sensitivity to periodical yawing movements caused by roll and pitch is reduced and less rudder action is required, which leads to lower levels of speed reduction and thus less fuel consumption.

The first of the new autopilot systems was installed onboard Overseas Fran in October 2011, and was used for a voyage from Skagen to New York.

To investigate the actual effect, the heading and rudder plot of this voyage was compared with the results of the last voyage on the same route with the old autopilot system, under similar weather conditions during both voyages.

"We can see on our print-out that rudder movement is more economic and gentle with the new autopilot system," said Capt Dmitry Shatrov, Master of the Overseas Fran.

"The newly installed autopilot system has a user-friendly interface in which you can easily adjust autopilot functionality in the prevailing circumstances, weather condition and required steering accuracy, so that we can navigate the vessel more gently and economically, taking into consideration fuel savings and safety."

The ECO-Mode is supported by a new integrated heading and rudder plotter, which provides a graphical indication of heading changes and the resulting rudder angles.

This graphical display indicates the steering performance of the vessel due to the effects of changes to parameter settings such as rudder, counter rudder and yawing. This can help the operator to optimise steering performance, to further minimise rudder action and increase fuel efficiency.

"OSG are undertaking great efforts to increase energy efficiency onboard of their ships. The choice of our new adaptive autopilot system was influenced by considerations of saving fuel and thus reducing emissions," says Olav Denker, product manager at Raytheon Anschütz.

"With OSG, we have now had the chance to prove positive effects of NP 5000 on steering performance and fuel consumption in practice for the first time."

Source: The Digital Ship