PERFORMANCE OF SHIPS IN ACTUAL SEAS
Accurate evaluation of required power toward ship speed and fuel consumption performance in actual seas with winds and waves enables highly efficient operation of ships.
This group is conducting research and development on design technology and energy-saving operation technology for ships with excellent propulsive efficiency in actual seas, and is aiming to improve the ship performance from both aspects of sectors of shipbuilding and shipping. In addition, we are tackling on solving technical issues about international regulations on GHG emissions from ships.
(◎: Head of the Group)
VESTA is a ship performance simulator that estimates ship speed reduction and fuel consumption in actual seas with high accuracy based on the prediction method of added resistance in waves. It has acquired the program certification from ClassNK (Nippon Kaiji Kyokai) for the judgment function of the minimum propulsion power rule in Energy Efficiency Design Index (EEDI).
Ships in actual seas are affected by winds and waves, the resistance increases due to the external forces, and propulsive efficiency is reduced by changes of the flow field around propeller and its load condition. STEP has the effect of reducing the added resistance due to waves, which is the main external force that acts on the hull, and contributes to the reduction of GHG emissoins from ships.
COVE is one of energy saving devices which has a bow shape with concaved frame lines above the water surface of static swell up of bow wave, and it has an energy saving effect of about 10% in actual seas condition (wave height 3 m).
As a method to improve energy efficiency during ship operation, weather routing and deceleration operation of ships are known. In addition, attention is also being focused on techniques for improving resistance and propulsion performance by adjusting the trim of the ships according to the load condition.
For the use of Northen Sea Route for ships, which is expected as a measure against global warming, it is important to evaluate ice conditions and speed and fuel efficiency of ships going on the ice sea. We are working to improve the accuracy of evaluation methods for speed and fuel consumption by utilizing Ice Tank and estimation program that make use of our knowledge accumulated so far.