Maneuvring Experiments of High Speed Twin Screw Container Ship

Abstract

With a receot demand for increase in ship size and speed, multi screw-twin or triple-has been adopted in many cases of fine ships such as container ships and car ferries. In a single screw fine hull form where good course stability and turning ability can be obtained by installing a suitable size of rudder, we have not given so much importance to the matter of manoeuvrability. In a multi screw fine hull form, we are allowed to select the number and shape of rudders which have much effect on maneuvrability, especially course stability, while it is necessary to design the around-rudder-part not to cause reduction in propulsive performance without unnecessary rise-up in building cost. We, Kawasaki Heavy Industries, Ltd., built and are building high speed car ferries and high speed container ships equipped with twin screw. In the former ships, to develop high manoeuvrability, twin rudder was installed taking account of their speciality of frequent operation in port. In the latter case, in designing the container ship treated in this paper, whether to select single rudder or twin rudder was raised as an important problem for study because of its different function from the former's. This container ship is now placed on the New York line. (Capacity: 2,068 of 20 feet containers Engine: 2 sets of 40,000 BHP engine Service speed: 26 knots) To obtain a solution of the problem, we conducted, at an initial design stage of the ship, a manoeuvring model test at our Kakogawa Exprimental Basin with full load condition. From an analysis of the model test result and expected surrounding conditions of the ship in its operation, we decided to adopt a single rudder and built a twin screw container ship with a single rudder. Its sea trial result was satisfactory, and it is favourably rcceived by crews as a ship of good manoeuvrability. In this paper, we state the result of the said model test carried out in process of deciding the stern arrangement including the number of rudders and the rudder area of the ship, and also that of the actual ship test conducted after delivery.