Also, Kobelco Marine Engineering Co., Ltd. introduced the latest trend of stern tube sealing device. Kawasaki Heavy Industries Ltd. introduced a generalization about water jet propulsive system and the latest result of research about inlet duct which gives considerable effect for its performance in relation with the trend of high speed.

In addition, Nippon Yakin Kogyo Co.. Ltd. introduced special feature for strength, anticorrosion and the cost about stainless steel shafts which have many deliveries as shafting device of high speed ships.

Regarding labor saving at the work site, Harada Corporation introduced the installation method of stern tube bearing by synthetic resin improving working efficiency instead of traditional force fit of stern tube bearing.

As for the topic, Hitachi Zosen Corporation constructed a special work boat equipped with Electric Propulsion System (Fig 6.1). The ship was delivered in FEB 1998 and engaged in special operation such as laying work of submarine cable.

The particulars are listed in the below;

Lpp x B x D : About 62m x 16.5m x 7.5m

Propulsive Electric: Squirrel-cage induction motor

Motor　: 1400kW x 750rpm x 2 sets

Propeller　: CPP Type 360° rotating propeller

Maneuvering System: Individual control and DPS control (Automatic maneuvering and Joystick Control)

Fig. 6.1 CPP Type 360° Rotating Propeller

Electric power source for propulsion motor of this ship is given by four (4) exclusive use generators for thruster. As the frequency of electric power source is changeable by controlling the speed of diesel engine for power generators, which results in the availability of speed control of propulsion motor, the reduction of power consumption for running at low load and the decrease of noise in the water can be realized.

Furthermore, it is possible to operate the propeller running at very slow speed by using the slipping function of the clutch incorporated, in order to obtain very fine maneuvering of the ship.

Kamome Propeller Co., Ltd. manufactured CPP incorporated with reduction gears (Fig 6.2) for 11,000GT R0/R0 Cargo Ship. The particulars are listed in the below;

Lpp x B x D : 150m x 24m x 15.8m

Main engine : Diesel engine

21,600PS x 430rpm

Propeller　: 4 blades x 5,400mm

Controllable Pitch Propeller

Maneuvering System: Individual control and Joystick control

Fig. 6.2 CPP Incorporated with Reduction Gears

In this system, the oil for reduction gears and CPP can be used in common and it is possible to unify the control of oil by making oil distribution box of CPP is assembled in reduction gears. By this, sump tank and gravity tank for the both systems can be used in common and the reduction of tank and the number of piping lines are possible at the same time.

Furthermore, servo cylinder can be simplified and installation will be easy as oil distribution box is assembled in reduction gears.

　

Reference:

　

1)　60th MESJ Proceedings of Technical Paper (MAY '98)

　

[Takashi ODAGIRI]

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