Classification of Ships as per Propulsion Plants
M.V. – Motor Vessel
(i) Diesel Engine Propulsion
1. 2-stroke Diesel Engine – Low/Slow Speed (< 300 rpm)
The propeller shaft is directly connected to the main engine.
Constant-pitch propellers are used.
The speed of the ship is controlled by adjusting the speed of the main engine.
Reversing is achieved by changing the rotation direction of the main engine.
2. 4-stroke Diesel Engine – Medium (300-900 rpm)/High Speed (>900 rpm)
The propeller shaft is connected to the main engine through a gearbox.
Controllable Pitch Propellers (CPP) are used, and the ship’s speed is controlled by changing the pitch of the propellers.
Reversing is achieved by changing the pitch of the CPP.
(ii) 2-stroke Dual Fuel Engine – runs on both HFO & LNG
Cargo ‘Boil Off’ Gas is used as the second fuel in LNG Carriers.
C. Diesel Electric Propulsion
Electrical motors are used for propulsion, powered by diesel engines (generators).
The propeller shaft is connected to the electrical motor.
Ship speed and reversing are controlled by adjusting the motor’s speed.
Reversing is controlled by rotating the propeller assembly.
S.S. – Steam Ship
(i) Reciprocating Steam Engine
(ii) Steam Turbines
Steam turbines are used in nuclear-powered naval ships, where a nuclear reactor heats water to generate steam that drives the turbines.
Dual Fuel Turbines – Cargo ‘Boil off’ gas is used as fuel for the boilers, which provide steam for the turbines.
Gas turbines are used as the main engine for propulsion in naval ships and some passenger ships.
Main Engine Plants & Supporting Systems:
– Diesel Engine Working Principle (MEACS IV Unit I)
– Starting Air System
– Fuel Oil System (Supply and Injection)
– Scavenging & Exhaust Gas System
– Lubrication Oil System (Bearings and Cylinder Lubrication)
– Cooling Water System
– Control Devices (Governors, Reversing)
– Operations – Standby, Starting, Reversing, Maneuvering, Full speed