SHIP PROPULSION

Ship (Marine) propulsion Mechanism used to move a ship across water

(engine turning a propeller)

Choice of a suitable powerplant depends on:– size of the ship – speed (type of cargo)– length, duration of voyage– cost (operational expenses)– fuel

Diesel Engine

In 1892 Rudolph Diesel invented the compression ignition engine

The most widely used propulsion

Two-stroke (large engines) Four-stroke (auxiliary e.)

Diesel Engine

PROS: – most efficient prime

mover– lower fuel

consumption – less bunker space

CONS:– more expensive to

build and maintain– more noise and

vibration– heavier

Steam Turbine Marine steam turbine was

developed by Sir Charles Algernon Parsons

Low noise, low weight, low maintenance costs, more space obtained (power /weight ratio raised)

BUT higher fuel consumption

Steam Turbine Most new-build ships with

steam turbines are specialist vessels such as nuclear-powered vessels, and certain merchant vessels (LNG, coal carriers) where cargo can be used as bunker fuel.

Diesel electric drive Large cruiser, tankers,

ferries, ro-ro passenger ships and LNG carriers

PRINCIPLE 1. diesel engine

connected to a generator 2. Generators drive

electric motors 3. Electric motors drive

the shaft

Turbo-electric drive PRINCIPLE 1.Turbines generate

mechanical energy and drive generators

Generators convert mechanical into electrical energy and drive motors

Motors convert back the electrical into mechanical energy and drive the propeller shaft

Gas turbine A compressor draws in

and compresses atmospheric air.

A combustion system where fuel is injected, mixed with compressed air and burned.

Power turbine to the shaft. Poor thermal efficiency at

low power.

Nuclear propulsion

Submarines, navy ships (air-craft carriers), icebreakers.