SHIP PROPULSION

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SHIP PROPULSION
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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

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Diesel Engine

• In 1892 Rudolph Diesel invented the compression
  ignition engine
• The most widely used propulsion
• Two-stroke (large engines)
• Four-stroke (auxiliary e.)

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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

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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

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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.
  

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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

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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

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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.

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Nuclear propulsion

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