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Enumerate the propeller safety margins in relation to the chief engineer?

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  • Enumerate the propeller safety margins in relation to the chief engineer?

    Enumerate the propeller safety margins in relation to the chief engineer?

  • #2
    o PD- propeller design point (obtained theoretically in experimental tanks)
    o SEA MARGIN
    • Over a period, hull and propeller become fouled, and hence resistance increase demanding more power for same speed.
    • Also when weather is bad, resistance increases further
    • Hence for determining engine power, it is normal to give 15% allowance as sea margin

    o ENGINE MARGIN:
    • Engine margin is 10 – 15% and is added to operational margin of engine

    Shaft Generator Margin
    • Is required if shaft generator is present and additional margin kept for shaft power

    o LIGHT RUNNING MARGIN
    • Over a period hull and propeller is fouled, and hence power will be required to maintain same speed
    • This margin is 5 – 6% when deciding power and speed characteristics of the engine

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