Propeller system
54
Propeller suitability with reference to ship resistance and driving power
Propulsion engine, ship’s hull and the propeller form a system, whose individual components interact.
The propulsion engine provides the driving power, the ship’s hull accepts the driving power and the
propeller transmits this driving power.
Therefore the propeller must be suited to this system in terms of its design, diameter and pitch.
Correctly adjusted propeller for the test drive
The propeller must be selected so that during the
test drive of the new ship an engine rpm of
2320−2350 rpm can be reached
(Operating point Ã).
The ship must thereby be loaded as follows:
− Equipment on board
− Fuel tanks filled
− Water tanks filled
À Engine power curve
Á Propulsion resistance curve
 Speed/power reduction curve
à Operating point, new condition (max. rpm is
equivalent to 102 % of rated speed)
Correctly adjusted propeller for normal
operation
If 102% of the rated speed was reached during the
test drive, this ensures that when the propulsion
resistance increases (due to growth on hull under
waterline) the rated speed of the engine will not go
below 2300 rpm.
Ä Operating point for normal operation (max. rpm
is equivalent to 100 % of the rated speed)
0
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Rpmin%
Powerin%
2
3
4
1
0
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Speedin%
Powerin%
5
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