Marine Installation Manual
2021-08
2-1
2 Engine Power and Speed
2.1 Introduction to power and speed
X72DF
2
Engine Power and Speed
Selecting a suitable main engine to meet the power demands of a given project in
-
volves proper tuning with respect to load range and influence of operating condi
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tions which are likely to prevail throughout the entire life of the ship. This
chapter explains the main principles in selecting a WinGD 2-stroke marine diesel
and gas engine.
2.1
Introduction to power and speed
It is critical that a ship’s propulsion system correctly matches the main engine
characteristics to ensure reliable operation under a variety of conditions in
-
cluding design and off-design conditions. The sections below outline the specifics
to aid in this process.
2.2
Engine rating field
The rating field shown in
is the area of selectable engine design power
and engine design speed. In this area, the Contracted Maximum Continuous
Rating (CMCR) of an engine can be positioned individually to give the desired
combination of propulsive power and rotational speed. Engines within this
layout field are tuned for maximum firing pressure and best efficiency at the se
-
lected rating.
Figure 2
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1 Rating field for the X72DF
SM-0165
50
60
70
80
90
100
60
70
80
90
100
Engine speed
[%]
Engine power
[%]
The contracted maximum continuous rating (Rx) may be
freely positioned within the rating field for that engine
Rating line
fulfilling a ship’s
power requirement
for a constant speed
Nominal propeller characteristic (1)
Nominal propeller characteristic (2)
R1
R2
R3
R4
Rx1
Rx2
