Marine Installation Manual
2021-08
2-7
2 Engine Power and Speed
2.5 Power range limits
X72DF
Line 5
Engine Operation
Power Limit
Admissible power limit for engine operation. The line is separated by the break
-
.
Line 6
Transient Operation
Power Limit
Maximum power limit for transient operation. The line is separated by the break
-
.
Line 7
Nominal Engine
Characteristic
Nominal engine characteristic curve that passes through the CMCR point is de
-
fined by the propeller law:
Formula 2
-
3
Line 8
Light Running
Propeller Curve
Propeller curve with a light running margin (typically between 4% and 7 %).
The curve is defined by the propeller law with a constant, governed by the se
-
lected light running margin (
).
Formula 2
-
4
where:
P
LR
........... = propeller power at selected light running margin [kW]
P
CMCR
....... = CMCR engine power [kW]
n
............... = selected engine speed [rpm]
n
CMCR
....... = CMCR engine speed [rpm]
C
.............. = constant
LR
............ = light running margin [%]
Line 9
CMCR Power
Maximum power for continuous operation.
Line 13
110 % CMCR Power
Constant power overload limit, available for testbed operation and emergency
operation according to SOLAS Regulation II-1/3.6.
Engine Operation
Power Range
Line 5, Line 1 and Line 9 form the curve for the engine’s operation power range
limit, as defined by
. Each component is governed by different
coefficients (see
).
3
CMCR
CMCR
P
n
P
n
æ
ö÷
ç
÷
ç
=
÷
ç
÷÷
çè
ø
3
L R
CMCR
CMCR
P
n
C
P
n
æ
ö÷
ç
÷
ç
= ⋅
÷
ç
÷÷
çè
ø
3
1
1
C
LR
=
+
æ
ö÷
ç
÷
ç
÷
ç
÷
çè
ø