3.3.2
Fixed pitch propeller (FPP)
3.3.2.1
Continuous service rating
Point A (
) shows the power and speed of a ship that operates at contractual speed in
calm seas with a new clean hull and propeller. A power / speed combination at point D is necessary
for the same ship at the same speed during service conditions with aged hull and average weather.
Point D is then the CSR point.
3.3.2.2
Engine margin / operational margin
Most owners specify the contractual loaded service speed of the ship at 85% to 90% of the contract
maximum continuous rating (CMCR). The remaining 10% to 15% of power can be used to catch
up with changes in schedules or for the timing of dry-dock intervals. This margin is usually
subtracted from the CMCR. Thus, to get the 100% power line, you divide the power at point D by
between 0.85 to 0.90.
3.3.2.3
Load range limits
Fig 3-4
Schematic diagram - Relation Speed/Power (FPP)
110
100
95
90
80
70
60
50
40
65
70
80
90
95
104
100
108
Engine power
[% Rx]
Engine speed
[% Rx]
Propeller curve
without SM
EM/OM
SM
4
3
1
2
5
6
CMCR (Rx)
B
A
D
Engine load range
Constant torque
Nominal propeller characteristic
LR
00117
When the engine has the best values at CMCR (R
X
), the limits that follow give the load range of
the engine:
•
Line 1 is a constant MEP or torque line through CMCR from 100% speed and power down
to 95% speed and power.
X72-B
AA00-0000-00AAA-042B-A
Operation Manual
The relation between engine and propeller
Winterthur Gas & Diesel Ltd.
- 69 -
Issue 003 2021-12
