Recommendation
Continuous operation without limitations is al-
lowed only within the area limited by lines 4, 5,
7 and 3 of the load diagram, except on low load
operation for CP propeller plants mentioned in the
previous section.
The area between lines 4 and 1 is available for
operation in shallow waters, heavy weather and
during acceleration, i.e. for nonsteady operation
without any strict time limitation.
After some time in operation, the ship’s hull and
propeller will be fouled, resulting in heavier run-
ning of the propeller, i.e. the propeller curve will
move to the left from line 6 towards line 2, and
extra power is required for propulsion in order to
keep the ship’s speed.
In calm weather conditions, the extent of heavy
running of the propeller will indicate the need for
cleaning the hull and possibly polishing the pro-
peller.
Once the specified MCR has been chosen, the
capacities of the auxiliary equipment will be
adapted to the specified MCR, and the turbo-
charger specification and the compression ratio
will be selected.
If the specified MCR is to be increased later on,
this may involve a change of the pump and cooler
capacities, change of the fuel valve nozzles, ad-
justing of the cylinder liner cooling, as well as
rematching of the turbocharger or even a change
to a larger size of turbocharger. In some cases it
can also require larger dimensions of the piping
systems.
It is therefore of utmost importance to consider,
already at the project stage, if the specification
should be prepared for a later power increase.
This is to be indicated in the Extent of Delivery.
Line 5:
Represents the maximum mean effective pres-
sure level (mep), which can be accepted for con-
tinuous operation.
Line 6:
Propeller curve, clean hull and calm weather – light
running, used for propeller layout/design.
Line 7:
Represents the maximum power for continuous
operation.
Limits for overload operation
The overload service range is limited as follows:
Line 8:
Represents the overload operation limitations.
The area between lines 4, 5, 7 and the heavy
dashed line 8 is available for overload running for
limited periods only (1 hour per 12 hours).
Line 9:
Speed limit at sea trial.
Limits for low load running
As the fuel injection for ME engines is automati-
cally controlled over the entire power range, the
engine is able to operate down to around 15-20%
of the nominal L
1
speed, whereas for MC/MC-C
engines it is around 20-25% (electronic governor).
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