Engine Loading: The Key to Performance
Understanding engine loading is critical to achieving maximum performance.
To get the necessary loading information it is necessary
to Sea Trial the vessel. These trials are best done
on a nice day with no significant wind or waves at about 80% normal
full load (weight)
with the synchronizer off. There are two ways to measure engine loading.
On gasoline engines or diesel with mechanical governors engine loading
is measured as the Top RPM Wide Open Throttle that
can be achieved.
The top rpm's should be read with either a phototach
or off a quality
digital tachometer.
Accurate readings are critical. More modern diesel
engines are computer controlled and electronically governed.
For
these engines it is necessary to measure the Percent Load
at Wide Open Throttle.
Engine
Loading = Performance
This information allows us to establish where, on the power curve,
the propellers are loading the engines.
Too high an rpm or too low
a percent load indicates that the propellers are not utilizing all
the horse power available.
The vessel will be accelerating slowly
at a perceptibly high rpm and once at speed the engines will seem
to be running fast for the speed.
Too low a top Rpm or too high a
percent load indicated that the propellers are overloading the engines
and the engines are not being allowed to produce the power they are
capable of producing.
In this situation the engines would be running
hot and using too much fuel.
Additionally, idle speed will be unacceptably
high and maneuvering will be difficult because the vessel will have
the
tendency to “jump” when put in gear.
