Operation Manual

8
Diesel fuel flow sensor kit Installation and Operation Manual
NAVMAN
As with all measurements, you will get no
meaningful data if you do not have accurate
instruments. Once you have accurate fuel
consumption, boat speed and engine speed
figures, then the true power of the diesel flow
sensors can be used.
Boats
All boats are different - even consecutive boats
off a production line can be quite different
in performance. So there is no real ‘generic’
data that can be applied to your particular
boat/engine/propeller combination.
Fuel Consumption
The simplest set of information you can get
from the diesel flow sensors is fuel consumption
- US Gallons per nautical mile or Litres per
mile. This figure will depend on many factors
- the condition of the hull (clean or fouled), the
loading and trim of the boat, wave and wind
conditions. Over time you will get an idea as to
how different conditions affect the performance
of your boat.
Engine RPM
Engine revolutions per minute (RPM) is the
single most important item in any instrument
package, as it is the base line against which
such things as boat speed, fuel usage, and
propeller efficiency are measured - if your base
line is inaccurate all the readings using it are
inaccurate. Accuracy is all important.
Many rev counters supplied with engines are
not very accurate, and should be recalibrated
after they have been installed in your vessel.
Navman have designed a tachometer as part
of the diesel flow kit. The tachometer measures
engine RPM digitally, with timing derived from
the highly accurate crystal running the whole
system. This digital tachometer never needs
calibrating.
Boat Speed
Check that your boat speed instrument is
reading correctly. If necessary, recalibrate
boat speed as described in the instrument’s
operation manual.
Remember that there are two distinct ways
to describe the movement of a boat - speed
through the water, and speed over the ground.
In still water with no tides or currents then
these two speeds produce the same reading;
otherwise they are quite different, and you need
to be sure you are using the correct one:
Speed through the water is usually read
from a paddle-wheel sensor. Use this
speed to check your boat’s performance
and fuel consumption.
Speed over ground is usually read from
a GPS receiver. Use this speed to work
out maximum range, fuel reserve and
time of arrival.
2 Understanding boat performance data