The fuel consumption tests were conducted on the 11.5 metre Westpark to Auckland City ferry “Belaire”. This vessel is a mono hull ferry powered by a Scania V8 diesel rated at 428 KW (582 HP) at 2100 rpm. The engine is approximately four years old and had 4600 service hours. The engine has been regularly serviced at the engine manufacturer’s recommended intervals.

On 12 February 2009 an initial fuel consumption test was done with the vessel fully fuelled and watered and with two persons on board. Fuel consumption was measured at different engine rpm from 800 rpm through to maximum rpm (2090 rpm indicated) in 100 rpm steps.

These fuel consumption tests were again repeated on the 17 March 2009 with the vessel again fully fuelled and watered along with the same two persons on board. Sea conditions were similar to those on the original test day (calm with wind around 10 knots).

At the time of the second test “Fuel Doctor” Fuel Conditioner had been added to the fuel tanks as follows:

  • Engine hours with conditioner added 135.8
  • Fuel added over this period 5943.16 litres
  • Volume of Fuel Doctor Conditioner added over this period 4.1 litres

From the Test Report attached it can be seen that at the same indicated (analog rpm guage) rpm over and above 1300 rpm the fuel consumption dropped from the original test results where no Fuel Doctor Conditioner had been added to the fuel.

Varying % difference figures at the indicated rpm from 800 to 2000 rpm could be explained by the fact that on an analog rpm guage it would be extremely difficult to have precisely the same rpm set on the engine for both tests.

At the maximum indicated rpm of 2090 for both tests the engine was limited in achieving any further rpm by its “variable speed governor” that prevents the engine when loaded from exceeding 2100 rpm (true, not indicated rpm). At this maximum speed a 5.08% reduction in fuel burn was recorded.

These tests indicate that a fuel saving of up to 5.08% is achievable on a diesel engine operating in a commercial marine environment. No mechanical or other adjustments had been done on the test engine over this testing period other than a routine service of oil, oil filters and fuel filters.

The tests were carried out on DZL fuel test equipment that had on manufacture an accuracy of 99.9% over its operating range of 4 LPH to around 300 LPH.

Yours sincerely

John M Menzies

Dieselcraft Evaluations

Letter From Dieselcraft Evaluations – Download Word DOC

Marine Performace Check – Download PDF FILE

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