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Boat fuel consumption

Boat fuel consumption

Did you know: WOT- Wide Open Throttle - the fuel consumption of a turbo-diesel engine in liters per hour is one fifth of its power, that of a gasoline engine is one third of its power.


BOAT FUEL ECONOMY


You often ask us about fuel consumption to be considered for a given boat. If with older engines there might be large differences from one brand to another, now all major engine manufacturers know how to produce good engines, and only the technology causes a real difference in fuel efficiency. Only certain magical advertisements and automakers' software [...] still dare to boast the most spectacular fuel efficiency! But this is another story ...
Below some specific burn rate in liters per hour depending on the technology, at maximum power:


- Petrol engine 4-stroke inboard or outboard 100 HP: 30-38 liters / hour or 34 liters / hour on average. Mémotechnic: petrol engine consumption = 1/3rd of the power. With modern direct injection 2 stroke, take into acount same fuel consumption or even a bit less.
- Inboard Turbo-diesel 100 HP: 18-22 liters / hour is 20 liters / hour on average. Mémotechnic: turbo-diesel engine consumption = 1 / 5th of the power
either a reduction in consumption of about 40% in favor of the turbo-diesel engine.



To apply these fuel burn rate to your boat, at the maximum speed, wide open throttle, just make a rule of three.
For example for a 200 HP inboard engine Turbo Diesel (TIMONIER 745 for example) : 200/5 = 40 liters / hour. For an outboard petrol 200/3 = 66 liters / hour.

At economic cruise speed (2/3rd of top speed) rely on half of the max consumption. For example, OSTREA 700-200 HP : top speed 27-28 knots and 200/5=40 Liters/hour, economical speed, arround 18-20 knots, 40/2=20 Liters/hour.



Finally, remember that because of its combustion cylce, the diesel engine retains the same fuel efficiency at part load use (partial power obtained by less fuel), while the petrol engine efficiency drops sharply when reducing throttle (due to lower compression rate related to the reduced amount of intake air). In other words, the consumption of a diesel engine is declining faster than that of a petrol engine when reducing the power (in cruising for example). Also, all fishermen witness it when trowling: with a diesel, burn rate drop quickly at a very low level.


It is for all these reasons that the speed boats and small sport boats are most often powered by petrol engines and that cruise and fishing boats are usually equipped with diesel engine, more expensive but more efficient in consumption and autonomy.

 

 Comparison O700 INBOARD vs O800 OUTBOARD and comparative outboard 150 hp engines both by French "Moteur Boat Magazine"

You will find bellow some example of consuption :

INBOARDS PERFORMANCES AND CONSUPTION

 

 

The new RC10 is equiped with twin engine NANNI or YANMAR high yield.

 

H2lice Maucourt Hydraquad 19x25 sur OSTREA 700 OCQUETEAU