OK Here's a real beginners question and I don't expect an exact answer just
a reasonable guess or estimate.
I'm looking at a 27 bayliner, 1983, Volvo penta 260 hp
Supposed to cruise about 20.
What should a reasonable expectation for fuel usage be ?
By the hour or by the mile. info sets hull speed @ about 27, so 20 should be
a little fast as far a rpms go, If I drop back to 17-18 mph that should
increase mileage. Just guessing, I haven't ever owned a bout of this size,
but I am looking forward to some cruising
Thanks for any suggestions and help

Kickstart

kickstart wrote:
OK Here's a real beginners question and I don't expect an exact answer just
a reasonable guess or estimate.
I'm looking at a 27 bayliner, 1983, Volvo penta 260 hp
Supposed to cruise about 20.
What should a reasonable expectation for fuel usage be ?
By the hour or by the mile. info sets hull speed @ about 27, so 20 should be
a little fast as far a rpms go, If I drop back to 17-18 mph that should
increase mileage. Just guessing, I haven't ever owned a bout of this size,
but I am looking forward to some cruising
Thanks for any suggestions and help

Kickstart



I don't have the answer to your question, but I can tell you that the
only way you are going to find out is to experiment, and to do so easily
and with precision, you need to buy an inexpensive fuel flow meter and a
GPS. NAVMAN and Standard Horizon sell the fuel flow meter for around
$140 these days, and GPS prices are all over the neighborhood.

Conventional wisdom states that on a planing boat, you can divide the
horsepower of the engine by 10 to determine fuel burn at wide open
throttle. Thus, at WOT, your engine would burn about 26 gallons an hour.

I have a 225 hp Yamaha four-cycle outboard. On the rare occasions I have
run the engine at full throttle, and I do achieve full throttle (6000
rpm), the fuel flow meter just about hits 20 gallons an hour. Ouch! That
translates to 39-40 mph on my boat, which is a Parker 2520XL.

I've found the best cruise speed between 25 and 30 mph, depending on
conditions. At those speeds the engine runs between 4100 and 4500 rpm,
and the full burn is between about 9.5 and 10.3 gallons per hour. In
other words, I burn about half the gasoline at cruise speed that I do at
wide-open throttle.

Incidentally, I suggest your use of the term "hull speed" is incorrect,
but no matter.









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I have a similar boat, a 26' flybridge cruiser, weighs 7500# with a 260
hp Mercruiser 5.7. I have the stuff Harry refers to, a Standard Horizon
fuel flow meter and a GPS. I recently returned from a trip up and down
the Inside Passage to Alaska, so fuel consumption was a big deal.

I get 1.3 nautical miles/gallon on plane, cruising at 20 knots. I get 2
nautical miles/gallon at my "hull speed" which I figure is about 6
knots. This is actually the speed I almost always travel at, as like to
go slow, it saves fuel and the motor sounds the happiest.

Although if I had gone this speed on that trip I doubt if I would have
made it to Prince Rupert by now.