Fuel burn

A quick question for you GB 36 owners out there: we've seen a few discrepancies for gph on the 36 equipped with twin 120 hp Lehman's. What is a true fuel burn range?

0 to 6 gph for a 120 Lehman.

Ted

So that's quite a bit of difference. Normal cruising (6-8 kts), straightforward conditions, are we closer to 1 gph or the 6 gph? Broker (who previously owned the boat and seems to be a straight shooter) said less than 3; others I've seen say 5+. I know there are a lot of variables, but just trying to gather as much info as possible.

Huge difference between 6 and 8 knots.
Single or twin? Most are twins so 3 to 5gph.
That’s my guess.

Thanks -- posted that it was the twin Lehmans. Appreciate some real world anecdotal evidence.

O C Diver said:

0 to 6 gph for a 120 Lehman.

Ted

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melissar said:

So that's quite a bit of difference. Normal cruising (6-8 kts), straightforward conditions, are we closer to 1 gph or the 6 gph? Broker (who previously owned the boat and seems to be a straight shooter) said less than 3; others I've seen say 5+. I know there are a lot of variables, but just trying to gather as much info as possible.

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That was supposed to be my attempt at humor. Roughly every 20 horsepower requires 1 gallon. So, a 120 HP engine should burn 6 GPH at full power and nothing when it's off.

Ted

Ted...I must be really tired today. Accept my belated laughter!

A knot below hull speed could reduce fuel consumption rate by at least half.

I'd figure a GB36 with twin 120's would burn 3-4gph total at 7kts.

Ski in NC said:

I'd figure a GB36 with twin 120's would burn 3-4gph total at 7kts.

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Agree.

Ski in NC said:

I'd figure a GB36 with twin 120's would burn 3-4gph total at 7kts.

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Agree

Fuel burn is totally dependent on how fast you go. For my boat a 5 knot cruise speed will burn 0.2 gph, 6 knots is about 0.4, 7 knots 0.75, 8.5 knots 1.8 gph and 9.2 knots (wide open throttle) 2.3 gph. So pick your speed to get the fuel burn you want. My boat is 32'8" with a 32' LWL and a 9,500 lb displacement. LWL, displacement, hull form and speed determine your fuel burn.