Fuel Consumption?

[kdumph]

Trying to get a rough idea of what kind of fuel consumption I get on my gas 41 aft cabin. It has 454 mercruisers in it. I don't take her to wot often, and usually keep it around 1000rps to put around with.

 

[rondds]

KD
at 3200 RPM you'll burn about 30 gph. At 1000 rpm, you'll burn about 6gph. You'll have to check your speeds at these rpm but with that boat and these engines, you're best off at displacement speed. It doesn't matter what boat you have. These engines all burn the same at each a RPM, if tuned and loaded properly. The boat's weight and wind resistance govern the speed. Throw that engine in a single screw 25 footer and at 3200 RPM you'll be flying along at probably 28 MPH, thus averaging almost 2 MPG, which is great for a boat. In your boat, at 3200 you're probably chugging along at 14-15mph, getting about 0.5mpg.

 

[Henry Boyd]

Our numbers are slightly different, but track Ron's. My single 496 burns about 16-18 gph depending on drive trim. So the slightly smaller displacement volume of the 454 is going to consume less gas (15 gph vs 16-18) and air volume at the same rpm setting. I've also noted that the guys with twin 496/8.1s have the same burn profile that our single has.

Henry

 

[Summer Fun II]

If you own a boat and you're worried about the burn rate of gas .

SELL THE BOAT !!.

 

[mawyatt]

Henry is correct regarding the 8.1L. We burn about 33~36GPH at ~3400rpm with twin 8.1L.

 

[Brian Nagel]

This is our first season with our 2005 340 Sundancer and we are looking at gas consumption as well. Our anchorage is 240 miles round trip and the boat holds 200 gallons (closest gas is 120 miles). We are carrying a 12 ft Zebec tender c/w a 9.8 kicker, and are packed for 10 days. Any advise on the optimum travel speed/rpm's would be greatly appreciated.

Brian

 

[Henry Boyd]

If you own a boat and you're worried about the burn rate of gas .

SELL THE BOAT !!.

Some of us are interested in fuel burn rates not because of the cost, but because running out of gas in the ocean is generally considered a bad thing.

 

[Brian Nagel]

I agree with Ciao Bella. We are not overlly concerned about the cost of gas, but want to ensure that we have enough to get home as well.

Brian

 

[riptide]

Ron, with 7.4 x2 @ say 1350 I should burn 5 gal. a hr. per eng in a 390 ? I thought it would be better than that I am at hull speed I think Rip

 

[rondds]

I just came back from ride and when going through the no wakes at 1000 rpm, I was getting 7gph. Didn't check 1350. Saw this post too late.

 

[Angry Ranch Hand]

KD
at 3200 RPM you'll burn about 30 gph. At 1000 rpm, you'll burn about 6gph. You'll have to check your speeds at these rpm but with that boat and these engines, you're best off at displacement speed. It doesn't matter what boat you have. These engines all burn the same at each a RPM, if tuned and loaded properly. The boat's weight and wind resistance govern the speed. Throw that engine in a single screw 25 footer and at 3200 RPM you'll be flying along at probably 28 MPH, thus averaging almost 2 MPG, which is great for a boat. In your boat, at 3200 you're probably chugging along at 14-15mph, getting about 0.5mpg.

Well stated.