Help with fuel consumption

buggyjdav · May 2015

Good Morning. We take delivery of our 342 next weekend and are taking it 150 miles or so to our marina via the Atlantic ocean. We have a 245 gallon tank I believe and have the twin Merc 5.7's. I am wondering how much fuel we will burn on this voyage running at maybe 60 or 70% power? I thought I read the boat does about 1.3 miles per gallon, this would be 195 gallons I believe, does this sound correct? Thank you

Black_Diamond · May 2015

My 2003 342 burns about 32gph at cruise. 350MAG MPI Bravo III 22P props.

You should have 235 gal total between both tanks. You should try to have a 30% buffer to allow for running conditions, etc. running out of gas is something to avoid.

212rowboat · May 2015

New 342 or previously owned?

You're not gonna want to run a constant engine speed on that thing if it's new. You'll wanna constantly fluctuate and never hit WOT. you can do this and stay on plane, and we're only talking about a 400rpm range or so.

When you run a constant speed and load on a new engine, the rings won't float like you'll want, and instead lock in one position (like they ultimately will anyway) which will cause you compression issues later down the road... Push rods and guides will sluff and groove specific to that range, and possibly slice a third-party causing oil leak downs into the cylinder and creating a host of later issues.

If it's already broken in, let er rip, man.

raybo3 · May 2015

I am thinking my 342 burns 34 gph at about 3700/3800 rpm. That is about the "sweet" spot on my boat. Good luck with the trip and keep us posted.

Handymans342 · May 2015

raybo3 · May 2015

Really Handy do we have to get into this again........LOL

DanD2 · May 2015

rowboat, I doubt it's brand new......they haven't made the 342 since 2007 I think.

buggy.....good luck with the new boat, you'll love the 342, it's a great boat.

Stodge · May 2015

I have been playing with the vessel view I had installed over the winter. It claims that at 3600 RPM I'm burning about 25 GPH and we were going about 28 MPH. So slightly better than 1 MPG. I'm actually pretty happy with those numbers, assuming the vessel view isn't lying to me.

Dream_Inn · May 2015

Stodge, you are probably correct with that. Most 342 owners I know average around 1MPG going around 30-32mph. I know my VV is very accurate (unfortunately).