Help with fuel consumption?

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.

- Bill Kiene

Kiene's Fly Shop Sacramento, CA, USA

Web site: www.kiene.com

I'll take a Wild Stab: I had an 18ft Campion with a 120hp 4-cyl Mercruiser. It was quite a bit heavier that yours, had a top end around 30mph iirc. And iirc (it was a few years ago) I got about 4-5mpg at cruise (20-25mph). I'd guess you should be getting around 5 or so.

Does this help? Lloyd Sumpter "Far Cove" Catalina 36

This is a fairly light boat, 4000 rpm might not be the most fuel efficient cruising speed. The boat will probably plane at 3000 rpm. I had a Volvo 6 cyl. a few years back, and the best mpg was at 3600 rpm.

Your buddy can buy a Floscan fuel meter for about $300, or he might be able to borrow one at his local marina mechanic. This will give his boat's best mpg and gph.

"Bill Kiene" <billkiene@kiene.com> wrote in message

1) the point at which it rises over the bow wave and is "on plane" 2) dead slow.

A wild guess is that your friend's boat might get roughly double the nmpg at 30 that it realizes at 40. If you check the fuel consumption chart for most engines, the curve gets extremely steep in the last 15-20% of the RPM range. If he's running at WOT to make that 40, he's also spending a lot of money that's invisible (for now) on additional maintenance and a premature rebuild.