Volvo Penta GPH Calculations (TAMD75EDC)

[Bill Lee]

I'm trying to figure out some performance figures and fuel consumption for my 2004 42' twin diesel Silverton Convertible. I tend to cruise at about 22-24 knots (around 2,200 rpm). The boat weighs about 34,000 pounds all in. I can't get any info from the Volvo people and I don't know if its boat specific. Each engine is a turbo with 480 hp. Unfortunately, I don't have any fuel flow info hooked up (I'm looking into that - subject to cost) but I want to figure out what my most efficient speed/rpm is for both sipping fuel and for keeping my engines happy. I notice that at about 24 knots - the boat tends to almost completely flatten out as opposed to having the bow ride high.... Is there any formula for calculating this type of info? Thanks,
Bill

[Chief Engineer]

Short of having fuel flow meters installed, about the only thing you can do is sound the tanks before and after a longish timed run.

[jdoe71]

go here:
Cruisers Yachts*460 Express (480-hp Volvo Penta) OEM Test Result,Overview, Best reports and accurate| BoatTEST.com

That's a test of a Cruisers 460 Express with 480 hp Volvo diesels, smaller boat than yours but close. They post the fuel consumption on the Test Results tab.

I am glad I am not feeding those suckers, 32 GPH at 2200 RPM. That's more than half our annual fuel consumption licked up in one hour!

[Chief Engineer]

Yeah....that Might take you from the Inner Harbor of Baltimore to Thomas Point Light

[Bill Lee]

Not exactly my engines - but I suppose close enough. And might I say yikes!!!! My boat has less LWL and less dry weight (and a different hull shape) but I suppose the numbers are too similar for my liking. I know what I spend on fuel per season - so I guess my trawler aspirations will bear fruit. Cheers,
Bill