Re: New (used) Carver gas consumption question
Referring to my post to the topic started by walleyehed:
New to forum, not new to boating.
1985 Riviera currently.
This is a bit longer than I like but should provide you with some meaningful information, if you're not already familiar with it.
Generally, if you're going for best economy (MPG), running at hull speed is best.
Hull speed (Knots):
Sq. root of waterline length (LWL) multiplied by 1.3.
Example, a 28' LOA boat having a waterline length of 25' is sq. root of 25 (5) multiplied by 1.3 = 6.5 Knots.
Knots to MPH = Knots X 1.15, in this case, 6.5 X 1.15 = 7.48 MPH.
OR:
Sq. root of LWL X 1.495 = 7.48 MPH
Other than that, running in the "Sweet-spot" (usually 3,000 to 3,400 RPM) will provide the best compromise between consumption and time.
Although you didn't mention the length or weight of your Carver, more to your point:
My 1988 34' Sea Ray Sedan with twin 454 350HP Mercruisers ran 22 Knots (25.3 MPH) at 3200 RPM burning 20 GPH, which equates to 1.1 NM/gallon (approx. 1.27 MPG).
Considering the Sea Ray has prop-pockets, which, when going ahead (it handled terribly when going astern), lends to better efficiency than a boat without them, your Carver with twin 454s will be something less that that (I'd guess 80%).
Therefore, extrapolating from known data and applying it against the unknown but assumed, I suspect your Carver could get around .9 to 1 MPG, which is really not too bad.
Hope this helps.
If you want, contact me privately.
