Even though we boat twelve months a year, fuel burn is our least expense. We spend far more on slip fees than we do on fuel burn.
Everybody figures it differently ...
So I pay almost no attention to fuel burn numbers on the internet or via " dock talk.
TDunn,
What is the displacement of that Volvo? My Mitsu is 37hp from 107 cu. in. ... 78mm X 92mm.
The more car, truck and boat fuel I burn the happier I am. It means we're going somewhere and doing something. On our boat fuel burn is only relevant for range considerations and the ability to wait for low priced fuel to appear over the horizon.
All BS aside, our engines are quite happy at 1650 to 1800 RPM where fuel burn is about 4 - 5 gph combined. If I wanted bragging rights for low fuel use I'd own a 30' sailboat and motor along at 5.5 knots,
...........I've been told and read that the most efficient speed is the boat's "hull speed". That number is entirely dependent on the length of the waterline on the hull. Here's the formula:
Hull Speed = 1.34 * [square root of LWL].
k9medic - Is that a gas or diesel powered boat?
I have never seen a boat that length that can get near the efficiency at 9 knots.
From the Cat manual? How does that relate to the load on your boat?
Being propped 50 rpm different can make a very significant difference. Too many varibles.
Not apples/apples.