Moved the thread from Suggestion Box to "Sport Yachts ".
What do you have for engine's?
Typically marine engine efficiency if not measured or rated at speed. Rather it's measured at Gallons Per Hour (GPH) based on RPM's.
Tide, current, wind and sea state can all impact speed. Running with 3kt vs. against 3kt will give you a 6kt variance. It's more accurate to measure GPH based on RPM.
The problem is I've never owned this boat, before and running multiple trips to determine range is an expensive, and time consuming process.
The engines are 8.3L MPI 1999's with 20" 4 blade Nibral props on a V drive.
I'm not sure why a sport cruiser would have 4 blade props, but they do give good bite when docking.
GPH per RPM is only half the picture, the other is MPH per RPM.
I can time the voyage to eliminate head currents, except on a round trip they should cancel out.
Most boats have a sweet spot where they get the best bang per gallon. The highest mileage is just above idle where the props are spinning fast enough to bite, but who wants to cruise at 2.5 knots?
There should be another one just below hull speed that I can calculate, but variances in hull design can skew this speed from the calculated value.
And another one at planing speed where the fuel consumption will be high but there should be a spot where speed vs fuel is at a maximum.
I'm sure in a few years I will know these values if I keep track of fuel usage in a log, but some one with a fuel flow meter that has already done this will know these numbers.....and hopefully post them.
Not an exact science but I would look at test data in reviews to similar boats in power, length, and weight. These provide the sweet spot for cruising speed and GPH, then knowing you tank capacity you can calculate range.
range on a 3700 scr 1999
Linear Mode
