Order a boating magazine that tests boats such as Boating. Study the fuel usage at different speeds. You will see a pattern that is true of almost any boat.
Those who slow down to save fuel many times kid themselves and actually burn more.
A couple of examples.
A 23' Sea Ray with a 5.0 Merc.
At 1000 rpms speed is 5.6 mph economy is 3.7 mpg.
At 1500 rpms speed is 7.4 mpg economy is 2.8 mpg.
at 2000 rpms speed is 8.1 mpg economy is 1.8 mpg.
Look what .7 additional speed did to the economy.
And at 3000 mph the boat got 3.7 mpg.
Now lets look at a bigger boat.
A 40' Cabo with twin 600 hp 8.3 Cummins.
900 rpms, 7.94 mph, 2.65 mpg.
1200 mpms 9.4 mph, .94 mpg. Just 1.1 mph more but look at what it did to the mileage.
at 2700 rpms 36.6 mph .71 mpg.
If you want to slow down to save fuel you have to really slow down. Diesel will show the biggest difference.
I see many boats slowing down, maybe 10 mph, plowing water, and burning more fuel than if it was on plane.
Doug
Those who slow down to save fuel many times kid themselves and actually burn more.
A couple of examples.
A 23' Sea Ray with a 5.0 Merc.
At 1000 rpms speed is 5.6 mph economy is 3.7 mpg.
At 1500 rpms speed is 7.4 mpg economy is 2.8 mpg.
at 2000 rpms speed is 8.1 mpg economy is 1.8 mpg.
Look what .7 additional speed did to the economy.
And at 3000 mph the boat got 3.7 mpg.
Now lets look at a bigger boat.
A 40' Cabo with twin 600 hp 8.3 Cummins.
900 rpms, 7.94 mph, 2.65 mpg.
1200 mpms 9.4 mph, .94 mpg. Just 1.1 mph more but look at what it did to the mileage.
at 2700 rpms 36.6 mph .71 mpg.
If you want to slow down to save fuel you have to really slow down. Diesel will show the biggest difference.
I see many boats slowing down, maybe 10 mph, plowing water, and burning more fuel than if it was on plane.
Doug
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