best cruising rpm

[bb king]

Hi this is my first post I have a 91 maxum cuddy with an 89 125 force what would be the best cruising rpm for maximum fuel mileage,this puppy is hard on fuel but runs very well,I have ordered a 15 pitch prop to replace the 17 to get wot rpm up to 4800 range.I have been cruising in the 3200 to 3400 range.

 

[jerryjerry05]

Re: best cruising rpm

What is the max WOT/RPM with the 17p ?Have you done a compression/spark test? Jerry

 

[bb king]

Re: best cruising rpm

wot with 17p is 4300 compression and spark are good

 

[maxum247]

Re: best cruising rpm

I have the 1989 maxum version of your boat with a 1989 125 Force, 15 inch prop, as a cuddy it ran about 37 mph according to my father-n-law, still runs about 37mph at 5000 rpm since I converted it to bowrider. Seemed to cruise good at about 27 mph, fuel mileage seems to be good overall. max!

 

[bb king]

Re: best cruising rpm

What would your rpm be at 27 mph Max.

 

[GrindKore]

Re: best cruising rpm

I have 1990 FORCE 90 on a 16.5' bow-rider. Currently I have 13x19P cupped Michigan Wheel prop. At WOT I get is around 4000 RPM and about 34 MPH, best fuel economy with this configuration is between 3000 and 3200RPM which gives me about 22 to 25 MPH.

I believe I'm lugging this motor with 19P cupped prop and will likely reduce pitch to 17" or even 15". Although at the moment I'm not sure what the problem is since previous owner always had all 19P props on this boat.

For any plaining hull vessel, the best fuel economy occurs at minimal speed that the hull can maintain stable plain.

 

[maxum247]

Re: best cruising rpm

What would your rpm be at 27 mph Max.

It's been too long, I can't remember! max!