Boat will not plane at higher alitudes.

[paintitpaul]

I have a 25 foot crownline that runs & planes fine at 2000 ft, when I take it to Lake Powell approx. 3700 ft, boat will not plane or run over 3000 rpm. My prop is the smallest pitch 22/ counter rotating, Mercruiser outdrive, Bravo Three, 7.4 L, Chevy 454. I really need some advice.

 

[anesthes]

Re: Boat will not plane at higher alitudes.

Your making far less power at 3700ft than at 2000ft. And if you were at sea level, your boat would amaze you i'm sure. <br /><br />Try cutting some fuel when your at 3700ft to compensate for the less o2 your motor is getting.<br /><br /><br />-- Joe

 

[outboardguy]

Re: Boat will not plane at higher alitudes.

Paul, I work on a lake that is at 5500 ft level.All we do to our boats is to drop the pitch of the prop or props to compensate for the change in altitude.Anything above our altitude and it is recommended to change jets in the carb.As you say you are already at the lowest prop available, so that is not an option.So if your boat has a carb you can change the main jets to a smaller size to help gain some ponies back, But you must be cautious, because if you change jets and don't remember to change back when you go back to sea level you will burn up your engine.I have a feeling that your engine is probably in need of a good tune-up or you may have an exhaust restriction.In any case you shouldn't be having that much trouble at 3700 ft.

 

[achris]

Re: Boat will not plane at higher alitudes.

The other option suggested by the manufacturer is to get higher ratio gears in the leg.<br /><br />Chris...........

 

[edfresh]

Re: Boat will not plane at higher alitudes.

Paul,<br /><br />My old Datsun 240z would run perfectly when at lower altitudes but I had to readjust the carb air/fuel mixture at higher altitudes. May be too lean at that altitude. Try adjusting the carb at idle up there before going into the water.<br /><br />Ed Freshwater

 

[alumistar]

Re: Boat will not plane at higher alitudes.

paul, change the jets but only after you find everything else to be clean and free of debris.

 

[anesthes]

Re: Boat will not plane at higher alitudes.

Originally posted by edfresh:<br /> Paul,<br /><br />My old Datsun 240z would run perfectly when at lower altitudes but I had to readjust the carb air/fuel mixture at higher altitudes. May be too lean at that altitude. Try adjusting the carb at idle up there before going into the water.<br /><br />Ed Freshwater

Too rich.