Prop/Power/Pitch

[1maniac]

Hey folks, I have a 14.6 foot Bayliner Capri Bowrider. It comes with a 50 HP merc, 10 pitch by 11 1/2 diameter prop, and a hydrofoil stabilizer. I boat at about 6200 feet on a deep water lake. I have no tachometer.
My question is this. When carrying two 120-150 pound adults, and 6 gallons of gas, the fastest I can get is about 22 MPH. Is this about average or should I be going faster? The boat also takes quite a while to get to plane. I recently refloored and foamed the inside. There was plenty of water on board. The weight problem is NOT an issue. HELP......

 

[steelespike]

Re: Prop/Power/Pitch

Technically at 6200 ft the motor needs to be re jetted (smaller jets)we really need to know your rpm. Without rpm there is no way to know what pitch to suggest and you won't know if the motor is reaching its designed rpm.Lugging the motor (low rpm) can be as bad as over reving in the long run.
A Tiny Tach is about $47 and easy to install.Without it you can't even tell if your setup is right.

 

[1maniac]

Re: Prop/Power/Pitch

Thanks for the information, I'll try the tach thing. Do you know if this is something that Bass Pro Shops will carry? There's one in Denver. I have had several people tell me to have the carb rejetted for altitude ( I am an enemployeed auto mechanic), I would think to rejet a boat motor would act the same way as a car engine would, they starve for oxygen just the same.
Boating is new to me and I just do not want to go out and spend unnecessary money on things that do not work. Once again, thanks for the info.........

 

[1kruzer1]

Re: Prop/Power/Pitch

You can't make up for lost horsepower by re-jetting, but you can maximize what you have to work with. If your two-stroke outboard is jetted for sea level to 3000 ft and you are running that jetting at 6000 feet, you are running way rich and the motor is not developing it's potential power for the altitude. Stop by any Merc dealer with model and serial number and they'll have a chart showing the correct jets to install in your carbs, or you can look it up on-line. It'll make a performance difference. After the jetting change you must have the tachometer to be able to know if you need to make a prop change or not. You can rent or borrow a portable one if you don't want to permanently install one on the boat. Good luck!

 

[steelespike]

Re: Prop/Power/Pitch

What year Merc?
A properly jetted motor will lose about 3% for each 1000 ft of elevation.
Jetting works but only to allow the motor to develope its max 6000 ft power.
With a schematic of the carb I would think you could do the jets your self.