prop suggestion

[Nitro_boy]

I have a 2001 16 ft alumacraft fishing boat that has a livewell and an interior with a tiller steer 25 hp johnson motor which is a 2000 model. The motor runs great but won't plane out with this boat. They weren't a matched set so I'm curious as to what prop I should put on it. The boat is pretty heavy with 2 or three people. THanks guys.

 

[Irv964]

Re: prop suggestion

I have a 2001 16 ft alumacraft fishing boat that has a livewell and an interior with a tiller steer 25 hp johnson motor which is a 2000 model. The motor runs great but won't plane out with this boat. They weren't a matched set so I'm curious as to what prop I should put on it. The boat is pretty heavy with 2 or three people. THanks guys.

You really need to read this first and then post again with the required info. This link is right at the top of this forum, maybe it should be in bold red letters??
http://forums.iboats.com/showthread.php?t=287818

 

[cr2k]

Re: prop suggestion

the fact that the boat doesn't plane may have nothing to do with the prop if the engine is not enough for the boat or not mounted at the right height.

Your engine should run at max RPM at WOT no more very little less.
You boat should be loaded as will when using for this test.
If under RPM lower pitch and or diameter.
If over RPM higher pitch.

If you run too high a pitch prop on a 2 stroke engine it will build carbon in the combustion chamber and eventually the head and the piston will touch, not even enough for you to notice, but very shortly after your rod bearings (tiny rollers) will make there way around your engine. Really, I've even found them in the carbs. go figure.

If you run too low pitch your rod bearings will whip too much from over rev and, well, same out come as above.

Basically you DO NOT prop for boat speed you prop for engine RPMs. then try trim etc. to got on plane.