slow to plane & max rpm.

[capnraysr]

Bought an 84 Skeeter Starfire w/ a 150 Black Max. Had 2 cyls w/ low to no compression. Found an 81? 150 hp & swapped 'em out. Now she run's like a champ but it takes a long time to get on plane. I have to trim the motor all the way down so that it almost touches the transom. Would like to know what the max rpm range & what the best prop set up is. 3,4 or 5 blades? This is my first small boat. I run towboats for a living.

 

[Maxz695]

Re: slow to plane & max rpm.

A smaller diameter prop increases RPM. Say going for a 12 to an 11 or 10. A bigger pitch can give you more MPH say from a 10 to a 12 Pitch what size prop are you using at present may help someone dial you in a bt better than the discription you put fourth. Taking a long time to get on plane would indicate your pitch is to much, or the diameter of your prop is too large

 

[capnraysr]

Re: slow to plane & max rpm.

A smaller diameter prop increases RPM. Say going for a 12 to an 11 or 10. A bigger pitch can give you more MPH say from a 10 to a 12 Pitch what size prop are you using at present may help someone dial you in a bt better than the discription you put fourth. Taking a long time to get on plane would indicate your pitch is to much, or the diameter of your prop is too large

Sorry for lack of info. the prop that is on the boat now is a tempest 3 blade 48-825866 A45 25p. I also have a 4 blade M13 3/4x 22. Do you know the max rpm range for this 81, found on the correct age, 150 hp motor.

 

[Faztbullet]

Re: slow to plane & max rpm.

The rpm for that 1981 engine is 5000-5500rpm and it will never turn that 25p!!! The 4 blade 22 will be the closes but the best prop is a 20p turbo.

 

[Alumarine]

Re: slow to plane & max rpm.

It's normal to have the motor trimmed down to get on plane.

 

[capnraysr]

Re: slow to plane & max rpm.

Thank's guy's, I will go swap props now. I only get about 4500 rpms with the 3 blade. Maybe after the swap it will come all the up to 5500 or so. She's doing about 45 or so with the 3. might hit 60 with the 4.

 

[Maxz695]

Re: slow to plane & max rpm.

Again going down in pitch will lessen MPH and increase RPMs hope it all works out

 

[Faztbullet]

Re: slow to plane & max rpm.

Again going down in pitch will lessen MPH and increase RPM

Not always... If you use the 22 pitch and can turn 5500rpm WOT you will pick up 5-7 mph..