I put my 150 on a 186 astro that had a blown 150 my motor has a 24 4 blade turbo prop. I'm having trouble getting on plane once on plane it will run bout 50 mph. Now the other motor had a 3 blade 21 prop on and the guy I got the boat from said it would 68mph and jump out the hole. Anyhow could that be my problem thanks

Yes, no, maybe...need more details.

What motor?

What were your rpms at full throttle full trim? That number is what you determine prop size from.

And you can't go 68 with a 21 pitch prop and a stock outboard, he's BSing you.

prop calculator shows close to 7k rpm with a 21p and a 2:1 lower at 68....


the 24 sounds about right for a good all around prop for that set-up, i'd look into some other areas for the perf problem. A good place to start would be a compression check..

i'm with pat on this one.

what year is the 150 merc?

a good 23p laser II will be a good starting place, assuming you have an older mercury.

another question is. if the 4 blade bogs outa the hole. is the gear case on this 150 the small gear case?? if so, that's why it's bogging. it may need vent holes if that's the case.

It's a 150 mairner it's showin 3000rpms trimmed out the boat had a 150 force motor on it that was blown. My motor sounds the same as did on my 178 hydro sport trimmed out at 5600rpms 50mph is plenty fast I just want it to get on plane faster And I have the jack plate all the way down

It's an 83 yr modle

I wouldn't know the difference it looks like it fits the motor is there a way I can find out the size of the gear case. And where could I get vent hole put in it around Tyler

take the time to take it to steve, he will get it right for ya.

Sounds good thanks information

might be best if you are close enough to bring the boat here.

i'm open saturdays 8-12

call first to make appointment please.

if your too far away take some pictures and email to me and i'll try to help you further.
steve@stevescustomprops.com

I will send you some pics of the motor and both props when I get off the ambulance in the mornin. I live outside of jacksonville so I will call before I head up there

sounds great man. thanks.

and thanks for the job you do!!!