Prop Pitch?

[imported_Briano]

Hi Everyone,

I have a 1987 50hp Force attached to a 14 foot Bayliner Bass boat. I just had my friend, a boat Mechanic, put in a new head gasket among other things.
The motor runs great now, but it seems that the boat should have a bit more get up and go. We have adjusted the motor angle to where it planes out the best we could get it. It is still a bit slow to plane out though, and in rought water, it was tough to get it to plane
I dont have a Tach, and my friend said that it sounds like the motor is running about 4000 RPM.... A bit lower then it should be. The current prop on it is a 13 1/2 pitch prop, and he suggested going with a 11 1/2 to bring the RPM's to where they should be.
Now, my first question is, does anyone else out there have experience with this setup? A 14 foot bayliner and a 50 HP Force motor? I am just curious what size prop you found to be best.
Secondly, can anyone else think of anything that would cause this? Compression is good, it runs about 144 degrees on each cylinder, and it idles nice and smooth, so everything with the motor appears good. He said a lower pitch should be the next step to get everything in order.
Any opinions or ideas?

Thanks!

 

[roscoe]

Re: Prop Pitch?

Lower pitch prop sounds good.
And a tach, even a tinytach.com would be nice.

Don't expect miracles out of that boat/motor.
They never were fast or powerful.

 

[imported_Briano]

Re: Prop Pitch?

Thanks Roscoe. It just so happens Tinytach is located near my house, so I will stop and pick one up today.
I realize that this boat and motor combo isn't a Stratos. The thing was, we messed with the motor angle to as low as it would go. Also, my friend noticed the carb was not quite all the way open at WOT, so he adjusted the linkage, and that helped alot.
We got it to the point where when it did plane out, that boat was really moving. It was just that getting it there was tough.
The prop that is on the boat, we could not find any markings to indicate what it was. The other prop I have is the 13 1/2. I know it is hard by looking by eye, but we compared the 2 and they look similer, so we are assuming that they are both 13 1/2.
The one on the boat has seen better days.... Lots of nicks, the edges warn down, stuff like that. Maybe I will put the new 13 1/3 on first to see how that does before I order the 11 1/2.

 

[steelespike]

Re: Prop Pitch?

You won't really know where you are at until you get the tach and see how it does with the good 13 1/2 prop.
If you are trimming all the way in to get out of the hole
better you may be hurting your top speed because the boat is running too flat.You may want to move some weight forward.So you can run trimmed out more and still get some hole shot.The battery and or gas tank come to mind.Your motor developes its power at 5,000 rpm so you need to at least be there at wot.After you have trimmed everything to the best performance you may want to consider smart tabs to help your performance.
Do a little search here for info on the excellent results with smart tabs.