Whats the correct pitch for my boat?

Just last week I lost my prop and am looking for the correct prop to replace it. I'm not looking to do anything crazy with the boat. I have the correct diameter but am lost on where to start for the pitch. Any suggestions would be greatly appreciated. Here is my info. Thanks in advance.

1) Performance issue you are trying to correct.
Just looking to do some fishing. Nothing series

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Unknown lost at the bottom of Oneida Lake. I would assume aluminum.

3) Current prop diameter and pitch (required).
Diameter.......10 3/8
Pitch............This is where I need help. Should I go with a 10, 11 1/2, 12 1/2, or 13??

4) Wide open throttle RPM and speed with an average load (very helpful)
I have no idea about the RPM. My average load is about 400 pounds (2-3 people)

5) Engine/drive make, model, year, and HP
1990 50hp Force

6) Boat make model, year, length and weight
1990 15' Maxum runabout. My guess on the weight is 850 pounds.

Re: Whats the correct pitch for my boat?

Not much to go on, but I will give an opinion based on some wayback experience. 15.5 foot trihull, Chrysler 55hp, a 12p would be hard to get onto plane with more than 2 people, hard to pull skiers. An 11 was about right, it hit the same top speed as the 12 unless it was just me in the boat (with the 12). A 10p overrevved. So with those choices I would get the 11.5p.

Do you know the speed you were hitting before? The combo I just described would get to 29mph, that seemed to be the limit for the 55hp I had.

Re: Whats the correct pitch for my boat?

Maclin said:

Not much to go on, but I will give an opinion based on some wayback experience. 15.5 foot trihull, Chrysler 55hp, a 12p would be hard to get onto plane with more than 2 people, hard to pull skiers. An 11 was about right, it hit the same top speed as the 12 unless it was just me in the boat (with the 12). A 10p overrevved. So with those choices I would get the 11.5p.

Do you know the speed you were hitting before? The combo I just described would get to 29mph, that seemed to be the limit for the 55hp I had.

Click to expand...

Interesting comment. Back in 1971 I bought a 16' Chrysler Sport Fury tri-hull. I had a wife and 4 smaller chillins and I don't remember the prop pitch, but it is what came on the engine. We liked to go out on a lake on Sunday and picnic and water ski. Performance sucked.....I mean really sucked. I took the rig back to the selling dealer and traded the 55 for an 85 and things improved significantly, but still sucked. Next year bought a Caravelle deep V tri-hull and a Johnson 125......now we are rolling and not only fast, but smooth riding where the Chrysler beat you to death.

My experience.
Mark