115 2-stroke What is the correct prop.?

[sean]

Little help
115 2-stroke 2001
What is the correct prop.?
20 ft Pontoon, came with 13.37"x17"
800-4000 RPM fine, after 4000 the prop will not hold.....
Second prop same size and pitch.
115HP should rev up to 5000 correct.
is 17" to high for a pontoon...
It feels like the motor is coming out of the water, but you can look back and see the fin is at water level........
any help would be great...
Sean@NC

[boats.net]

The motor may be mounted too high. We try to prop pontoon's on the high side of operating range because they tend to carry a lot extra weight onboard. A 15 pitch should give you about 400-500 more rpm,s.

[sean]

115 2-stroke

the motor is down as far as it will go, in this case will a jack plate help?
I feel the owners before had a different motor on this craft and they found this motor would fit....

[boats.net]

Most pontoons have a 20 inch transom but if it's a big boat it may have a 25 inch transom. Is there anything mounted on transom in front of motor that would cause cavitation?

[sean]

I will take photo's this weekend, hoping this will help.