Buddy has a 17’ older whaler that has eaten 2 engines… Since the only engine in his budget was a 1991 150 Force… thats what we put on there.
Oddly enough the motor runs incredible, but no idea where to even start with prop pitch. motor came off a bigger Trophy, and had 15p beat to hell prop. We put in water just to see how it sat, and looked good eben with 300lb guy in back.
Maybe try a 19?
Yes we reinforced transom, i know insurance issue… not my boat, don’t care… just trying to help him get a prop.
I ran some simple calculations using the following as a basis. 1500 pounds, 90 hp, 17 pitch prop, and 40 mph with a 10% slip to get a hull factor. Plugged in 150 and got an estimated speed of 51.5 mph. You can use this to work backwards to a prop pitch using speed, slip, and gear ratio with an online prop pitch calculator. If you have good performance data from the previous engine I can run a more accurate calculation.
Need:
Wide open boat speed and engine rpm
Gear ratio
prop pitch
I have a 17’ with a 200 black max, and have run from a 4 blade 17 to a 26 chopper all have worked for different applications don’t take much to push the whaler!
Thanks! Found a couple props in my garage i was gonna try… but apparently Merc props won’t fit on that year Force.
We ordered a cheap prop on EBAY just so we have some kind of starting numbers, and a tiny tach to get RPMs.
Thanks again
