"Hello Doug:
Normally when
"Hello Doug:
Normally when you go down in Pitch you will gain more RPM's and lose top end speed and MPG. BUT you will gain a good amout of holeshot and you will plane off much faster. Now with that said the diameter size plays a part in this. For example, when I first got my 14.5" x 17P ss prop I could only turn 4300 RPM's. After I had 1/2" taken off (took it down to 14.0" x 17P I gained 200 RPM's). This put me at 4500 RPM's.
Now did I understand right that you were turning 5000 RPM's with that 18 pitch plastic prop? If so a 17P should in practice turn even faster, (depending on the diameter.) Just do not push that little engine over 4800 RPM's. Now if you were turning 5000 RPM's with the 18P prop you may have wanted to try a 19P or 21P ss Prop. That should keep your RPMS around 4800 for a 19P or 4600 for a 21P depending on the Pitch.
Do you carry a lot of weight in the boat, ie.. haul several people each time out?
Please let me know about this RPM thing ie... were you really spinning 5000 RPM's wit the 18P plastic prop? If so you need to get a larger pitch that 18P.
Take care,
T."