lannes1769
Recruit
- Joined
- Jul 29, 2011
- Messages
- 1
i have an older 1989 sunbird coastal CC hull 17'4". Powering it is a 2006 Etec 90 w 20 inch shaft. Have SS prop of 15 p, which i think was the original prop on johnson 90 that came with the boat when i purchased it 5 years ago.
motor is on the second highest hole and cavitation plate is even with bottom of pad or slightly, 1/2 in above.
Wot is 5000 rpm. Speed is 33 - 34 mph under full load, trolling motor, 33 gals gas, two men gear etc. gps speed is within 1/4 to 1/5 mph of speedometer speed. propslip was 8% with this setup. Fuel economy runs with two people between 3.75 and 4.2 mpg . i have this prop/boat power vs economy dialed in pretty close to max economy.
What i was thinking of adding was a manual jack plate - cmc 5.5 in setback?
i'd like to add a bit more speed without going to a 19 p prop and lowering WOT down to 4600 or so. i need to take prop to prop shop to be recupped and thinking of having pitch changed to 16 or 17. but i really don't want to lose the economy i have gained. i doubled my economy over the old motor with this setup.
how would the jack plate help? and how much would the prop pitch change help in speed at wide open throttle? and how much would i gain and or lose in fuel economy by these changes.?
motor is on the second highest hole and cavitation plate is even with bottom of pad or slightly, 1/2 in above.
Wot is 5000 rpm. Speed is 33 - 34 mph under full load, trolling motor, 33 gals gas, two men gear etc. gps speed is within 1/4 to 1/5 mph of speedometer speed. propslip was 8% with this setup. Fuel economy runs with two people between 3.75 and 4.2 mpg . i have this prop/boat power vs economy dialed in pretty close to max economy.
What i was thinking of adding was a manual jack plate - cmc 5.5 in setback?
i'd like to add a bit more speed without going to a 19 p prop and lowering WOT down to 4600 or so. i need to take prop to prop shop to be recupped and thinking of having pitch changed to 16 or 17. but i really don't want to lose the economy i have gained. i doubled my economy over the old motor with this setup.
how would the jack plate help? and how much would the prop pitch change help in speed at wide open throttle? and how much would i gain and or lose in fuel economy by these changes.?
