Confused on prop selection

[U Rest U Rust]

I just bought a 1989 23' Sea Sprite. it is a full cuddy with head, fridge and sleeps 4, pleasure boat. It seems heavy. Sterndrive mercruiser 5.0 with alpha 1, 1.5 gear ratio. The problem is that the prop that was on it has huge blades and the 2 other props on the boat are 14 17 pitch. when I asked the previous owner which prop he was using he doesnt remember. it takes a long time to plane out and when it finally does. the max speed was 32 (gps) and the rpm's 4100. Mercruiser online says 4500 rpm and 48 top speed??? I have not tried the bigger prop because it comes real close to the zinc tab. What size prop would work well for cruising and what is the rpm specs for WOT?? I looked up the merc site and they are recomending 14.2 18. The carb, fuel filter, rotor and cap was just replaced and it does run fine. New to this stuff. where should the power tilt for engine be and trim tabs when trying to get planed off?




Thanks a ton

 

[Silvertip]

Re: Confused on prop selection

Trim tabs at about 15 degrees down. Outdrive trim down. As you come up on plane bring the tabs up. Then play with outdrive trim. WOT rpm = 4800 rpm. Whatever prop gets the engine at that rpm with wide open throttle, tabs up, trim out, maximum speed is the right prop. Maximum speed is what you get under those conditions.

 

[U Rest U Rust]

Re: Confused on prop selection

Thanks, will give it a try. appreciate the fast reply..

 

[U Rest U Rust]

Re: Confused on prop selection

I set the tabs at 17 and the alum 14 17 pitch still had very bad hole shot. still would not plane quick. changed prop to another one on the boat 16 20 alum pitch. planes real fast now and handles better. this issue now is rpm's are only at 3800 wot and 35 gps speed. there is a 14 17 ss on board as well. should i try that or pick up a 16 17 alum to increase rpm??? this is not as easy as people think!!!!

 

[U Rest U Rust]

Re: Confused on prop selection

I set the tabs at 17 and the alum 14 17 pitch still had very bad hole shot. still would not plane quick. changed prop to another one on the boat 16 20 alum pitch. tabs at 10 now and planes real fast and handles better. this issue now is rpm's are only at 3800 wot and 35 gps speed. there is a 14 17 ss on board as well. should i try that or pick up a 16 17 alum to increase rpm??? this is not as easy as people think!!!!