i think i spun my prop... help

[eggsuckindog]

True but it still needs RPM, the other factors are more bow lift vs stern lift and stuff like that. I thought you were getting the 17 fixed??, the motor lugs like having your car in too high a gear and that hurts performance and shortens engine life.

[Blue197320]

i went today and bought a brand new 15 x 17 like my original. i think the new prop alone helped. cruise is still the same at 28 mph @ 4K. and top end is now 38 mph @ 55K. so i guess ill be sticking to my original prop.
egg, so even cruising at 4K with that 14.5 x 19 putting a strain on the engine? out of the hole performance cant be matched tho.
-evan

[SECF3114M73J]

Ideallly you want your motor to rev in the high end of it's range. The prop that only turned 4800 is like driving on the highway in second gear. You'll shorten the motors life and burn more gas at a given speed.

[Blue197320]

the 15 x 17 seems to be the best prop. 5500rpm gives 38.1 mph with 3 people in the boat. and out of the hole performnance is good if motor is trimmed properly. guess i have to put my hydrfoil back on the cavitation plate..
-evan

[eggsuckindog]

Sounds perfect, 28@ 4K isn't bad at all, my 20 w/200 is around there at 3500/3600- you mentioned the cav plate, have you checked the engine height? the cav plate should be approx 1" above the bottom of the hull. This can make a boat ride and handle much better if its correct.

[Blue197320]

well i think why it was cavitating the other day was because i had the engine trimmed too high.. when i tested that new prop the day before it jumped right onto plane. so this weekend i will try it again with the motor trimmed down.. i have one of those fins that mounts on the plate that i used to have on there. what do u get on ur 20 at WOT with the 200? and what 200 is it?
-evan
-evan

[eggsuckindog]

Its a 94 Merc XRi and best I've seen was 49 with just me, I just bought it and a better prop is not at the top, but it does have a T Top too. Yes when getting out quick have the motor trimmmed as far in as possible then bring it up some, unless you have alot of cup you can't trim too high before losing bite.