How do i figure out what prop i need 198085not sureknow its in between them though 90 hp mariner

" well my prop was damaged , i

" well my prop was damaged , i went to buy a new one and didnt have enough info so , i need to find out how to obtain it .....

first of all , ive been looking at props , and ive come to conclusion that i need a 13" diameter 19 pitch prop(i think)the old prop is so bad i cant get numbers off of it , so thats out .

i keep reading about different sized gear cases and things of the sort . what does this mean ? how do i exactly determain what kind of prop i need ? someone help me here , i am lost when it comes to props "

" what kind of engine on what

" what kind of engine on what kind of boat? need all the info i can get before i give you an opinion. ie: rpm at wot, engine height, hp of engine etc... give all you can "

" its a 1980???? 90 hp mariner

" its a 1980???? 90 hp mariner inline 6 . the numbers i got from the previous owner on the motor are s721-335 (the "s" may be a 5 as well , i cant really understand his writing)

the boat is a 19 ft winner closed bow , very light boat , with a pretty wide beam

with a 19 pitch prop , it ran about wot at about 5k , about 40-42 mph(on gps) the main thing im concered about is the difference between 1/4 and 3/4 gearcases , i dont know what this means .

i know its a 13 in diameter prop .

as for engine height , no clue
im assuming its a standard mercury longshaft .

like i said , the old prop is so damaged i cant even get the numbers off of it .

thanks in advance "

myself i would drop 2" in

myself i would drop 2" in pitch so icould get the rpm up to around 5500 where is where it should be running at normally.

" Anyone familiar with 1990 Fo

" Anyone familiar with 1990 Force 15 hp outboards? I cannot find a manual and have a problem with the kill switch. No matter which way I wire it, I can't get the kill switch to work. It's got dual coils with separate wires for each... Any suggestions? "