Re: 1986 90hp merc. prop size?????
It depends on the size, weight, friction, (that is based on the hull cornfiguration of yer boat).
If it is fairly light weight semi v you could start with a three blade aluminum 19p (which most of those engines came with).
If it is fairly heavy or has a high friction hull you could try a 17 p three blade aluminum.
If it is very light weight very fast, (low friction type hull, [maybe a tunnel or some such]) you could try a 21 p three blade aluminum.
Take yer pick, hope this helps ya. JR
