what propeller???

[whitly]

ok, so i'm putting an optimax 175 on a 20' seafari. how do i choose a propeller? aluminum vs stainless. what pitch? and what does that mean to a newbie like me? the yard is happy to sell me whatever i want. my outboard guy says go aluminum, at least until i'm sure i have the right pitch. they both say if i whack it on something, stainless will be a bigger problem, both to straighten and for the shaft. so many decisions.