Re: 6hp outboard for a 25' boat?
A high torque 6hp long shaft would work, or a long shaft 8 or 9.9 for that same boat would work.
This from me, who has NO chop, no winds (usually) and I have a 25 footer #3500 displacement, and use a 3.5hp upgraded from 2.2hp. Yep... Oh and with 2-3 foot chop and 30mph winds, I still was able to get to 5knots.
Find a nice 6 with a decent pitch prop is my bet.
"Rum Line" an S2 7.9 - cheap, fast, trailerable, and paid for.