JLR:
Two thoughts for you:
-- if you are near Montego Bay, that's probably your best bet to find a normal
boat owner (not charterer) with whom you could strike a deal. You can call the YC there ahead of time and inquire...but it may take walking the docks. I would think Ochos Rios an unlikely prospect. Another option when thinking of the North Coast is to call the marina at Port Antonio...but by land that's a lengthy (in time) distance to drive given the roads.
-- the prettiest J coast IMO is the west end, which includes a number of resorts and some beautiful tropical settings. If you would like to consider sailing a daysailer, beach cat or other simple
boat, that's where I'd look first. All the resorts should know one another's capabilities so contacting one, if they can't serve you, might generate referrals to others.
Jack