To get back to the OP - there are two options for bottom cleaning: pull it up on the trailer and powerwash/scrub it, or have a diver scrape the bottom. I know there are a couple divers that do boats in the marina at the Port of Friday Harbor that we used on commercial boats; check with Tami in the marina office, and she may be able to give you some names.
The water in the Salish Sea stays pretty chilly even in summer, which does slow down growth/barnacles; in our sub-tropical climate, an unpainted bottom will be an issue in 10 days or so. If you plan to leave your boat in the water in the San Juans, be sure to have whoever does the work use a bottom paint that will remain effective after being put on a trailer (assuming you want to trailer your boat around). Not all bottom paints are the same. A cruddy bottom will affect boat performance.
When we had our C-Dory done, we applied two coats of barrier paint (after roughing up the gelcoat with sandpaper, then a different color bottom paint, so it would be apparent when the bottom paint is wearing. If you decide to go with black bottom paint, it will age to a dark gray color in a short time, but that does not change the effectiveness.