OT , STOW. the deal in my area on this bottom painting question is quite strange. Even though I am at the headwaters (spring fed) of my river that runs out to the Gulf of Mexico (so the water is tidal but still all but totally fresh), we still get some serious barnacles on any thing like PVC, or plastic that stays in the water any length of time. So, since my boat is only 26' long, I just lift it out of the water and store it that way with a lift on my dock.
My guess is that water chemistry is different everywhere and so would be the types of little barnacle buggers that could get on our boat's hulls.
Sounds like you have a pretty good area in regards to the question of this problem. I would suggest if you do not bottom paint, then at the least, keep an eye on what is happening below the water line, you prolly would see something in its beginning stages.
BTW, it appears you have already arrived at the point in yachting I am still strivng for--that is, to have a boat too large to lift out of the water--g