Just painted my hull for the lower Hudson (salt)
water environment and launched. I have been using an ablative paint that slowly flakes off in the salt environment for a few years and it always comes out looking great after a power washing. I put on 3 new coats of the same paint but that is just me. My boat once came out with a nice beard several years ago because of an inadequate job I had done on it with a different paint that shall remain nameless so certain members of this forum (Waffle) do not get upset (VC-17 - better in freshwater). If your boat has an ablative or soft hull paint on it then if you rub it with a dry or wet white rag and a good bit of color comes off on the rag then it is probably a soft or ablative paint. This paint seems to work well in salt water, is recommended by Practical Sailor among others and was on sale at WM (west marine) for well under $100/gal earlier this spring (WM CPP Ablative - $35 mail in rebate, which I have not yet received - final cost nearly $60/gal).If your hull has paint chips forming that will easily pop off then you have a hard paint (which I doubt if your PO had any salt in his blood) and I have little to say about that except that I hope you like sanding and scraping sloping surfaces.If the hull looks good, try to get away with just a mild hand sanding with say 120 - 150 grit paper. It is a good idea to lightly sand the entire underwater surface before you do the wipe down. I always wipe my hull down with Interlux thinner #216 but some say you should use the #202 (fiberglass solvent - inhaled too much of this stuff, cant remember the #) with a copious amount of rags to get all the stuff that is about ready to fall off completely off the hull, before I start painting (put masking tape on water line before all of this of course).1 gallon of anti-fouling paint covers the hull of 27' Tartan (which has a rather long keel) almost twice so for your 25 footer that would be an easy 2 coats per gallon. You might be able to get away with one more season without doing anything. As soon as the hull comes up with mussels and starfish on it and a seaweed beard you will want to have the insurance of another coat of hull paint.I would recommend buying a gallon of hull paint and either putting one coat on before you launch this season, while saving the last half gallon for the next coat, or, just giving your hull 2 coats and a good paint job that will hopefully last a good while in salt water. Your hull is after all the part of your boat that you want to keep water out of by any means available. I like doing the hull job on my old 1967 boat myself as I get to see every square inch of her under water line up close and personal. Am I being anal about this?If I were Huck Finn I would want to construct a raft that floated with me and Tom and supplies and was safe. But I am not Huck Finn and I have a fiberglass boat now and am resigned to the fact that I do have to paint the bottom nearly annually to keep it from becoming part of the underwater flora and fauna.Good luck getting her in the water.