My DS came painted and the receipt that the previous owner included is dated 10 years ago and identifies the paint as "International enamel". The colors indicate that these were the paints used for deck and inside of the hull. Unfortunately I find that those descriptions don't match up with anything I can find on the web, which is a shame, because they've held up quite well until now.
"International" which seems to be identical to "interlux" nowadays makes a line of Yacht enamel paints, but not in the colors. So I'm not sure what these paints are (they also were satin, not glossy, and most of the paints they now advertise seem to require a flattening agent, which would have shown on the receipt).
There are a few areas where I've scraped off the paint by dragging something sharp and heavy, but they are localized, the worst being inside the motor well, which I use to store misc items (like rocks the younger passengers have collected on the beach).
There's some deck area at the front, where I had insufficient tarp coverage the first few years - that has weathered a section of the paint. And, as of this year, there are areas on deck where the paintis beginning to flake, so it's time to think about redoing the job.
Still holding well on the seats, though.
For the places inside the hull where the floorboards rest, they had ground through to the laminate at the contact spots. There, I've used a clear (transparent) gelcoat patch kit to add a tough layer and seal the laminate again. I didn't bother painting over those spots. (Incidentally, where the patch material covered adjacent paint, it's bonded nicely to the paint, so this looks like something one could use even to apply over paint to help protect such spots from rubbing through - it's transparent, so you simply see what's underneath).
This is how the boat's been stored.
I've not had a lot of standing water problems or ice cubes, despite the picture, but the paint in the lowest part of the hull looks no different than higher up on the inside.
So, overall, it's possible to get durable paint.