Waterline paint help needed

[herewego]

Just wondering about where to stop my topside paint on a 191 Osprey I'm refinishing. The awlgrip and Interlux epoxies I've been looking at specify above the waterline only, yet I see boats painted on the sides and transom down below the waterline along the chine line like the photo attached here. Is it OK for the topside paint to sit below the water?
I plan to trailer the boat, but there may be times I leave it in the water for a few days.

[herewego]

Have not heard back from Awlgrip tech but Interlux emailed me back and said all topside paints should not be below the water line, as they will peel and blister.

Still interested to hear from any owners who have painted down to the chine line of their boats. So many of the rebuilds I see are painted to below the water line and wondering if over time they have seen problems.

[mshugg]

Are you keeping the boat in the water or on a trailer?  I believe the consensus is that top sides paint is fine below the waterline as long as the boat is trailered.  Even a few days, like a Keys trip for example is fine.  If you keep the boat in a slip, then an epoxy barier coat and bottom paint is the best approach. 

As for identifying the waterline float the boat and use a grease pencil to mark waterline.  Your bottom paint should extend an inch or two above the static water line.

[herewego]

Thanks. Think I'm going to use the polyurethane topside paint a couple inches above the waterline. I'll do the bottom in Interlux VC epoxy bellow the waterline.

While I'm here, previous owner used 5200 behind the jack plate and when I took it off, the gelcoat came with it. Would it be best to recoat the bare fiberglass with gelcoat or just fill and fair it with expoxy putty? The spot with no gelcoat is about 18 inches square now that I have scraped and sanded the area. Anyone think that is too big to fill with anything but gelcoat???

[doug mayer]

Doing gelcoat is a bear, and if the work you are doing will be behind a jackplate, use epoxy.  The only thing is that, epoxy exposed to sun will not endure, so any in the sun needs paint.