I redid my '81 h16 this spring - I had never really looked close at the hull underside before. It was pretty bad. There were fibres coming out of the keel on one hull, a few holes punched on the inside on the other. Wanted to get rid of the gonzo yellow-orange color anyways, so it was time to redo the hulls.
Sanded areas around patching and nick filling with 80 grit, and used West System epoxy with microballons to fill. I'm used to working with polyester resins and fillers (stinky stuff) and I really like the epoxy for no smell and excellent adhesion, and mixing your own stiffness of filler is neat, and the pumps make it so clean. The downside is cure time - you can mix up a batch of polyester filler with extra hardner and sand it in 10 minutes - you have to wait til next day with epoxy, so 4 or 5 fill layers can take a week. Once filling was contour sanded and feathered, 3 neat barrier layers were rolled on, giving a day for each to cure (shoulda done one after the other, same day). Then both hulls got sanded all over with 120 grit (shoulda stuck with 80) in prep for primer. The grip pattern on top of the hulls is difficult to get a tooth on with the sandpaper, I probably should have used a sidegrinder and shaved it off.
Epoxy primer is nasty smelling stuff - use a carbon mask. Rolls on as thick as you might want to make it - did 2 coats. Lightly sand after each to get rid of runs or ridges. It's a bugger getting under the lip, used those small black foam brushes, but have to work quickly as the epoxy eats the foam. Then the 2 part liquid polyurethane - 3 coats, again lightly sanding between to get rid of imperfections. There was a bit of dust flecks that collected on the surface making it slightly stippled, really only felt by hand rather than seen but as the paint has cured for a few months those have disappeared (from wear?). Cure for a week before reassembling the boat.
I must say the paint looks awesome for a roller job, thank you wife for the wonderful job of tipping and rolling the paint. Very slippery, though, on the surface of the hulls, which is why I would recommend (if painting with 2 part LP) shaving off the grip top pattern and using some adhesive traction pad. This paint is tough stuff! We still beach our cat, on very coarse sand and scrape by rocks and the bottoms still look new! The paint will chip under moderate impact (like a wrench falling on it) but that may be due to not sanding with coarser grit before primer for a good mechanical bond.
