Re: roof coating
Reply #15 –
That's a good point, and the answer has more to do with personal preference. So, polyester gelcoat is the original coating for the roof. The advantage to using more gelcoat rather than paint is that it chemically bonds with the original coat and becomes, essentially, a new roof. If your original gelcoat is somehow eroded away to the point you can see the fiberglass substrate, no question, use gelcoat. Gelcoat has perfect water resistance, and the thickness of the coating means it'll be very unlikely to need redone again. If damaged by impact or abrasion, very easy to do a 100% fix. On working boats, a gelcoat deck is far more durable than painted.
Paint, in contrast is a coating which depends on surface adhesion. Nowadays, most auto paints are known as 2-pack, meaning they are catalyzed and shot using dry air, respirators or outside air source. They can be shot outside, but expect some defects. The 2-pack usually means an acrylic paint with a urethane hardening agent and specific thinners for ambient temp. They require some expertise to get right but it's possible to roll some of them on. They are expensive and have limited shelf life. They are very difficult to repair, and expensive to do as you typically have to buy all the components of the paint. Just plain acrylic paint, air dried, with no hardener, what we used to call "enamel paint' generally does not cure hard enough to suit most folks. The stuff I've used lately has required added dryers to make it cure reasonably well.
So, paint takes a fair amount of prep, equipment and $. It also takes awhile to dry. Your results depend on your expertise, there's no easy way to fix mistakes.
Gelcoat, like paint, requires a properly prepared surface. Waxes need to be removed. Generally, wiping it down with acetone and a rag takes care of prep assuming there's no other coating (Polyglow or the like). The gelcoat is catalyzed per mfg reps for ambient temp, and rolled on using a long handled smooth roller, walking and rolling from front to back. It cures quickly, so it's necessary to keep a move on with it. Drips, runs, ridges can be sanded smooth if necessary. Probably take 2 gallons to do a FT roof. It's possible for things to go south if you aren't familiar with materials or process so best to have some knowledgeable help on hand.
Painted roof will probably look slicker. Gelcoat roof will last longer, but will show some texture if rolled. Personally, if I were painting a roof I'd look for some of the "roll and tip" two part enamels used for boat hulls. That at least would get you out of the hassle of spraying. A paint advantage would be the ability to paint shrouds, vent covers etc.
Most likely more than you wanted to know.
Topic: roof coating