Thats an alkyd enamel, similar to Rusto or other implement paints....you should be able to thin it with acetone or spirits.......try wet sanding it in a small area after 24 hrs, if it doesnt gum up the paper, wet sand it and recoat a few times, you can also try running the foam roller over then next coat just before it starts drying, to smooth it out.
Home depot may try to tint it for you, tell them to use a tint for oil based enamel and if you can bring anything flat and small off the boat, they can color scan and match what you have now.....not sure if you have anything with the gel color on it left over. Or you can try sherman williams, they sell insulex i believe, and may be able to tint it for u using their color cards to get a close match.