My boat is in Puget Sound year round. I rolled on UltraKote last fall. You can burnish (polish) UltraKote (and probably Trinidad too) to a very smooth finish using sandpaper and burlap. Start with a prepped (cleaned dried, sanded, SMOOTH) bottom and roll on a few coats (spraying is better but nasty.) Find the rollers that give you the smoothest finish to begin with (we found the cheaper the roller the better the finish - can't explain that one) as this will mean less burnishing is required. We went with UltraKote because that was used previously on our boat and it holds up to scrubbing well. The newest version has a biocide now too. Don't know why Trinidad would be hard to apply - I've never used it.