Ten cleaners from seven manufacturers. Top row, left to right: Meguiar’s Vinyl and Rubber Cleaner and Conditioner, 3M Marine Cleaner and Restorer, Marine Spray Nine, Marykate Ultra Vinyl Cleaner, 3M Marine Outdoor Vinyl Cleaner. Bottom row, left to right: BoatLIFE Vinyl Cleaner, Spray Nine Marine Once Over, Star brite Vinyl Cleaner and Polish, Meguiar’s Heavy Duty Vinyl Cleaner, West Marine Vinyl Cleaner.

Some marine cleaning products are flat-out unnecessary. We learned this last month when we tested water spot removers. A simple solution of vinegar and water was capable of doing the same job as the brand-name products. It’s a different story this month, though. Vinyl cleaners are necessary—and they do a much better job at removing mildew, grease, and grime than your favorite household cleaners.

Your boat is filled with vinyl, especially cruising boats that pack vinyl-covered seat cushions into every nook and cranny of the boat. A couple of weeks—perhaps even days—of inattention, and an outdoor settee can become plagued with nasty mildew. …