A Complete Guide to Cleaning a Fiberglass Hull

Do you have a fiberglass hull on your boat? Though an incredibly tough and practical material, it’s always taking a beating from sun, salt, and waves. Over time, that once-glossy finish can start looking dull and chalky. Don’t worry—with the right approach and some elbow grease, you can restore your hull to its former glory. Read on for a complete guide to cleaning a fiberglass hull!

What You’ll Need

Before diving in, gather your supplies. You’ll want a good marine cleaner, microfiber cloths, a soft-bristled brush, and plenty of fresh water. For stubborn stains, grab some oxalic acid cleaner. If your hull looks really weathered, you might need polishing compound too.

Step-by-Step Cleaning Process

Start by rinsing the entire hull with fresh water to remove loose dirt and salt. This gets most of the grime out of the way in the first step, and it also prevents the sediment from scratching the hull when you start scrubbing.

Next, work from top to bottom using your marine cleaner. Spray a small section, let it sit for the recommended time, then scrub gently with your brush. The key word here is gentle—fiberglass can scratch if you’re too aggressive.

For those stubborn yellow or brown stains that seem impossible to shift, oxalic acid is your friend. Mix it according to the package directions and apply with a brush. Let it work its magic for about 10 minutes, then rinse thoroughly. Always wear gloves and work in a well-ventilated area when using acid cleaners.

If your hull has that chalky, faded look, you’re dealing with oxidation. This happens when UV rays break down the gelcoat over time. To remove oxidation from fiberglass, you’ll need to step up your game with a polishing compound. Apply it with a microfiber cloth using circular motions, working in small sections. This process takes patience, but the results are worth it.

Finishing Touches

Once you’ve cleaned and polished, rinse everything thoroughly with fresh water. Let the hull dry completely, then apply a marine wax or sealant. This protective layer slows future buildup, discoloration, and oxidation, making your next cleaning session much easier.

Keep It Clean

Regular maintenance beats major restoration every time. A quick rinse after each outing and a thorough cleaning every few weeks will keep your hull looking sharp. Plus, you’ll catch any issues before they become big, expensive headaches.

With this complete guide to cleaning a fiberglass hull, you can keep yours looking pristine and ready for whatever adventures await on the water!