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A Guide to Boat Fiberglass Care: Cleaning, Oxidation Removal, and Polishing


My Grand Banks 32; not bad for 35-year-old gelcoat. It took me a whole day from start to finish to get the boat to this level of gloss.


I know I have covered looking after gelcoat before, but this is the perfect time for a recap now that winter is just around the corner and many boats will be getting hauled.

Proper fiberglass care is essential to keep your vessel looking its best and ensure its longevity. This guide will walk you through the necessary steps, tools, and materials for cleaning removing oxidation through wet sanding, and compounding, polishing, and waxing your boat's fiberglass surfaces. Whether you're a seasoned sailor or a novice boat owner, this comprehensive guide will help you maintain your boat's pristine appearance.

Tools and Materials Required

Before you begin, gather the following tools and materials:

Pressure Washer: A high-quality pressure washer helps remove dirt and grime efficiently.

Soft Bristle Brush: Use a soft brush to scrub the fiberglass without scratching the surface.

Boat Soap: Choose a boat-specific soap that's gentle on fiberglass.

Bucket: For mixing and applying boat soap.

Hose: To rinse off soap and debris.

Microfiber Towels: For drying the boat and for later steps.

Wet/Dry Sandpaper: Choose various grits (e.g., 600, 800, 1000, 1500, and 2000) for wet sanding.

Water Sprayer Bottle: To keep the surface wet while sanding.

Dual Action Polisher/Buffer: A professional-grade buffer like the DeWalt 9-inch polisher is ideal.Manufacturer link here

Compounding Pad: Use foam or wool pads for compounding.

Polishing Pad: Foam or wool pads are suitable for polishing as well.

Marine Compound: Opt for a high-quality marine compound like 3M Super Duty Compound.

Marine Polish: A top-rated marine polish such as Meguiar's M4516 is a great choice.

Marine Wax: Select a marine wax like Collinite 925 for long-lasting protection.

Applicator Pads: Soft foam applicator pads are necessary for applying compound, polish, and wax.


Before applying any compounds or polishes, it is essential that the boat is clean, or you'll just be rubbing dirt into the gelcoat.

Start by rinsing the boat with a pressure washer to remove loose dirt and debris.

Mix boat soap with water in a bucket and gently scrub the fiberglass surface with a soft bristle brush.

Rinse thoroughly to remove all soap residue.

Dry the boat using microfiber towels to prevent water spots.

Removing Oxidation by Wet Sanding: only needed if the boat is heavily oxidized.

Soak the sandpaper in water for a few minutes.

Begin with the highest grit sandpaper (e.g., 2000) and only use a coarser grade if absolutely necessary.

Sand the oxidized areas in a circular motion.

Keep the surface wet with a water sprayer bottle.

Rinse and dry the boat thoroughly.

Compounding, Polishing, and Waxing

Attach a compounding pad to your dual action polisher/buffer.

Apply a small amount of marine compound to the pad.

Work in small sections, applying moderate pressure and moving the buffer in a side-to-side and up-and-down motion.

Wipe off excess compound with a microfiber towel.

Switch to a polishing pad and apply marine polish in the same manner as compounding.

After polishing, apply marine wax using applicator pads in circular motions.

Allow the wax to haze, then buff it off with a clean microfiber towel for a brilliant shine.

Foam Pads vs. Wool Pads

Foam Pads: Foam pads are gentler on the surface and are ideal for light compounding, polishing, and waxing. They are less aggressive and are suitable for maintaining well-maintained fiberglass.

Wool Pads: Wool pads are more aggressive and are often used for heavy compounding to remove deep oxidation and scratches. They can be followed by foam pads for polishing and waxing.

In conclusion, maintaining your boat's fiberglass requires careful attention and the right tools and materials. Regular cleaning, wet sanding for oxidation removal, and compounding, polishing, and waxing will keep your boag stunning and protect it from the elements. With the right products and techniques, you can ensure your boat remains a source of pride for years to come.

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