What grit sandpaper to use on fiberglass boats?

Release Date:2023-04-19 10:21
Fiberglass boats are a popular choice among boaters due to their durability and low maintenance needs. However, over time, the fiberglass may develop scratches, cracks, or other forms of damage that require repair. When it comes to repairing fiberglass boats, sanding is often necessary. But what grit sandpaper should you use?

The answer depends on the task at hand. Let's take a look at the different grits and their uses:

60 to 80 grit: Use this coarse grit to remove paint, gel coat, or other heavy coatings. It is also suitable for shaping and fairing.

100 to 150 grit: This medium grit is ideal for smoothing out the surface and removing any remaining coatings.

220 to 400 grit: Use this fine grit for the final sanding before applying a new layer of gelcoat or paint. It will ensure a smooth and even surface.


It's important to note that sanding fiberglass can produce fine dust particles that can be harmful when inhaled. To protect yourself, wear a respirator mask, safety goggles, and gloves. Also, make sure to keep the work area well-ventilated.

In addition to choosing the right grit, it's also important to use the sandpaper properly. Always sand in a circular or back-and-forth motion, and avoid applying too much pressure, as this can damage the fiberglass. Rinse the surface with water between sanding passes to remove any debris and to see how much progress you've made.

In conclusion, when it comes to sanding fiberglass boats, use 60 to 80-grit sandpaper for heavy coatings, 100 to 150-grit for smoothing, and 220 to 400-grit for the final sanding. Remember to wear protective gear and sand properly to achieve the best results.
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