Last Updated: February 16, 2026
Quick Recommendation
How to Fill a Hole in Fiberglass
- Small holes (screw/bolt size): Use marine epoxy with filler to seal and restore strength.
- Larger holes: Rebuild with fiberglass cloth and resin in layers before fairing and finishing.
- Prep properly: Grind or bevel the edges, clean thoroughly, and ensure the surface is dry before applying resin.
- Bottom line: Structural repairs require fiberglass reinforcement first, then fairing and finishing with gelcoat or paint.
Tip: If the surrounding fiberglass feels soft or wet, address moisture issues before sealing the repair.
When you are trying to repair a small hole in fiberglass, the best type of product to use is a premium epoxy. This will insure a proper repair and will not allow for shrinking of the material and create a water tight seal.
We recommend the Hawk Epoxy Kit. It contains the epoxy resin, catalyst and filler for the job. Watch the video below to see the steps needed to perform a small hole repair.
How to sand fiberglass for paint
Whether you’re trying to give your boat a new paint job or just touched up a few scratches, properly sanding fiberglass is an important step to ensure a smooth, even finish. Here’s a quick guide on how to sand fiberglass for paint:
- Start with a coarse grit paper (40-60) to remove any existing paint or surface imperfections.
- Progress to a medium grit paper (80-100) to smooth out the surface.
- Finally, use a fine grit paper (200+) to achieve a glass-like finish.
- For best results, wet sanding is recommended – simply soak the sandpaper in water for 10-15 minutes before use. This will help to prevent deep scratches and gouges.
How to prep fiberglass for paint
One way to do that is to make sure the fiberglass is properly prepared for painting. Here are some tips for prepping fiberglass for paint:
First, wash the area with boat soap and a soft brush. This will remove any dirt or grime that could prevent the paint from adhering properly.
Next, sand the area with fine-grit sandpaper. This will create a smooth surface for the paint to adhere to.
Finally, wipe down the area with a tack cloth to remove any dust from sanding.
If you have additional questions feel free to reach out to the Botton Paint Store technical team 888-505-2313.