When to Use Fibreglass Mat on a Wooden Speargun

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When Do I Use Fibreglass Mat on a Speargun?

Fibreglass mat, when combined with a suitable resin, can be a real asset for strengthening and repairing underwater wooden spearguns. But it’s not always necessary for every build. Here’s how to know when reinforcement is required for maximum durability.

Why Use Fibreglass Mat on Wooden Spearguns?

Fibreglass mat paired with resin is perfect for areas exposed to significant stress or for repairing existing cracks and weaknesses in the wood. The mat forms a strong composite layer, distributing mechanical loads and greatly improving impact resistance—qualities essential for underwater use and rough handling. This additional layer helps your speargun stay reliable and watertight even when subject to repeated tension or knocks during dives.

Where and How to Apply Fibreglass Mat

Focus reinforcement on high-stress zones such as the barrel, around trigger mechanisms, or mounting points where wood may be thinner or previously damaged. To apply, ensure all wood surfaces are clean, dry, and properly sanded. Layer the fibreglass mat over the target area, saturate with an appropriate resin—such as the Resin Fibreglass Repair Kit—and allow to cure fully. For total waterproofing, additional coatings with a specialist wood epoxy can be applied atop the reinforcement.

When This Matters Most

When repairing visible cracks or splits in a wooden speargun
After impact, or if the speargun is repeatedly stressed at certain points
If you notice previous waterproof coatings have worn thin, especially on older spearguns

Related guides

How Do You Resin An Underwater Wooden Speargun

Adding fibreglass mat is a sensible choice for anyone aiming to strengthen or repair an underwater speargun. For more advice on sealing and maintaining wood below the waterline, see our full speargun resining guide.