How to repair a fibreglass boat hull
Instapatch is made from glass reinforced plastic, the same kind of material as most fibreglass hulls. It can seal cracks, chips and small holes, and cures hard in daylight in 15 to 45 minutes.
When to get help: For large holes, or damage that could affect the strength of the hull below the waterline, have the boat checked by a boatyard or marine surveyor first.
What you'll need
- Instapatch Standard patches big enough to cover the damage with room to spare. The order wizard will suggest a size.
- UV Curing Primer and a brush. It's optional for small surface repairs and recommended for anything structural.
- Scissors or a sharp knife
- Gloves and protective clothing
- Surface cleaner or degreaser, and clean cloths
Before you start
- Take the boat out of the water and let the hull dry fully around the damage.
- Remove all wax and polish from the repair area. The surface must be free from dust, grease, waxes and loose material.
- Remove any loose gelcoat or flaking antifouling around the damage.
- Only open the patch when you're ready to use it. It can start to cure within minutes in daylight.
Steps
Clean and degrease the area to remove wax, polish and dirt, then let it dry.
Remove any loose gelcoat or flaking paint around the damage.
For a structural repair, brush on UV Curing Primer and let it dry fully.
Shape the patch with scissors while it's still in its packet.
Peel the release film from one side, press the patch on straight away, and mould it to the curve of the hull. Apply firm pressure all over.
If you want to sand and paint the repair, peel off the top film now for a matt finish. Leave it on for a gloss finish that can't be painted.
Leave the patch to cure in daylight. Keep pressing the edges down until it hardens, so the corners don't lift.
Cure timing for this surface
Outdoors, daylight cures the patch in 15 to 45 minutes, depending on how bright it is. In a covered boat shed, use a UV lamp or torch.
After the repair
Once it has hardened, the patch is waterproof and highly resistant to weather and UV. You can sand it and paint it to match. Check the repair before you put the boat back in the water.
Common questions
Once cured, the patch is waterproof, and hull repairs are one of its listed uses. For damage below the waterline that could affect the strength of the hull, get it checked first.
Yes, if you peel off the top film straight after applying the patch.
Common mistakes to avoid
- Patching a hull that hasn't dried out
- Leaving wax or polish on the surface
- Relaunching before the patch has fully hardened
- Patching over structural damage without getting it checked
Safety
Wear gloves and protective clothing, and only use Instapatch in a well-ventilated area. It contains polyester compound and styrene, which can irritate the eyes, skin and lungs. If it gets in your eyes, rinse them straight away with plenty of water and get medical advice. If it gets on your skin, wash it off with soap and water.
Storing spare patches
Keep unused patches on end in their original wrapping, somewhere cool, dry, dark and frost free. If a patch is very cold, warm it before use.