Repair holes and cracks above the waterline

Would you like to repair cracks, scratches or holes in your polyester boat? Then read this article quickly! We would like to explain to you what you can do to repair cracks, scratches or holes in the hull of your polyester boat, among other things, so that you can then re-coat the boat. Below, we go through the repair of the upper water part of the hull of the boat step by step. We also have a step-by-step guide for repairs below the waterline.

Manual for repairing cracks and holes in your polyester boat


The quantities of supplies listed below depend on the size of your boat's hull and, of course, the damage to it. If in doubt, contact us for tailor-made advice. Did you order too much? No problem, you can return unopened packages free of charge!

For this repair, you will need various raw materials and tools. If you order the items below from us, they are often dispatched the same day. So you can get started on the repair quickly!

Raw materials:


Step 1. Check

The first step in repairing damage to your boat's hull is to check where the damage is. Think of cracks, scratches or holes from removed equipment (such as winches, blocks, etc.).

Step 2. Beveling Holes, Cracks and Scratches

You can bevel cracks and scratches with a sander or angle grinder with a 4:1 flap disc ratio. Larger holes can be chamfered in the ratio of 8:1. When a hole is several centimeters in size, the hole is often beveled and sealed on both sides.

After grinding out, check that cracks are not deeper than expected. Wet the sanding area and wipe it dry again. In a crack, water will stay longer and become visible again. If this is the case, you can grind out any cracks even deeper.

For large holes, seal the back with a plate covered with a piece of tape so that the epoxy does not stick to it. If the back of the hole is not accessible, stick the plate through the hole and hold it in place with a piece of wire or a roller bracket.

Step 3. Sealing the small holes

Before you can start working with epoxy, you need to clean and dust the hull and all the parts to be repaired. Once you have done this, you can start making the epoxy. While working with epoxy, wear disposable nitrile gloves.

Small holes, no more than 1 cm in diameter, can be sealed with a mixture of epoxy and cotton fibre. By mixing cotton fibre through the epoxy, you get a paste. You can use this paste to seal the hole, using a flexible spatula. It is necessary to seal the hole to the surface, there may be a small edge (as long as it is sealed). 

Step 4. Sealing large holes and cracks with epoxy and glass fabric

In this step, we are going to laminate the larger holes with glass fabric and epoxy. Start by cutting pieces of glass fabric from large to small, according to the size of the crack or hole. Start laminating the smallest piece of glass fabric using a brush and prepared epoxy. Laminating with epoxy is done as follows:

  • Wet the substrate with epoxy resin (use a round brush for this). 
  • Press the smallest piece of glass fabric into the epoxy. 
  • Then press larger pieces of glass fabric into the epoxy and wet them again with resin. 
  • After each layer, you should vent the glass fabric with a vent roller.

Build up several layers in this way, until the fabric is level with the surrounding surface. Now let the epoxy cure. 

For holes that are completely through the hull, once cured on the inside, the temporary plug can be removed and, following the above method, the spot can also be sanded and laminated at an angle from the inside. The strength is now fully restored.

After working with the epoxy, clean the vent roller with acetone and an unused brush. This will prevent the epoxy from curing in the roller and rendering the roller unusable.

Step 5. Follow-up

After you have sealed all the holes, you can sand and tighten the whole thing with epoxy putty. When the hull is completely tight, you can paint it with our DD lacquer. Do you have any questions about the products in this article or how to repair damage to the hull of your boat? Feel free to contact ourcustomer service team via email, phone or live chat!