How to Repair a Fiberglass Boat?

Last Updated on October 1, 2022

If you own a fiberglass boat, sooner or later you’re going to have to repair it. Fiberglass is strong and durable, but it’s not bulletproof. Sooner or later something will happen that requires a little bit of repair work. 

Don’t worry, though repairing a fiberglass boat is actually relatively easy. 

Fiberglass boats are a popular option for boat buyers because of their light weight, durability, and easy customization. However, repairs to fiberglass boats can be tricky and challenging if you’re not familiar with the material.

In this article, we’ll walk you through the process details.


How Do You Fix Fiberglass Damage on a Boat?

Fiberglass boats are popular because they are durable and require little maintenance. However, fiberglass is not invulnerable to damage. 

Over time, the gel coat that protects the fiberglass can become dull and stained, and the fiberglass itself can become scratched or cracked. 

While some fiberglass damage can be repaired with a little elbow grease, more serious damage may require the help of a professional. 

If you are lucky enough to catch the damage early, you may be able to sand it down and buff it out yourself. 

However, if the damage is more extensive, you will need to use a putty knife to fill in the cracks, then sand and repaint the surface. 

No matter how small the repair job may be, it is important to take care of it as soon as possible to prevent further damage from occurring.

Assuming you are asking how to fix small holes or cracks in a fiberglass boat:   

Supplies Needed: 

  • Fiberglass cloth  
  • Resin (polyester, epoxy, or vinyl ester)
  • Hardener (for resin)
  • Mixing sticks  
  • Measuring cups
  • Sandpaper (80 and 220 grit)
  • Paintbrush or roller    


  1. Clean the surface around the damage with acetone or alcohol. This will help the resin to adhere properly.   
  1. Cut the fiberglass cloth into strips that will fit over the hole or crack, plus an inch or two on each side.
  1. Mix together the resin and hardener according to their instructions. Use a mixing stick to stir them together until they are fully combined. This is important, otherwise, the repair will not be as strong as it could be.   
  1. Brush or roll on a layer of resin over the damaged area then lay down a strip of fiberglass cloth over top. Repeat this process until all of the damage is covered make sure to overlap each layer of cloth by about half an inch.   
  2. If you are using polyester resin: once all of the damage is covered, brush on another layer of resin over the top of the entire repair area and let it cure for at least 24 hours before sanding smooth and painting over top.
  3. If you are using epoxy resin: once all of the damage is covered, leave it to cure for at least 12 hours before proceeding to the next step 
  4. If you are using vinyl ester resin: once all of the repairs have been made, brush on a final layer of wetted-out matting, cover with plastic sheeting and let cure for 24 hours minimum prior to proceeding further.
  1. Using 80 grit sandpaper, feather edges around the entire repair area until smooth
  2. Wipe away any dust created from sanding
  3. Using 220 grit sandpaper, lightly go over the entire repair area. 

Can a Fiberglass Boat Hull Be Repaired?

If you have a hole in your fiberglass boat hull, the first thing you need to do is clean the area around the hole. You want to make sure there is no debris or dirt that will prevent the repair materials from bonding properly. Once the area is clean, you can begin repairing the hole.

There are two ways to repair a hole in a fiberglass boat hull: with a patch or with filler. A patch is a piece of fiberglass cloth that is saturated with resin and then placed over the hole. The patch will bond with the surrounding hull and reinforce the area around the hole.

A filler is a putty-like material that is used to fill holes and cracks. It can be sanded smooth once it dries and then painted over. Whether you use a patch or filler, you will need to apply resin to both sides of the repair (inside and outside of the hull).

This will ensure that water cannot get through the repair and cause further damage. Applying resin can be done with a brush, roller, or spray gun. Once all of the repairs have been made and allowed to dry, you should sand down any rough edges and apply new paint as needed.

What Do You Need to Repair a Fiberglass Boat?

If you’re lucky enough to own a fiberglass boat, you know they require special care to keep them looking shiny and new.

Over time, the gel coat on your boat will become dull and scratched, and if you don’t take steps to protect it, your boat will eventually lose its luster. Luckily, repairing a fiberglass boat is not as difficult or expensive as you might think.

With a little elbow grease and the right supplies, you can make your fiberglass boat look new again.

To repair a fiberglass boat, you will need

  • Abrasive pads (for sanding)
  • Sandpaper (various grits)
  • Polishing compound
  • Wax
  • Rags or towels
  • Bucket
  • Water hose
  • Sponge 

First things first,

Before you start any repairs on your fiberglass boat, it’s important to clean the surface thoroughly. Use a sponge or rag to wipe away any dirt, grime, or debris that has gathered on the hull.

Once the surface is clean, wet the entire area with a water hose. This will help to loosen any stubborn dirt particles that are stuck on the gel coat. 


Use an abrasive pad and sandpaper (starting with coarse grit and working your way up to fine), and begin sanding away at any scratches or imperfections in the gel coat.

Be sure to sand evenly across the entire surface – you don’t want any “low spots” that could lead to further damage down the road. once all of the scratches have been removed, it’s time to polish the hull. 

Apply polishing compound evenly across the surface using a rag or towel; then buff away until you achieve a shine. 


Apply wax over the entire hull for protection against future wear and tear.

How Do You Fix Gelcoat on a Fiberglass Boat?

When Gelcoat on a fiberglass boat starts to show signs of wear, it’s time to take action and restore it. There are several ways to go about this, but the most important thing is to use the right products and follow the directions carefully. The first step is to clean the area that needs to be repaired.

This means removing all dirt, grime, and oxidation. Once the surface is clean, you’ll need to sand it lightly with a fine-grit sandpaper. Be sure to remove all dust before proceeding.

Next, apply a gel coat repair kit according to the manufacturer’s instructions. These kits usually come with everything you need, including resin and hardener. Mix these two components together thoroughly before applying them to the damaged area with a brush or roller.

Once the repair kit has been applied, allow it to cure for the amount of time specified in the instructions. After it has cured, sand the area smooth and apply a new coat of gel coat using the same process as before.

How to Repair a Fiberglass Boat?

How to Repair Fiberglass Boat Hull from the Outside?

If you have a fiberglass boat, you know that they are extremely durable and can last for many years with proper care. However, over time, even the best-cared-for boats will start to show signs of wear and tear. One common issue is hull damage.

While it may seem daunting, repairing hull damage on a fiberglass boat is actually not that difficult – especially if you catch it early.

First, you’ll need to clean the area around the damaged area thoroughly. This will help ensure that the repair adheres properly.

Next, use a utility knife or sandpaper to remove any loose fibers or paint from the damaged area. Once you’ve done that, apply a generous amount of resin to the area and spread it evenly with a putty knife.

Now comes the waiting game letting the resin cure. Depending on temperature and humidity levels, this can take anywhere from 24 hours to several days. Once the resin has cured, sand down the area until it is smooth and level with the rest of the hull.

Finally, apply a new gel coat or paint to match your boat’s existing finish. That’s it!

By following these simple steps, you can easily repair hull damage on your fiberglass boat without having to take it out of commission for an extended period of time (or spending a lot of money).

Structural Fiberglass Repair

If you have a damaged fiberglass structure, don’t despair! While it may seem like a daunting task, repairing fiberglass is actually quite simple. Here are the basics of structural fiberglass repair:

First, you’ll need to assess the damage and determine what needs to be repaired. If the damage is extensive, you may need to replace some or all of the damaged panels. However, if the damage is relatively minor, you can probably get away with patching up the affected area.

Once you’ve determined what needs to be done, it’s time to gather your supplies. For small repairs, all you’ll need is some epoxy resin and some reinforcing fabric (fiberglass cloth or matting). For larger repairs, you may also need some sheets of fiberglass and/or some polyester resin.

Now it’s time to start repairing! If you’re just patching up a small area, simply mix up some epoxy resin and spread it over the affected area. Then lay down a layer of reinforcing fabric and allow everything to cure.

For larger repairs, follow the same basic process but use sheets of fiberglass instead of fabric patches. Once everything has cured, sand down any rough edges, and your repair should be good as new!

Fiberglass Boat Repair Kit

For anyone that owns a fiberglass boat, it’s important to have a repair kit on hand in case of any damage. Although fiberglass is a strong and durable material, it can still be susceptible to cracks and holes. A good repair kit will come with all the necessary materials and instructions for properly fixing any damage.

The first step in repairing fiberglass damage is to clean the area around the damage with soap and water. This will help to remove any dirt or debris that could prevent the repair materials from adhering properly.

Once the area is clean, you’ll need to sand down the damaged area to create a smooth surface for the repair materials.

Once the area is prepared, you can begin applying the repair materials according to the instructions included in your kit. In most cases, this will involve using a putty or resin compound which will need to be left to cure for some time before being sanded down and painted over.

With proper care and attention, your fiberglass boat should be as good as new in no time!


If you’re the proud owner of a fiberglass boat, you might be wondering how to keep it in tip-top shape. While fiberglass is a durable material, it’s not invincible.

Over time, your boat may start to show signs of wear and tear. Fortunately, repairing a fiberglass boat is relatively simple. In most cases, all you need is some epoxy resin and a little elbow grease.