How to repaint a fibreglass boat (step-by-step)

Whether your current paint job is looking tired or you’re looking to change the colour of your vessel, repainting a fibreglass boat is a task that requires careful preparation and plenty of patience.

Here, we share a step-by-step guide on how to do it, from gathering your materials and preparing the surface to priming the area and applying the topcoat.

What you need to repaint a fibreglass boat

There are many important items you’ll need to complete the job. Gathering what you need in advance will ensure that you can seamlessly complete each of the required steps. Your boat painting essentials include: 

• Commercial solvent
• Degreaser
• Sandpaper/power sander
• Scraper
• Brush
• Foam rollers
• Primer
• Masking tape
• Paint

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Repainting a fibreglass boat: step-by-step

There are five main steps to complete. Each step is important to ensure a smooth, durable finish, so don’t be tempted to skip any of the following stages.

1. Prepare the surface

Preparing the surface of your fibreglass boat will help you to apply the paint smoothly. Use a mixture of ammonia and water to clean the surface, followed by a commercial solvent that will remove the layer of wax covering the gel coat. This wax can prevent the paint from adhering to the surface, so it’s essential that it’s removed before priming. You could also opt for a combined solvent and cleaner to complete this step.

2. Sand the fibreglass

The next step is to sand the fibreglass using sandpaper. If you are painting fibreglass that hasn’t been previously painted or the current paint job is in good condition, sand the entire surface to create a texture that the primer will adhere to. If the existing paint job shows signs of flaking or degradation, it will need to be removed before sanding. Once sanded, use a degreaser to remove any remaining contaminants and residues. Take your time on this step, as a durable finish requires a well-prepared surface.

3. Repair any surface damage

While sanding the surface of your fibreglass boat, keep an eye out for any damage that will need to be repaired before priming. Small dents and dings in the surface can be fixed using an epoxy filler or putty. Once this has been set, it will need to be sanded using sandpaper or a power sander to achieve a smooth finish.

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4. Apply primer

Primer is used to ensure your chosen paint adheres to the fibreglass surface. Your boat will need to be primed if you’re applying paint to bare fibreglass or are unsure of the paint that was used previously. If you’re using the same paint as the last time you painted your boat, you won’t necessarily need to use primer. If in doubt, prime the surface to achieve the best results.

Using a high-quality foam roller or brush, apply a thin, consistent layer of primer evenly over the entire area you’ll be painting. You should opt for a primer that will work well with the paint colour you’ve chosen – for example, a light-coloured primer to sit beneath white paint. One coat of primer can be sufficient, but it’s best to apply two where possible. Refer to the manufacturer’s instructions for additional details.

5. Paint the boat

The final step is applying the paint. Ensure that your primer layer is completely dry and thoroughly inspect for any dents or blemishes that may have been missed and require filling. The surface needs to be as smooth as possible to ensure a successful application of the topcoat. Clean and degrease the surface again, then thoroughly stir your paint. Pour the required amount into a tray.

Repainting a boat is easier with two people, as the first person can apply the topcoat with a roller while the other goes over the surface with a brush to ensure an even finish. However, this task can be completed on your own. Apply two coats of paint, leaving at least 24 hours between coats to allow for sufficient drying time. You may want to finish with a layer of wax once the paint is dry, as this will help protect your boat from damaging UV rays and debris.

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Tips for a smooth, long-lasting finish

A smooth, long-lasting finish is the ideal outcome you’re looking for. These handy tips will help you to achieve the best possible result.

• Choose a marine-grade paint that’s been specifically designed for boats
• Work in a dust-free environment, where possible to avoid debris getting caught in your primer and paint layers
• Painting is best done on a day that’s not too cold to ensure efficient drying
• Avoid painting in direct sunlight as your paint may dry too quickly, resulting in imperfections
• Ensure all dents and dings are filled and smoothed out before applying primer
• Opt for a range of sandpaper types to ensure you have what you need for each step
• Follow the instructions provided by the primer and paint manufacturers, especially when it comes to drying times and deciding how many coats are needed
• Apply a wax layer once the paint has fully dried for added protection
• Regularly clean and maintain your boat to keep its paintwork looking great

Related: The role of boat covers in preventing sun damage

Common mistakes to avoid when painting a GRP boat

As with all boat maintenance tasks, there are some common mistakes to avoid while repainting your GRP boat. These include:

• Rushing the sanding process and not creating an optimal surface
• Skipping priming can result in the topcoat not adhering properly, negatively impacting durability
• Choosing a paint that isn’t marine-grade or suitable for boats
• Adding primer or paint before the previous layer has had time to fully dry
• Applying thick coats of primer or paint rather than thin, even layers
• Painting during very hot or very cold weather can negatively impact drying time
• Working in a dusty environment where particles can get into the primer and paint
• Using low-quality brushes and rollers, which can disintegrate and leave unsightly marks

Specialist boat insurance through Craftinsure

Craftinsure arranges cover for a range of fibreglass boats, including motorboats, yachts, dinghies, and more. It includes up to £5m third-party cover and protects your boat against loss or damage from fire or theft. 

Get an instant online quote today.