Repairing boat mirror with polyester

If the mirror in your boat is worn, damp or rotten, it is better to replace it. Fortunately, this is a job you can easily do yourself. We have written a handy step-by-step guide on how to do this. Contact us for more information!

Polyester or epoxy?

You can make the new mirror from either polyester or epoxy. We have written a separate how-to guide for making a mirror from epoxy.

Supplies

The quantities of supplies listed below depend on the size of your boat's mirror. If in doubt, please contact us for tailor-made advice.

You will need various raw materials and tools for this job. If you order the following items from us, they are often dispatched the same day so you can get started quickly!

Raw materials:

• Polyester resin (1300 grams/m²)
• MEKP polyester hardener 2% per kilo polyester or topcoat
• Fibreglass choppend strand mat 300gr/m² depending on the size of your new mirror
• Stewathix 125 grams
• G4 adhesion primer (RESION polyester primer) (200 grams per square meter)
• Topcoat in colour (approximately 300 grams per square meter)
• Marine plywood

Tools:

• Acetone
• Mixing cups
• Mixing spatulas
• De-aeration roller and corner roller
• Paint trays
• Disposable flat brushes
• Latex gloves
• Half mask respirator
• Fibre disc with matching adapter for your grinder

Step 1. Removing the old boat mirror

First remove the old mirror with a chisel and sand away the remains with a fibre disc.

Step 2. Making a mirror from marine plywood 

Once the back of the boat is completely bare and all remnants of the old mirror have been removed, you can make a new mirror from plywood. Cut the mirror so that it fits nicely in the place of the old mirror.

Step 3. Gluing on the new mirror

Apply G4 adhesion primer to the ends of the plywood with a brush. Once the G4 has dried, make an adhesive paste by mixing polyester resin with 2% MEKP hardener with Stewathix. Add enough scoops of Stewathix until it becomes a nice thick glue paste. Secure the plywood sheet in the boat with the glue paste on the ends. Also finish the edges with the glue paste by rounding the corners.

Step 4. Cladding the new mirror

After the glue has hardened properly and the plate is secure, you can now cover the wood with polyester and glass mat. Prime the wood first with G4 bonding primer and, as soon as it is dry, start cladding. Tear the glass mat into pieces and first wet the wood with prepared polyester resin. Stick the mats on and wet them with polyester resin. Make sure you thoroughly de-aerate each layer with the de-aerator roller for a good quality laminate.

Step 5. Finishing the new mirror

24 hours after curing the polyester, you can finish the mirror with polyester topcoat in colour, for example. Has the polyester been applied more than 48 hours ago? Then it is advisable to sand the polyester coarsely with 80-grit paper and then degrease with acetone.

Make about 300-400 grams of topcoat per square meter. Apply it with a fleece roller.

Step 6. Follow up

With the new transom on your polyester boat, you'll be good to go for years to come. Be sure to apply a hard antifouling or a self sharpening antifouling to the part below the waterline.