How to Polish a Yacht’s Gelcoat

Almost all hulls with a gelcoat layer become dull when the surface wears off. Once in a while you should restore the polished look. Simply renew the wax layer that protects the gelcoat of unpainted dinghies from chemicals and marine debris. In this article, I will give you some practical advice to this procedure.

Almost all smaller dinghies and boats made of GRP (glassfibre re-inforced plastic) are sealed with a layer called “gelcoat”. The gelcoat consists of another, softer resin that should protect and seal the hull – and the gelcoat itself is in turn protected by a layer of wax or varnish.

The gelcoat is important for the appearance of the boat, because it has a glossy shine if in good shape; beyond that, its protective function should not be underestimated. It makes life harder for marine organisms such as barnacles, algae or mussels and therefore, should be kept in good conditions. Depending on the local climate and the kind of sailing that you do, the wax layer or varnish will wear off after some time.

In order to restore the wax or varnish, you can choose between restorers that use varnish-like compounds to replace older wax layers and seal the gelcoat instantly; or you renew the polish in the conventional way. The differences are probably marginal; restorers tend to be more expensive than wax, but might safe a bit of time if they come with a good kit for cleaning and polishing in addition to the restorer itself. In any case, you should get a couple of things sorted before you start your polishing enterprise.

Stuff to prepare before you start

Get yourself a lot of space where you can place your boat and access it comfortably from all sides. Make sure that you work in a well-ventilated environment, since you might use solvents and chemicals that can cause drowsiness and are generally unhealthy. Get proper rubber-gloves and working clothes. Get some buckets, good lighting (maybe a headlamp) and cloths.

Make a checklist with all chemicals / solvents / restorers / detergents that you will use and make sure that they are in place and waiting. Finally, get an electric buffer with sufficient cable supply to safe you manual swirl-efforts. Buffers come with orbital or circular motion, whereby the orbital ones are generally preferable for polishing jobs.

Step 1/3: Clean the Hull properly

Use a detergent solution or bleach to clean the hull. Brush it thoroughly without damaging the surface and make sure to get rid of all marine deposits that are not supposed to be on the hull. Rinse the hull with sufficient amounts of clear water to remove the detergent.

Once the hull is dry, you should check if the hull is greasy. If necessary, you can use organic solvents such as acetone or methanol applied on some cloth to remove grease and oils. In case you do, mind the ventilation of your workshop.

Step 2/3: Restore the Wax Layer

There are vast varieties of commercial waxes available for boats and you should have a chat with experienced sailors from your local area. They normally best which wax works best for the climate and maritime conditions of where you sail. In any case, the waxing procedure includes the application of the wax normally with a piece of cloth.

Then you let the wax dry (which means that you let the solvent evaporate – once again, make sure that your workshop is well-ventilated) and allow it to fill tiny cracks and pores in the gelcoat. Finally, you polish the wax-layer to restore the whole beauty of your hull.

It’s pretty similar to shoe-shining, really. Make sure to follow the instructions of the particular brand of wax that you are using. The big alternative to wax is the instant restorer that I have mentioned above.

Step 3/3: Polish the Wax Layer and let the Boat Shine

Once the wax is dry (follow the instructions – typically you allow the wax a day to saturate the gelcoat and harden), you can polish the surface with some cloth. Ideally, you would use the electric buffer for that. Polish only until the surface starts to look nice and shiny again. Polishing aims to remove excess wax and to smoothen the surface – buffing for too long might remove too much of the protective wax layer.

Once the hull of your boat looks shiny again, you can take it back to the sea. How often you have to repeat this procedure depends on you local climate and sailing habits. Generally speaking, polishing a hull once a year should be fine for most temperate climates. The gelcoat itself should last for more than 20 years if treated properly.

Further Reading

Back to "boats"

General Maintenance: Hull

Stripping a Boat before Paining it

More on Polishing Gelcoats and Waxes

Wikipedia on the composition of Gelcoats