Before we start painting
Firstly, you'll need to wear the right clothing. Painting can be a messy job, so you'll need old clothes or a pair of overalls; rubber gloves; and a hat. We also recommend that you wear a pair of safety glasses, especially when working underneath the boat.

And don't paint while wearing a woolly sweater or hat - as the fibres will get into the paintwork.

You’ll also need a few basic tools, including a scraper for scraping off any loose paint; some wet or dry sandpaper and sanding blocks to give the bottom a light sanddown; a bucket of water for the wet or dry paper; and brushes or a roller for putting your new anti-fouling on. And don’t forget some masking tape to mask off the waterline.


Anodes are best removed before anti-fouling, but if this isn’t possible, they can easily be masked up with some aluminium cooking foil.

Boat inspection
After lifting and scrubbing or pressure-washing off, the hull should be closely examined for damage and fouling attachment.

Grass, weed, loose or flaky paint and small occasional blisters should be removed by scraping back to a sound substrate using a scraper – with the sharp corners rounded off to avoid unnecessary gouging of the hull surface. Barnacles and shell growth need more thorough treatment, as their cement contains a hormone which encourages young barnacle ‘spat’ to settle nearby. After carefully scraping off remove any remains with wet-sanding until they are no longer visible.

Large hull areas can be dealt with by slurry blasting. Chemical strippers should only be used if they are marine types that are 100% safe to use on glass fibre hulls.

                                      wash down 

Osmosis is a common problem on glass fibre boats. Widespread blistering, or large swellings in the gel coat are a more serious matter, and should be dealt by a professional.

Surface preparation
Surfaces to be painted must be clean, dry and free from oil or grease.

Bare surfaces must first be primed with a suitable priming scheme, filling between coats with an epoxy profiling filler to make good any undulations. Existing antifoulings don’t usually need any special preparation, but they can be lightly wet sanded to remove small lumps and ‘blebs’ in the paintwork.

Antifoulings must never be dry sanded or burnt off with hot air strippers, as even at the end of a season they will contain toxic chemicals. So wet sanding with fresh water is the only safe way. Apart from being safer, the lubricating action of the water means that the job won’t take as long as you might expect.

                        preparing the surface

Propellers can be cleaned with a power drill and wire brush to give a smooth polished finish. The copper in bronze propellers usually keeps most fouling atbay, but a couple of coats of Pellerclean or Seajet Triple Pack can be used in areas where heavy fouling is a problem.

Finally, wash everything down to remove dust.

Priming the underwater hull
On bare and filled areas, you’ll need to apply touch-ups of primer to ensure good adhesion of the following coats. For a high performance epoxy primer, use SEAJET Epoxy Primers. This is particularly recommended when all the existing paint is removed and full coats of the primer system are required. Seajet 117 Multipurpose Epoxy Primer is also designed to seal prepared gel coat on glassfibre boats and is ideal for using on metal keels.

However, for small areas of touch up, or if a single component primer is preferred, apply Seajet 011 Underwater Primer. Observe the correct over coating intervals between each coat - this information is on the tin. Use a brush for small areas or a roller for large areas. But will SEAJET antifouling be compatible with any antifouling that is already on your hull? In most cases it will be. However, there are certain Teflon based antifoulings, which need to be removed beforehand.

If you don’t know what antifouling was last used or if the condition of the antifoul is not ideal, the best solution is to apply a full sealer coat of Seajet 011 Underwater Primer on your boat. This will give good adhesion to the following coats.