Below the waterline: epoxying, fairing and antifouling

Ifirmly believe in applying an epoxy protection coat when overhauling a hull as it ensures it will remain in good condition for years to come, without the worry of osmosis blisters occurring. In this case, as most of the gelcoat had gone, there was no other option than to apply the normal three coats to the bottom to give the necessary level of protection, but also to take two coats up to deck level as a base coat for the topside paints.

Note: In case you’re wondering why the photos here show the boat suddenly sprouting a cabin, in between the preparation stage described on the previous pages and this epoxying stage, Peter and I designed, laminated and constructed the boat’s new superstructure and foredeck.

It was a challenging task – it’ll be described in a future issue – but shows tangible progress towards a finished boat.

9 The waterline is carefully masked before the first coat of antifouling is applied, again ensuring a good thickness is achieved without runs.

4 With the first coat worked into every nook and cranny the next task was to fill and fair the worst of the imperfections. To apply filler we use wide, flexible Artex applicators from the local builder’s merchant.

6 The filler is placed onto the applicator and then drawn across the area to be filled in the same way as when using a normal filler knife. This spreader fills large imperfections quickly and smoothly, needing little sanding when cured.

10 Finally, and arguably the best part of the job! The masking tape is removed to reveal a sharp edge to the antifouling and signalling the end of this part of the project.

5 We mixed Jotun lightweight epoxy filler base and hardener 50/50 in appropriate quantities to suit the area being filled.

7 With filler cured the next coat of epoxy can be applied. Filling and fairing can then be repeated if necessary before applying the final epoxy coat.

8 As we were treating the entire hull with epoxy we had to re-mark the waterline again using the string-line and straight-edge method described last month.

3 Beginning at the bow it’s important to ensure the coating goes on thickly and evenly: it shouldn’t be rolled out too much but should avoid runs.

2 The mix was decanted into a roller tray and a synthetic short pile roller immune to epoxies was thoroughly wetted.

1 The epoxy was stirred well so solids in the base paint were properly mixed. Curing agent was then added and thoroughly stirred in.