Copper-bottoming

We've had another productive but exhausting week at the boatyard in Totnes. The stanchions and guardrails are back in situ, which makes working on deck much less risky (the ramifications of a fall from height were too awful to ignore, so this was a priority) and the refitting of deck kit has continued. The big job, however, was to apply the Coppercoat antifoul system.

A yacht (not Maunie) suffering heavy fouling

For those not entirely au fait with the life cycle of the barnacle, boat hulls are perfect targets for the little blighters to set up home. If allowed to do so, they quickly encrust the underwater surfaces and, together with any weedy fouling, cause huge amounts of additional drag as you sail. Wooden vessels can also be afflicted by the teredo worm, particularly in warm waters, which bore into the planking with potentially disastrous consequences, so the battle against underwater invaders has been fought by sailors for centuries. Back in 1761 the Royal Navy first began applying sheets of copper to the bottom of their ships - it turned out to be an expensive but worthwhile process (hence the phrase 'copper-bottomed investment') as the copper repelled barnacles and also prevented the teredo worm from being able to bore into the timber.

Today, most yachts use an ablative antifouling paint, applied annually or (if you're lucky) bi-annually. Containing a cocktail of fairly unpleasant chemicals, the painted surface is soft so it slowly erodes, preventing barnacles and weed from gaining a grip on the hull. The annual cleaning and repainting process is the yachtsman's least-favourite task and, with the cost of a haul-out added to the cost of the paint, it's an expensive process. Also a key driver for our move from antifouling paint to Coppercoat was reducing the environmental impact.

Back in 2011 we had Maunie's hull slurry-blasted back to clean fibreglass, five coats of epoxy sealer paint were applied and then Coppercoat added. As its name suggests, Coppercoat is the modern equivalent of nailing sheets of copper to the hull; very fine copper powder is mixed into an epoxy base which is then applied by roller. The resulting finish is hard and provides effective anti-fouling for up to 10 years with nothing more than a regular scrub to keep the hull clean. After 8 years and thousands of miles, however, the coating on Maunie's hull was wearing thin so we knew it was time to apply a fresh coat. The yard quote for labour to do the job was close to £2,300 so we decided to do it ourselves; the manufacturers provided excellent instruction and videos so we braced ourselves for two and a half days of hard graft:

The first job was to sand back the old Coppercoat - a vacuum cleaner extracted the dust but a face mask is a vital extra as epoxy dust is pretty nasty

The sanding reveals the copper colour

The epoxy base is a two-part mix...

… and a drill-mounted mixer made it easy

The very fine copper powder is mixed into the epoxy - about 2.2 kg of copper per litre

Di at work. We applied an epoxy-only coat onto the hull first then five coats of Coppercoat, each applied when the previous coat was still tacky. You can see the white patches on the keel where the original Copper coat had worn thin

The trick is to apply very thin coats, so the first coat looked fairly patchy

After the third coat things were looking better. 

With just two people the process is hard work. Once mixed, the product has a pot life of only about 30 minutes so we had to work fast to get it all applied in time. One litre of mix was enough for a single coat of one side of the hull and we'd decided, wisely, to do one side of the hull at a time. Once we'd finished the coat, we had about 20 minutes of rest before starting the next mix.

Motivational donuts and coffee between coats

The end of day one, the hull half completed

End of day 2

The epoxy is water-based so didn't give off horrible fumes but it needs good air flow to allow it to dry. When we started the port side we found that there wasn't any breeze in the shed and the coating was taking an age to harden; luckily we were able to borrow a huge industrial fan which solved the problem in a few minutes.

While we were working, Andy the painter came to polish out a couple of minor imperfections in the paint. He has done a brilliant job.

The best bit of the job - removing the masking tape

Done! Well, not quite - after five days to let the surface harden, we need to move the supporting pads to coat the four patches of old surface that they will leave.

Maunie emerges gleaming - and our work begins again

On Wednesday afternoon a very shiny Maunie emerged from the paint shop and into the light. We are absolutely bowled over by the Awlgrip paint finish; Andy the painter is really an artist with a spray gun and she looks like new. Gone are the scratches, abrasions and other imperfections of 30,000 miles of voyaging, replaced by a completely smooth surface and a really deep shine. These photos don't really do it justice...

We now moved back into the big shed to take over the next bit of the project - putting her back together again over the next couple of weeks. As you can see from the last photo, there are some important bits to replace onto her stern but the really big challenge that we face is to refit all the deck fittings. The new deck is all but complete, with just some minor finishing work to take place next week, so we used the templates that we'd carefully made to identify the position of all the bolt holes, took a deep breath and fired up the drill!

The first task was to drill the holes for the feet of the pulpit...

… followed by the cleats and other foredeck fittings. Note the vital kneeling pad!

We used a good tip we'd been told about and drilled all the bolt holes 1mm smaller than the thread size; that way we were able to cut a thread through the polymer deck material which adds a further level of protection from water ingress. Of course, we added Sikaflex sealant / adhesive to complete the waterproofing so Di spent a happy couple of hours carefully applying masking tape around each fitting to prevent the black sealant from spoiling the look of the decks.

Blue gloves on for the Sikaflex - a ring around each bolt hole, followed by additional lines to bed down the fitting onto the deck. The felt pen marks on the fibreglass were used to locate the templates that we used to locate the drill holes.

Screwing in the bolts. Though we re-used the old fittings, the new stainless steel bolts have Allen-key socket heads which look neater and are much easier to undo than the old slot heads (should we ever need to remove them, which we hope we won't!)

The modified stanchion bases that Graham designed look great but have been a bit of a challenge to fit. Getting the bolt holes to line up has been an interesting challenge but we now have 6 out of 14 in place, sealed and bolted. We think they should work really well.

The first base in place and masked up, ready for sealant. You can see the grain effect of the Tek Dek and the very neat, no-caulking fit against the fibreglass of the bulwark.

After two and a half days of very hard work, we were glad to be heading home for the weekend (especially as it absolutely tanked it down with rain all day today). When we next go back to Maunie we will continue with the deck work and also have the prospect of a full day (or more) of applying new Coppercoat antifouling. Living the dream, as they say!