Monday 21 April 2014

Osmosis!

I'd been hoping to tie the boat up amongst the mangroves somewhere for the hurricane season, and go back to the UK to work for the summer. But the appearance of blisters below the waterline persuaded me to have the boat lifted out in Antigua instead.

One of the last jobs I did on the boat before leaving the UK was to paint on 4-5 layers of epoxy paint to prevent osmosis, followed by £700's worth of Coppercoat antifoul. I had measured the moisture levels in the hulls with my moisture meter soon after the boat had come out of the water. It seemed fairly dry to me. Not as dry as I would have liked, but dry enough to risk leaving the gel coat intact. There were very few blisters anywhere. A bit of epoxy would be enough to prevent osmosis I figured.

That was wrong. It doesn't take much moisture for osmosis to start. And it seemed the epoxy wasn't much of a barrier coat - I used epoxy paint, but not paint especially formulated as a barrier coat. That, I appreciate now, is an important difference. I've heard also that osmosis often begins when a boat is first taken to the tropics.

Well, however it began, and whatever miscalculations I'd made, I figured the sooner I stripped it the better.




Read all the websites about stripping gel coat, and they all say it is definitely a job for the professionals. This wasn't an option for me, as there was only one gel coat peeling machine on the island, and the price the fellow gave me for the job was far too high. And he wouldn't let me hire the machine from him. So I imported another machine from the US, did the job, and sold the machine on to the boat-yard. That fellow's monopoly on gel coat stripping is bust!

The job really wasn't that hard! It was a bit difficult under the flares of the hull, but the rest was straight-forward. Under the gel coat is a layer of chopped strand mat, which isn't really structural so it's not that important that sometimes the machine removed a bit of that. Still, it was best to leave that in place as it provides a bit of leeway when it comes to sanding and faring in the hulls again. What made the job harder and quite unpleasant was working in the heat. Overalls were unbearably hot and quite impractical, though mask and eye protection and ear defenders were essential. The fiberglass dust soon coated sweaty skin until the itching became unbearable. Even a cold shower wouldn't stop the itching, but eventually I was informed that scrubbing myself with a scouring pad in the shower would relieve me, and so it did.

Removing the wooden beaching shoes. I'd glued them on with some mastic that bonds less strongly than the gel coat is bonded to fibreglass. Strong enough to keep the wood in place without any bolts, but easy enough to pry off with mallets and wedges without causing damage.


Antigua with the heat, sunshine and wind is a fine place for the fibreglass to dry out. As the boat dries, salt and soluble parts of the resin are brought to the surface, and this stuff needs rinsing off occasionally. I've arranged for the yard to rinse the boat once a fortnight for the first few weeks.

I hope to ship a pallet of glass, epoxy and all I need to finish the job over to Antigua. It will be cheaper buying the stuff here, and will save a lot of running around trying to source things. I plan to give it a couple of coats of epoxy, a layer of new biaxial glass, then fill and fair till I've had enough, a couple of coats of epoxy barrier paint, and then more Coppercoat.

The Coppercoat was good! It needed scrubbing every week or fortnight, which at first I thought was a bit much, but I saw other people having to scrub more often, and to the point where they'd scrubbed through their antifoul.

So, this blog will go even quieter than usual for the next few months, till the British summer and the Caribbean hurricane season is over.

A bit of fibreglassing, and then off to the leeward islands, and Cuba? Florida?

2 comments:

  1. Such dedicated bloggers. This is such a tough time of year. I am very glad read about this blog i am sharing great information with you. back cove 30
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  2. I see on Woods Eclipse plans he ONLY mentions epoxy ,no polyester resin,good news forfeiture used Woods Cat buyers eh!

    ReplyDelete