Tuesday, 20 January 2015

Laminating the hulls after drying them out.

Back in Antigua in December, I set about fixing the hulls, after they'd been sitting stripped of gel coat for 6 months. The yard had washed the hulls several times to remove the solutes. There is so much advice around about the treatment of osmosis, and much of it contradictory, I eventually settled on this interpretation of the problem, and did my best to implement the recommended solution.

There were some obvious problems with the laminate:

The pale area in the centre is an area where the original glass wasn't wetted out sufficiently. The whiteness is caused by air in the laminate. Fortunately, this was the only area I found like that.

And here is a badly implemented repair. The lighter area of laminate near the bottom of the hull was still sticky! So the resin had never gone off - I guess whoever did the repair forgot to add the catalyst.

These problem areas were relatively small and easy to repair. However, the both hulls showed cavities between the gel coat and the chopped strand mat:

Under all the blisters, this was apparent. The white areas are where the resin hasn't filled the glass properly. After sanding, those areas looked like this:

I'm convinced that these voids between the gel coat and the glass was the cause of the blistering. Water gathered in the voids, and osmotic pressure resulted in the blisters. I'm hoping elimination of the voids will fix the problem.

I sanded both hulls, removed any damaged glass or glass that hadn't been wetted out properly, and replaced it with glass and epoxy. I then sealed the hulls with a coat of epoxy, and spent many days filling and sanding to fill all those cavities. Apart from the unpleasantness of sanding glass fibre in tropical heat, there were mosquitoes, sand flies, and the noise from the islands generating station which is next to the yard to contend with. The weather was kind until I started laminating. I did a small area one day, and despite the difficulty of sticking on sheets of glass onto the bottom of a hull in the heat and the wind, I was pleased with the result. The following day was all blue sky - not a cloud in sight - so I set about laminating a bigger section. All went well till I'd nearly finished, and the sky went dark and the wind kicked up, and a terrific squall ruined all my work within 10 minutes. Not only was my work spoiled - I had to pull off all the glass I'd stuck on - but it meant I'd lost a lot of the specially slow hardening tropical epoxy I'd imported. Well, I had'nt lost it all. Quite a bit ended up on my skin. After clearing the mess from the boat, I went to the shower block, and doused myself in vinegar - the only safe way to remove epoxy from the skin. Boy, that caused those mosquito bites to sting. So, rubbed down with vinegar, I turned on the shower to find the water was off! I eventually found a stand-pipe in the yard that worked, and in desperation, abandoned modesty and washed the mess off.

I did no more laminating until I had the boat moved indoors. This was much better. No sun and no wind to complicate things, but the mosquitoes preferred the lack of wind and were pretty relentless, day and night.

One good aspect of having a catamaran is that it is easy to adjust and change the propping arrangements. The whole boat can be supported by just the beams, so the hulls can be worked on from end to end without supports getting in the way:

Note the kitchen waste has been connected to a hose, so that water from the sink doesn't dribble down the hull.

I worked 40 days non-stop to repair and re-laminate the hull. Sometimes my eyes would wander...

Somewhere, under the rainbow.

At last, the work was done.

Ready to go...

Splash, and within a couple of hours, we were anchored off Great Bird Island, and had the island to ourselves:

On to Barbuda:

And now in St Barts. Tomorrow, St Maarten...etc

No comments:

Post a Comment