Monday, 22 August 2011

Introducing Chemical Dependance to an Already Strained Relationship:

The boat before me was not the one I'd loved before. From the end of its glossy white exterior, the grafts sprouted as a bulbous mutation; their appearance not altogether unattractive, but alien, and altogether incongruent with everything that made that vessel what it was. Their host was not intrinsically different however - in construction and shape they couldn't be more closely related. Yet all that connected them were two dozen zinc-plated screws. What, I asked, could resolve these tensions and unite the two forever?

Answer: Thermoplastic and woven glass extrusions. Duh.

Here's how we were situated, with a hull extension like the one pictured (left) on each side of the boat. These were not strong enough to cope with any of the forces they were designed for, as all that was holding them together (and on to the hull) was a few screws. Plus there were significant gaps on some joins, and the likelihood of any aspect of them being functional was fairly slim. Luckily, this was considered in the design process, and there was always going to be another step before their boat ramp baptisation - fibreglassing!

In case you were wondering, I mean with epoxy resin and woven boat cloth. As far as I'm concerned that is the only kind of fibreglass. Polyester resin and chopped strand mat existed only so that we'd all have time to practice and hone our skills before the real deal came along. I did not use polyester resin for glassing this boat for the same reason that I did not use Lego to make the engine mounts; both may be "easier to work with" but I would quite like a functional boat at the end of this. Ok!

Hull planed flat with extension, this was done on every contiguous surface
The first step was to plane across where the extensions met the hull, which provides a good surface for the resin to adhere to, and ensures that extension and hull meet at exactly the same level. The latter is crucial for performance and the former is crucial for strength, and with the electric plane it didn't take long.

Well, its now the part of the story where I talk about actual fibreglassing. If you have yet to try fibreglassing the bottom of something, I'm afraid I can't express the misery involved in normal prose, and suggest you imagine yourself trying to escape from a disused well that local residents use to dispose of surplus marmalade and net curtains. Hamish and I did the 'wet lay-up' method, where you brush on resin first, then try and push the cloth up onto it. It was tricky and we ended up with a couple of creases and bubbles on the first side, which appear opaque and white, whereas properly wetted out resin is transparent. These can be sliced or sanded off and then filled, so all was not lost.

The other side went much better, though I'm not sure why. We then glassed strips over all the joins that weren't already coated, then did another coat of resin over the rest. Wherever glass cloth wasn't hard up against ply there were more opaque spots, and these seem much more prone to having pinholes with no resin, so much care was taken in the resin coat to fill these little squares and ensure waterproofness. And that was that, woo!

And thats how two became one, and no stress (hydrostatic or hydrodynamic) would ever turn them apart (probably, don't want to jinx it!). I haven't taken any photos post-fibreglass, but here's what the extensions look like, see ya next time!

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