Fibreglassing

So…..where were we?? Before the launch, the last thing I wrote about was laminating Kensa’s stem. Clearly a lot more happened with the boat build between then and the 19th August, not least turning her over, putting some paint on and drinking epic amounts of coffee. In my head, I was going to update the whole blog a long, long time ago, so that everyone could read about the rest of our time building Kensa while her launch and the last few coats of paints were still fresh and tacky in our minds.  However, blatantly that didn’t happen. BUT, be excited my friends, be very excited, because it is happening now and this is just the first in a flurry of new posts giving you exclusive detail on the remaining items what we stuck on our boat and painted. And right here, right now, is what happened when we started fibreglassing……..

Here is what I knew about fibreglass before we started building our boat: somehow it is something that ends up looking like shiny hard plastic and yet starts off looking like fabric. A process happens between these two stages; I believe it is called ‘lamination’ but it sounds quite boring and complicated and I would prefer (as with many other scientific phenomena like electricity and internal combustion) to think of it as ‘magic’. My husband talks about it a lot and uses words like ‘chop strand mat’ and ‘polymers’, which I regard as watchwords for nodding and mumbling appreciatively while continuing to watch Hollyoaks. To be fair, Si does the same when I start talking about etymology or syntax and I can scarcely blame him.

We were so pleased to have finally finished planking and to be starting work with new materials, but despite having done quite a bit of work with fibreglass in the past, Si had never worked with the same combination of cloth and resin we were going to be using, so he decided to talk it over with Alex Whatley, a friend and ex-colleague of Si’s from Falmouth Marine School. Alex works with the college to manage the Marine Innovation Service, a Cornwall College initiative supported by the European Regional Development Fund which offers specialist support and consultancy to small to medium sized marine businesses in Cornwall. Alex and Simon decided that it would be interesting and possibly beneficial to our build project to try vacuum bagging the fibreglass on a section of our boat, in order to ascertain whether this approach would be more effective than the alternative; traditional wet laying of cloth panels and resin.

This is essentially how fibreglassing works. First you need cloth made up of glass fibres. This comes in many different guises, and you make a choice depending on the strength of material you need, the type of resin you are using and the shape of boat you are working with. Oh and budget. Because like most bespoke tailoring, it doesn’t come cheap. The next step is to coat the fibreglass with resin. It is possible to use either epoxy or polyester resins in combination with glass fibre cloth to make fibreglass. We chose to use epoxy. Epoxy is a tougher, more adhesive, virtually odourless alternative to polyester which matches and exceeds all polyester’s properties of strength and impermeability. It’s a system of resin and hardener which when combined with each other react and form a solid plastic. This reaction is called ‘exotherming’. Previously I just thought this was a lolz way of referring to that feeling you get on your face when you’ve fallen asleep under a midday Mediterranean sun for too long, but there you go. We were using a biaxial glass cloth, which is stitched rather than woven and, as its name suggests, has fibres running in diagonally opposite directions to each other. We chose this cloth because it drapes well to fit the curves of our boat, plus it provides diagonal stiffness to the hull to stop it from twisting under strain. In addition, the fibreglass obviously seals and waterproofs the planks to give a strong but light, seaworthy hull. To build up the strength we needed, we used two layers of 450g/sqm biaxial cloth and epoxy resin.

We decided to vacuum bag the transom. As we were going to add a wooden outer transom towards the end of the build, it was worth experimenting with this section of the boat; if the finish was not as fair as we’d hoped, nobody was going to see! Vacuum bagging requires a few more materials and tools than hand laying, as well as space and expertise, so we were delighted that the Marine Innovation Service was able to offer us not only the loan of their vacuum pump and bagging materials, but also Alex’s help and hands-on knowledge for a few days. Vacuum bagging basically applies fibreglass by using atmospheric pressure to squash the laminate down and hold it one place until cured. Essentially it acts like a giant clamp, which allows you to apply several layers of glass at one time while removing some of the work of consolidation (squeegeeing out of resin). In addition to applying glass cloth and resin, we built up our sandwich of materials further with a layer of peel ply (a woven cloth that wicks up excess resin), a layer of perforated plastic film called bread wrap (because it looks like that, duh) which allows resin to travel upwards and be absorbed by the final layer of breather fabric (fleecy duvet). On top of all this we made one massive plastic bag out of plastic sheet fabric and sealant tape. The vacuum pump hose then attaches to a small hole in this and sucks all the air out. Genius!

The process worked well but we quickly discovered that the shape and construction of the boat meant it was hard to seal up all possible leaks in the outer bag and achieve a good vacuum. This, combined with a certain lack of space in the workshop and our own limited experience of working with the vacuuming equipment meant we felt we would be best off going for a more traditional approach of wet laying one layer of fibreglass at a time by hand and using peel ply between each layer to achieve a good surface to bond the second and final layer to. We are very grateful to Alex and the Marine Innovation Service for their support with equipment and time. Being able to discuss our options with Alex and benefit from his expertise to try out a different option was fantastic and we learned a lot from it.

And so we started fibreglassing the rest of the boat by hand. This is the (slightly implausible and very sticky) scenario. It’s a lot like sticking a large poster to a wall with wallpaper paste and a brush.Work out which area of the boat you’re going to put the first panel of cloth onto. Pour an enormous amount of epoxy resin into a roller tray. You need enough to cover the same area as the bit that’s going to be covered by the panel of cloth; this in turn is defined by the width of the roll of cloth and the shape of the area of hull you’re working on. Then you add the hardener to the resin. We’d been working with epoxy quite a bit up to this point, but never with such large quantities. And the thing about epoxy is that when you put lots of it in one space together all the molecules get all overexcited and jump around and have a party. It’s a molecular moshpit, a rave in a roller tray and you’ve got to get this sticky, expensive ticking time bomb of a liquid onto the boat you’ve spent months lovingly building before it goes everlastingly solid. Not only do you have to roll the resin out onto the boat, however, you also have to lay the cloth on it in the right place, roll more resin out over the cloth and squeegee the surface so that there are no dry patches, no excess resin or drips and no bubbles or wrinkles anywhere. All of this before the exothermic reaction kicks in and the materials bond together til the end of time. In normal ambient room temperature with the materials we were using you’re looking at around forty minutes. It’s like a profanity packed episode of the Crystal Maze without the whistles and portcullises.

Obviously the first time you do this you have to run the gamut of beginners’ mistakes; too much resin, not enough resin, laying the cloth in the wrong place so that you have to peel it off and redo it, by which time the countdown clock to epoxy zero-workability hour has run down a little further. But eventually you get there, and the feeling of stopping, taking gloves off and looking at a finished panel of fibreglass with the satisfaction of knowing it’s never going to need doing again is immeasurable. Inevitably the process leaves you a bit sweaty and entirely covered in epoxy. It also renders you incapable of taking any photos, which is why there are no pictures of us laying cloth or squeegeeing resin. 

The playlist is crucial, we discovered. Reggae is too relaxed, too slow; the otherwise perennial Paolo Nutini too devil may care; Muse too mutinous and angry. So we chose what goes best with an adrenalin and caffeine fuelled exercise: 90s electronica – and we Leftielded and Prodigied our way through the first layer of fibreglass.

Over the next few days things improved dramatically as with each panel we got more skilled at what we were doing. Coming into the workshop the day after putting the first panels on to find that the resin had cured and that the fibreglass looked suitably smooth and fair and fibreglass-like was reassuring and gave us confidence that we weren’t in fact ruining a perfectly sound wooden hull by covering it with shoddy lamination.

Another gladdening influence was sugar. As in many other areas of life, where fibreglassing’s concerned Haribo helps. Half way through our second bag of the day and about two panels into the second and final layer of glass some visitors arrived at our workshop. Begloved, dishevelled and munching on sour cherries, I waved at them as they came into the workshop and mumbled “Sorry, I’ve got a mouthful of Tangfastics.” Two of them looked vaguely familiar, but being unable to remember the name of these blokes I had presumably met in the pub at some point, I just smiled and chatted as we showed them round the workshop. It wasn’t until they left that we realised who they were. It turns out that I inadvertently introduced our fresh, local artisanal fishing business to two of the judges from The Great British Menu while chewing on global branded gelatinous confectionery. Oops.

So, at the end of this what did I learn? Fibreglassing; amazing concept, genius results, deliciously finite. We’re really pleased with the finish we achieved and delighted to have learned so much, but in all honesty? I wouldn’t choose to do it again.

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2 thoughts on “Fibreglassing

  1. Karl says:

    I have been gelcoating this week and will be thinking of you guys as I apply the second coat in the coming days. Well done.

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