Preparing hulls for glassing

Even More Sanding

Posted by Paul

I spent nearly a whole day on the boat today and I also had some help from Lauren and we did the coving (some people call it filleting) on the outside hull at the chamfer panel (and a small amount of the inside hull coving) and removed all of the peel ply which also required some sanding as described in my last post. Lauren is looking to be a boat builder and hopes to get an apprenticeship but in the meantime helps me out from time to time and also attends TAFE on Mondays doing a course on composite materials. So if anyone reading is looking for an apprentice please email me.

The idea with coving is to create a gently curved fill on the chamfer join to lessen the abrupt angle that the fibreglass has to make in going from one panel to the other. A similar curve is required on the inside of all of the panel joins inside the hull and another similar cove will be needed on both sides of each bulkhead where they meet the hull panels, again so that the fibreglass doesn’t have to make right angle turns as the glass cannot stick to the inside corner of the join and if not coved also creates a stress point at the corner that weakens the glass and the strength of the join. My understanding is that the load is spread over the cove and out into the panels when a higher radius curve is employed. It makes sense.

I created a round ended filling spatula by tracing the shape of a plastic container onto a plastic scraper and cutting out the shape with a jigsaw, then using a sanding disc as a grinder in a drill, I rounded and shaped it further and made a chisel like edge on one side. I then used it to apply the filler to the join and then used its shape to remove the excess leaving the shape that I required in place and almost smoothly to each flat panel top and bottom so that only minimal sanding will be required to finish it.


I will still have some sanding to do when it is set just to feather it out to the flat panels to create a smooth surface with no ridges or scars for the fibreglass to bed down onto. I cleared away a lot of the dust on the hull with a wet towel to minimise dust in the air. So I am just about ready to glass the hull. It is a big job and I will almost certainly need help, and it will also help if the weather is a bit cooler. It is starting to cool a bit now, we may have seen the end of summer but it is still warm at around 28 each day and the heat hasn’t left the shed yet. Perhaps by next week when I think I will be ready to glass it may have cooled further. I hope so.

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