Newbie Fibreglass Question

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adamlang

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Merry Christmas everyone,

Sorry for the long question, and maybe stupid question.

I've a couple of jobs planned over the winter, the first is fitting a raised rope clutch to the Genoa furling line, the second is repairing a small hole in the gelcoat at the bow, I think with a small bit of fibre needing to be filled.

I'm starting to get organised, watching a few videos and working out what I need to order.

I need to raise the rope clutch (let's say about 12 mm) off the deck. I am thinking of using two bits of 6mm ply, I'll bond these with thickened epoxy, but my question is would a couple of layers of unthickened epoxy be OK for waterproofing, or would a couple of layers of fibreglass and gelcoat be better, it's also quite close to the diesel filler so chemical resistance may also be a factor. Looking for a bit of a small starter project to get into fibreglass anyway, with a larger job on the horizon, hence interest in a bit of a starter kit.

Thinking of getting this polyester kit to add to bit of west system epoxy I have, and for the gel coat repair:
Premium Fibreglass Repair Kit GRP 2.5kg Includes Filler / Tissue / Gelcoat | eBay

Obviously I can't mix the epoxy and polyester, but can I used them in the same project I.e. epoxy for bonding the wood, and polyester for laminating with GRP?

Finally is the Steven's GRP filler suitable, it seems to be an automotive filler, will that be OK just above the waterline at the bow?

Many thanks,

Adam
 
The ply is good but I would suggest using bi-axial cloth and epoxy for final waterproofing and added strength. Car body filler is OK above the water-line as long as it is also sealed with epoxy primer prior to painting. Bear in mind that epoxy sticks well to polyester but not the other way round. West system do excellent tutorial books on the whole subject of epoxy and it's uses.
 
Ply is Ok for the spacer, if it's good quality dense ply which won't crush.
If available, I find a few layers of GRP sheet good for this sort of job. I've used bits other people have cut out from hulls when fitting windows, bits cut from scrap hulls etc.
If you use ply, sealing it with epoxy is a good move. Drill the bolt holes slightly oversize and seal them too.
Although polyester does not stick to epoxy as well as the other way around, if the epoxy is fully set and abraded with sandpaper, gelcoat will stick to it well enough as a srface finish. You'll need to add wax to it or use 'topcoat' which already has wax in.
Epoxy is generally not good in UV light, so you need to coat it with something. Unless you have gel which is an exact match for the deck, it might be easier just to paint the ply block.
A couple of layers of plastic chopping board could work well if done neatly. Depending on the exact plastic, a wood plane is often good for getting a smooth glossy edge...
some of these things are pastics which will creep or crush under high loads, probably OK for this job though?
 
Thanks all,

I'm fairly confident about using the plywood to raise the clutch, its marine ply from some off cuts on another job. Painting it seems easier than fiberglass so that's a good tip.

On the hull repair by the bow, I think I need to check whether the hull is already painted or if its just gelcoat as this will determine whether I can use epoxy filler or not - it seems the stronger option but the polyester based gel coat won't sick to it. Also been reading a bit (books by Don Casey) and watching some videos (including Boatworks Today) and it seems that making some filler from polyester resin and fibers might be better than the automotive filler - something to do with the automotive filler absorbing water I think. While above the waterline, its very close and so I might treat it as if was below the waterline.

Anyway probably need to wait for some warmer weather anyway.

Thanks again,

Adam
 
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