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cliveshep
Thailand
1324 Posts |
 Posted - 22 Nov 2015 : 08:23:35
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As the question has been asked before and my response has now been lost I thought I'd post this again.
Some will have differing views - you carry on your way, no problem.
Repair is simple albeit messy if you are a boat builder or even an amateur willing to learn. I've had Lloyds A1 on hulls repaired by me where most owners would have given up - glass-fibre boats are remarkably easy to repair if some simple rules are learnt.
Lesson one - many will tell you to use epoxy from the get-go - no, the hull was made from polyester resin styrene-cured and with a little preparation that will bond more than adequately for even the most stressed areas.
Lesson two - You can and should use epoxy filler on top of glass fibre repairs to fair-off below waterline as polyester fillers like P38 are not waterproof. However they are fine where not constantly wetted. Note - polyester will not bond successfully to epoxy, only the other way round. Don't add too much hardener to the mix and make sure the ambient temperature and the resin temperature is adequate - no lay-ups in cold weather unless there is a heated tent.
Lesson three - chopped strand matt (CSM) is great for lay-ups over gel coat in a mould, but can be difficult to wet in and fold round tight curves or angles and tend to pull away and create bubbles. Use a woven cloth, roving or similar and it will drape beautifully, wet-in easily and be a strong job.
Lesson four - now you know what to use the how to is pretty simple, well rough the area with a mini-grinder and a coarse flap-disc - wear a mask and goggles - and if you haven't got one buy one off e-bay for under £20 new. For splits and large holes/impact damage sand both sides down to a taper keeping the angle acute as you want to lap onto sound material at least 75mm. Get some acetate - parcel tape, the wide brown one, is perfect for this if the area is not too big - and tape over the outside of the repair, and if possible support that by wedging a peice of cardboard, hardboard, chest of drawers - anything to stop the first lay-up bulging out through any hole.
Lesson five - cut the cloth to cover the inside of the repair, allowing at least 3 layers, each progressively bigger to over-lap the previous. Drape the first layer over the repair dry, i.e no resin, you'll find that woven bi-directional cloth or roving will stay there on its own as the tiny fibres grip where you roughed up. Mix some resin, not too much as you want the first layers to "gel" before continuing. Wet the area and the cloth, brushing it in gently to avoid pushing it beyond a split of hole. You'll see it go translucent as it "wets" in. Do not keep slapping on resin because a "resin-rich" lay-up will be weak and brittle. Clean up and allow to gell off stiff.
Lesson six - now repeat with the other layers and fresh resin. As the first inside layer has now stiffened you can now removed the acetate tape etc and repeat with small, larger, largest layers outside. Allow to cure until the following day unless it is very hot or you have raised the ambient temperature by heating.
Lesson seven - once cured hard you can paint a resin coat over a repair that is fairly smooth if under the water line and leave it at that without sanding or further filling - fish won't care if it is less than perfect, but if on show then you can after cure sand it smooth, apply filler, and progressively sand and wet 'n dry the repair before painting it.
All of the above is a simple way to repair almost any damage and know that the repair will not delaminate or debond although the downside is it will need to be painted.
A one sided repair using a mould and gel-coat can be made but it is pot luck if the gel will colour match and the repair is inevitably made on one side only and is not as robust.
Finally living the dream!
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Edited by - cliveshep on 22 Nov 2015 08:28:44 |
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Glass fibre repairs
