knobbly gelcoat

[Guest]

Just bought a 1972 saiboat in need of attention. Some of the gelcoat on the coachroof is rough, raised and knobbly, presumably as a result of water entering through screw holes that weren't sealed properly. The total surface area is less than 10cm x 10cm

My question is whether I can simply sand it down until it's smooth, and then apply new gelcoat and polish, or whether I need to surgically remove the outer glassfiber, repair the core and apply new glassfiber, gelcoat etc.

I hope that as this doesn't appear to be a structurally vital area I can get by with the former.

Am I right or horribly wrong?

Thanks in advance for any advice

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[graham]

I had a similar repair to do on my boat. If water has soakes into the inner core then you have to cut away the grp outer skin remove all trhe soft wet core .Replace the core with replacement core if you can get it or marine ply the same thickness as the old core then glass it back over sand fill and paint.

To find out if water has got in try drilling out one of the old screw holes ,If a load of wet muck comes out you need to fix it at some point. If the swarf is dry then you will get away with drilling out all the holes filling with epoxy filler then sand and paint.

Personally I would fill the holes temporarily with silicon then do the repair during the winter lay up .

Best of luck with it Graham

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[warrior40]

What design/class is your boat?? Doesn't sound like incorrectly sealed screws to me. What colour is the original gel coat? My guess is that it may be a pale green or grey? Sometimes coloured gelcoats are not as good as white or clear ones, due to the properties of the pigments applied.In Yachts moulded in the 60's and 70's it is not unusual at all to have problems due to this. Deck mouldings are often imperfect from new, right from day one, as the non slip patterns are prone to creating airbubbles ( in the case if the small diamond patterns). The type where the non slip is just artex'd onto the mould is subject to the usual random pattern -good and bad -that you would have on your 1980's ceiling at home if you had done it yourself! Providing it is not in the area of the mast load taking area, there should be no problem in sanding, filling with fresh colour - matched gelcoat, then re-sanding and polishing. But, are you sure its that bad??

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[Guest]

Shipman 28 - swedish built. I'm pretty sure the water's come in via some badly sealed screw holes adjacent to the area in question. It's on the side of the coaming, where the aluminium bars for the sprayhood attach to the side of the boat. The gelcoat is white, and the non-slip is small diamond pattern. It's on the coaming

"But are you sure it's that bad?" Well, it's pretty ugly and unless the holes are sealed it'll probably spread, so it needs to be fixed doesn't it?

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