Repair & maintenance: Re-Spraying over gel coat

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Re-Spraying over gel coat

Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=5100
Printed Date: 15 May 25 at 3:45pm
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com

Topic: Re-Spraying over gel coat

Posted By: timeintheboat
Subject: Re-Spraying over gel coat
Date Posted: 25 Jan 09 at 5:18pm

Major gelcoat refurbishment can be an expensive job because it is time consuming and getting a colour match can be really tricky.

What then are are the problems with agressively rubbing the gelcoat down, filling it with a neutral colour - gelcoat or some other filler - getting the surface right and then re-spraying with a good quality 2-pack or similar quality paint.

If enough gel coat is taken back - what is the difference with this approach and that taken on some of the more exotic carbon boats? - where a re-spray is taken as normal maintenance - run back the top coat, spray on another.

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Like some other things - sailing is more enjoyable when you do it with someone else

Replies:

Posted By: Paramedic
Date Posted: 26 Jan 09 at 7:33am

Nothing wrong with doing this at all. On an old boat that's faded but is otherwise in good condition it's probably the best solution.

You'd need to use a plastic primer first, but other than that there is no differance in maintenance between GRP, Carbon or any other substrate once painted.

The disadvantages are a slight increase in weight as you'll not take enough gel off to negate this without rubbing through, and that any damage will show a differant colour should you choose one.

Posted By: Rupert
Date Posted: 26 Jan 09 at 1:55pm

There is also the problem that when selling on buyers can be wary of a painted GRP boat, as it is generally only done when hiding damage.

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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686

Posted By: Paramedic
Date Posted: 27 Jan 09 at 9:03am

I agree but this depends on the age of the boat. Also this guy is talking about doing it properly, not the half baked mess put on with a bass broom that people usually associate with a painted GRP boat!

As long as it looks the part i don't see a problem. Also some GRP boats are painted as standard.

Posted By: timeintheboat
Date Posted: 27 Jan 09 at 9:47pm

Absolutely paramedic, we are talking deck here (smooth surface - Lark Parker 2 - not some of that knobbly lasr deck stuff) to keep the surface in good nick and we are talking about a spray that is as close as possible to the gel colour, but trying to do this at less cost than trying to take all the minor cracks out and get an exact gel match.

I am not talking about digging some paint out of the garage and slapping in on a laser hull - which only ever looks awful.

I understand the concerns about a "painted" GRP surface on the 2nd market and normally it would give me the willies - but I can't help feeling that getting some power tools to sand down the top layer of gel, fill in the cracks and gaps with good quality filler, prime with plastic primer (thanks for the tip) and then spray. If anything I would think there would be a net weight loss and it would look great and be sound.

Thinking about it, it would probably be better to give (i.e pay) to someone who has more a practical bent than I. Wood and varnish - OK, plastic and gel are a bit outside my comfort zone.

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Like some other things - sailing is more enjoyable when you do it with someone else

Posted By: NeilP
Date Posted: 28 Jan 09 at 1:06am

Bear in mind that in order to get a good finish you will have to grind out and fill ALL the blemishes/cracks and flat the whole lot back to a perfect surface. Start by grinding out every crack/bullseye/chip, fill them with 2-pot filler then flat the repairs back until you can just still feel them with your fingers. Then use a block or a board and, starting with 240 grit production paper, flat the entire surface to an even matt finish so you can't feel the repairs any more. Then move to 400 grit and flat it all again until all the 240 scratches are gone. A VERY thin guide coat of black aerosol helps here - no more than an even dusting. If you really want a perfect finish, repeat with 600 then 800. Wash it down thoroughly with fresh water only, then spirit wipe and tack-rag the whole thing. Mask it all up and spray your primer - 2 coats. Guide coat it again and flat with 400 to remove all the guide coat. Wash it, let it dry, spirit wipe and then spray in the spots where you went through the primer. Flat the whole lot with 800, wash dry, spirit wipe. Re-mask, tack-rag and then spray your top-coats. Once the paint is hard, flat with 1200, then 1500 then 2000, then use a polishing machine with a good cutting compound (NOT T-cut, it's rubbish) to get the shine. If you do all that thoroughly and pay attention to the tiniest blemish, you'll end up with a finish Nigel Potter would be proud of. Above all, take your time with the preparation!!

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No FD? No Comment!

Posted By: Stevie_GTI
Date Posted: 28 Jan 09 at 1:18am

neil is right, with a spraying job its all about the prep work. For it to look like a top quality job you will need to give the surface lots of attention. Who is doing the spraying of the final coats?

Posted By: Paramedic
Date Posted: 28 Jan 09 at 8:38am

Ford diamond white is about as close as you'll get i'd say. Quite a few Parkers are painted now.