Gelcoat Repair

I

imeche

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I need some advice please.

During the storms a few weeks ago my AWB sustained some damage to her hull, basically she slammed into the jetty finger and now has a scar approximately 200mm long by about 3mm deep. The fibreglass strands are showing.
I’ve covered the scar with tape in an attempt to keep most of the weather out.

We are lifting Knotty Lady out within the next few weeks and she will be on her cradle, hard standing in the open. I intend to attempt a repair myself (if all goes belly up, I will call in the professionals) but have no experience in this kind of D.I.Y. I suppose that I will have to clean the scar and surrounding area, fill it with gelcoat repair and sand/polish it to match the existing hull. It’s the sanding that really concerns me. I can’t see how I will be able to sand any filler without scratching the gelcoat surrounding it.

Any advice is greatly appreciated.
 
If you fill with gelcoat you can get the repair pretty level (use a flat edge to smooth it over once enough filler is in - a bit like Polyfiller on your walls at home!)

Then use wet and dry sandpaper - but a REALLY fine grade - on my racing dinghies I used P2000 (available from Halfords or other car body repair suppliers). This will get the area smooth - the trick is to use a sanding block and keep going until the outline of the repaired area disappears. Then use a cutting paste to rub the area over (this is a very fine version of sandpaper).
Clean the area off and then use a polish to bring the shine back - I use the T-Cut colour restorer and lots of elbow grease!!

Its quite hard to get a pro looking finish - but the key I've found is to keep going. If it still looks dull and matted after polishing, give it another polish, and another - maybe even using an electric buffer and car polish to bring the final shine back.

Hope this helps

Jonny
 
There are very few jobs on the boat that I will not tackle myself. However a good gelcoat repair is almost impossible without 200 years of experience. I'd be inclined to ask around to find who is recommended, then get a quote. Far less frustrating.
 
DIY means that it will always be visible. You wont get a perfect gelcoat colour match.

If you want the hull to look as it was get a professional in.

Donald
 
Yes - I did assume you had gelcoat to match. The builders can often supply this. However, you need to be aware (especially on yachts as they are left outside all year) that your gelcoat will have faded and hence a perfect match is near impossible (it works ok on racing dinghies as they tend to be stored indoors or with hull covers).

You can get diy gelcoat kits and try to match yourself - these won't get you a perfect match and you'll spend hours trying!

Jonny
 
Agree with most of the other comments. The colour match is almost impossible. Before starting work wipe the area with acetone. This will show up any 'invisible' cracks that will need to be ground out. A dremel or similar with the sanding wheel is very good for this. Like pollyfilla gelcoat always seem to shrink so you will fill and sand a few times.
 
when I had a £25 mini van (tells you a bit!)I did the body repairs myself ....now I have a decent car, I'd take it to a body shop. I take the same view on boats really....repair the tender ,get a man who knows on the big boat!
 
G'day cam,

If you clean the repair area with Acetone and let it dry out then, "Dry Sand" with a 350 to 400 grit, collecting the dust as you go, you can mix this with the final (Top) layer of gelcoat to get a closer colour match.

The above method is used by many of the 'pros' as the pigment added is not only the correct colour but also the same age, this means that fading will continue at a closer rate that with a perfect match in new material.

I have yet to see the gelcoat repair that was not visible a few years on, the fade rate of the original and new material are not the same.

Avagoodweeknd......
 
think you ll need about 18 degrees to get the gel to go off.
Id be a bit wary of using anything under 800 grit as getting those rougher sandpaper swirls out is a nightmare. 800-1200 and soapy water. You can get a reasonable match yourself, but its a couple of hours unless you re an artist anyway. Try black/red and yellow pigments, but you need a pin drop in100ml of cream coloured gel, and alot of attempts. Quite statisfying on a warm day.Wouldnt care for it this time of year.Note it tends to change shade a tad when dry. CLS or CFS in redruth do the stuff in man size quantities. i reckon £30-50 quid will get you all the mixers.gel,pigment gloves etc etc you ll need, but, seriously, it will be a cold miserable job at this time of year, and I m not even sure it will set.
 
Am I wrong here or is everyone else missing the point?
You have a scar 200mm longx3mm deep with fibre strands sticking out?
If I were you I would forget filling out with gel-coat and get an experienced person to look at it for you, as it sounds very possible that you could have a fracture there which I for one wouldent be repairing with gel-coat alone.
Sorry to sound so pesimistic but do at least have a good look at the inside of the hull in that area checking that the grp is not crached right through.
 
Thanks to all. I had decided to get the experts in and then Clyde's warning put the tin lid on it. I believe that there is a guy at Port Edgar who is well thought of.
 
On a slightly different tack, if your boat's repairs develop a different colour what can you do about it? I was looking at a 28 footer the other day with such a problem and was wondering how much it'd cost to put it right. though the broker assured us "nah, its common for boats to have discoloured patchwork"
 
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