Repairing small ding in the gel coat?

[Wardy]

I've got a small scrape in the gel coat on my westerly konsort, on the transom,my fault entirely (slight mooring problem). It';s about 2" x 1" and an eigth" deep.
What is the best way of repairing this and trying to get a decent colour match?
please give me as much detail as to the process as i havn't got a clue but i am reasonably able to be able to do the work myself given the info!

TIA

Steve

 

[john_morris_uk]

The colour match is the problem, the repair itself is fairly straightforward and easy.

In theory you find some gellcoat (white) and you mix in some gellcoat (various colours) to make a perfect match. A local GRP specialist here in the West Country talked to me about Westerly's having a lot of green in their white. I am not an expert on colour (ask my SWMBO as she is an artist and finds it very funny that I can't see the blue in that tone of colour on some flower or something - to me its just a red flower)

As far as the repair is concerned, the easiest way is to use a gell repair kit. If you buy ordinary gell coat and hardener (the two must be mixed at the correct ratio), the gell also needs to have the air excluded from it to go off properly. People use a laminate film or plastic sheet over the repair to do this. If you use a gell repair kit, you will find they have put an additional chemical in the gell mix that means it hardens properly in the open. Follow the instructions in the kit for correct mixing. The kits are fairly cheap and I did see one advertised once which had a few different colours in it.

In practical terms, you need to grind the scratch out (a dremel is very good for this I am told - however I use a grinder) and ensure that there is no damage to the underlying glass layers which would need repairiing first (unlikely from the sound of your scratch). Make a shallow 'V' of the whole damage. You then fill the whole site 'proud' with gell repair and wait for it to harden. Then using lots of water as a lubricant, you sand the 'proud' gell repair back. If the area is flat, you MUST use a sanding block. I have two - one is cork and fairly hard, and the other is a rubber one which conforms to minor curves. Start with coarse (120 grit, if its really proud, but work quickly to 240 and at least 1000 grit) If you find there are any voids, just fill again and carry on. With a bit of patience and a good colour match, the repair will dissapear before your eyes. Finally, use a rubbing compound and some wax finish to bring the shine up.

Hope that this is simple enough. There was an article in PBO a while ago which gave a blow by blow account with pictures, so if you really wanted you could pay for a copy of the article.

No doubt someone will remind me of the chemical that is added to gellcoat to make it go off in air - can't remember this morning...

 

[alan]

Suggest you have a look at a West marine publication on repairing fibreglass and gelcoat. Most of the info is in there; I think their books cost a tenner.

Alan.

 

[ShipsWoofy]

GRP repair manual

 

[Hardley]

Yesterday I repaired about 20 small holes & scratches on my ageing boat.
Colour match is just about impossible to achieve, without hours of fiddling, even then there is no guarantee that you will get it perfect, be content with a near match.
I call the chemical to mix with gel-coat, so that it will go off in air,"gel-coat Polish", thats what I ask for when I go to the guy who makes kiddy's toys near me, his price is usually a couple of quid. Mix it in first at the same ratio has the hardener.
Grind scratch out to a V. Blow dust away or suck up. Cover surrounding area with masking tape, right up to scratch, roll edge of tape back 1/8 inch. Wipe scratch with asatone. Allow to dry. add hardener to Gel-coat/polish, mix well, 2-3 Min's.
Apply gel-coat to scratch, just proud, too much and you have a lot off sanding back to do. If gel-coat tends to run out of scratch, cover with sellotape, pushing gel coat back into scratch.
Test as it goes off, when it feels rubbery, take masking tape off, if you have over filled now is the time to cut off the excess, but still leave proud until completely hardened, then use wet and dry paper to finish off. I start with 300-400-500-600- and finish with 1200 grade, then a fine grade rubbing down compound and wax polish.

 

[gjgm]

think you have plenty of info already, but a search on here and mobochat will give you plent more threads.
If its an off-white gel, you can get a pretty good match. Fiddly? maybe, or relaxing depending on your temperament! I m not going to repeat it all here, so pls do a search. Advantage is when you get it right you should have enough to store for all other mishaps.
But the simplest way is a gelcoat repair kit in a tube by plastic padding for about £7. Its quite a bright white, and they dont recommend any pigments, so its a question of how bothered you are, or how evident the location is. Take you ten minutes. Its good to have a tube as it will make a quick repair, and you can always revisit the repair at a later date, sand it out, and play about with pigments and gelcoats when you have more time. Worth noting, that for gelcoat, you really need at least 16 degrees plus, and prefereably 20, which means early season is a bit cool. But if there is one message, is that as long as there is no damage to the fibreglass underneath, a 10 year old can do it !( if the repair cracks, then its probable the fibreglass underneath is damaged and is flexing; possible if you gave the boat a big bash)

 

[BrendanS]

There is a great thread click here which goes into great detail on gelcoat repairs, and all sorts of tips and tricks

 

[Wardy]

thanks for all the replies and information, i'll get to work this weekend if the weather is warm enough.

cheers

Steve

 

[Lakesailor]

" If the area is flat, you MUST use a sanding block."

This can't be over-emphasised. If you use your fingers you willl get depressions in the good gel-coat around the repair.