Matching non-slip pattern when repairing gelcoat

[Stemar]

I spent Saturday jet-washing a friend's Dufour 385. Leaving aside the fact that she changed colour, there are now several dings in the gelcoat where the surface was damaged, and the jetwash blew out the loose bits. The foredeck looks as though there's been a team of foredeck gorillas bashing a spinnaker pole about, which is disappointing on a lightly cruiseed boat.

I'm no stranger to GRP, having had a series of cars afflicted with tinworm in my younger days, but that was all about getting it dead smooth. Rather than re-inventing the wheel, and probably making a poor job of it, does anyone have any tips for matching the non-slip pattern on the gelcoat? It's a kind of square cross-hatching.

Thanks

 

[maby]

I've never done it myself, but I have watched an expert do it - looked easy enough, but I guess a lot of that is down to experience!

He had a bag of latex powder - you should be able to source it on the web or I guess that the larger artists suppliers may be able to help. You mix it with water and it produces a thick paste which will set to a flexible rubber after a while. He chose an area of undamaged non-slip surface close to the damaged area and rather larger than the damage. He applied some sort of release agent to this area - I didn't ask him what it was, but I guess that a light oil would do the job - and laid a ring of something around it. The ring he used seemed to be fairly heavy and metal and perhaps a quarter of an inch high - I guess you could cut a ring off a cardboard tube, or even build something with plasticine - it just exists to contain the latex till it sets. He poured in liquid latex and waited the period recommended on the package till it has set, then removed the newly formed mould, cleaning off the release agent.

He then applied more release agent to the mould, prepared the damaged surface to receive new gel-coat, mixed up the gel-coat, filled in the damage and pressed the mould down onto it. He took care to line up the pattern in the mould with the surrounding undamaged non-slip pattern, pressed it down and waited for it to set - the result was amazing. I suspect that the hardest part is judging how much gel-coat to apply - too little and it will not fill out the damage and the mould, too much and it will squelch out everywhere and make a terrible mess. I didn't ask him how he decided that bit!

P.S. some notes on making moulds with liquid latex here: http://www.themodelmakersresource.co.uk/articles/article006.html - not boat repairs, but the principles may be useful.

 

[jwilson]

I spent Saturday jet-washing a friend's Dufour 385. Leaving aside the fact that she changed colour, there are now several dings in the gelcoat where the surface was damaged, and the jetwash blew out the loose bits. The foredeck looks as though there's been a team of foredeck gorillas bashing a spinnaker pole about, which is disappointing on a lightly cruiseed boat.
Thanks

You are not the first to knock holes in deck gelcoat with a jetwasher, despite people insisting they are the best way to clean a deck in another thread here at present - see http://www.ybw.com/forums/showthread.php?436627-Novice-Question-scrubbing-deck

It can be done, mould from sound bit, etc, but even a specialist GRP man at a well known "quality yacht builder" - no names no pack drill - made a fairly visible repair to bits of my probably similar crosshatch deck gelcoat that one of their younger workers damaged prising off a toerail with lots of brute force and stupidity before I spotted what they were doing and stopped them.

I won't let a jet wash on my deck, and certainly not anywhere near any teak.....

 

[DannyB]

Just off the top of my head, what's wrong with just a blob of gelcoat, let it set, then use a triangular file to recreate the little pyramids. OK I confess I've done it, but it may have been a square needle file I used. Biggest problem was matching the shade of white.

 

[STATUE]

Go into Hobbycraft, buy Gedeo Siligum Moulding Paste.

Mix, roll out, place over a sound deck pattern, press to ensure all details are transferred onto paste.

Lift off.

Place over the fresh gelcoat you have just put down, place a medium weight over the area - lift off after gelcoat curing time.

Siligum will release from gelcoat 'cos that's what it does and requires no special wax etc.

Good Luck.