flowcoat asa topside paint?

Ian_Edwards

Ian_Edwards

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I'm currently in Australia visiting family and helping repair a 50 year old Corsair sailing dinghy (about 16ft, 2/3 man heavyweight dinghy).

The transom was reinforced with an aluminium plate and the gudgeon and pintle fixed with pot rivets. Salt water had penetrated the assembly and the aluminium plate was all but corroded away. This meant drastic surgery to remove the Al plate. That's all done and the repair is probably stronger than the original.

I now need to "paint" the epoxy glass repair to match the rest of the transom. It's a relatively small area, about 1m wide and 300mm deep at the centre. I don't really want to buy a can of expensive polyurethane paint for such a small area, but I do have white flow flowcoat in the garage.

Is it a good idea to paint with flowcoat??
 
Perfectly possible. A few years ago I watched a couple completely re-gelcoat the topsides of a 38 ft yacht. Their trick was to get the glass layer as smooth and level as possible, then apply gelcoat with a roller. Flowcoat contains wax, which means that the hard coat needs to be abraded before any subsequent coats, whereas gelcoat can be built up without intermediate abrasion.
 
You say "epoxy glass repair".

On the Cruiser's Forum (US centric) there are quite a few 'marine professionals' who are adamant that it's not possible to have a long lasting repair where you cover an epoxy repair with polyester gelcoat (despite what is says to the contrary in the West Systems book).

Apparently, the coating usually fails within a year or two.

Personally, I don't know if that is correct or not but thought I'd just pass this info on for others to comment on.
 
Thanks for the replies, I didn't know that there was a problem with gelcoat over epoxy, however, for a 50 year old dinghy which is essentially well past it's use by date, I'm not too concerned. I'm just trying to get it serviceable (and safe) for a little social sailing in Port Hacking (south of Sydney).

I've just flow coated the repair for the first time, and found it difficult to get an even surface, I'm left with brush marks, even after laying it off in one direction. It wasn't helped by the air temperature being 27 deg at 08:00 this morning, which meant the flowcoat cured very quickly, even with the minimum amount of catalyst I dare add.
I'm now going to sand it flat to remove both the high points and the surface wax and try again.
Any advice on how to get a smooth surface, brush mark free in flowcoat?
 
Ian_Edwards said:
Thanks for the replies, I didn't know that there was a problem with gelcoat over epoxy, however, for a 50 year old dinghy which is essentially well past it's use by date, I'm not too concerned. I'm just trying to get it serviceable (and safe) for a little social sailing in Port Hacking (south of Sydney).

I've just flow coated the repair for the first time, and found it difficult to get an even surface, I'm left with brush marks, even after laying it off in one direction. It wasn't helped by the air temperature being 27 deg at 08:00 this morning, which meant the flowcoat cured very quickly, even with the minimum amount of catalyst I dare add.
I'm now going to sand it flat to remove both the high points and the surface wax and try again.
Any advice on how to get a smooth surface, brush mark free in flowcoat?
Click to expand...

You wont get it smooth by brushing, it will need sanding and polishing.
 
Ian_Edwards said:
It wasn't helped by the air temperature being 27 deg at 08:00 this morning, which meant the flowcoat cured very quickly, even with the minimum amount of catalyst I dare add.
Click to expand...

From what i was told having considered this job for the cockpit last year, 27 deg is a complete non starter for flowcoat, dries to quickly. 14-15 deg I was told would give me time for it to be workable. That may not be easily achieved in your current location, lucky you :)
 
I've given up on the idea of flowcoat, 36 deg C here this afternoon!
I'm using polyurethane paint.
Thanks for the advice, I'll post some pictures of the repair, it may be of interest to someone in the future.
 
My son in law (in Sydney) was given a 50 year old Corsair (16ft sailing dinghy). I've been working on it, on and off, since I first got here in mid December.
The first problem was 3 holes in the hull, causing the boat to leak, I ground those out and repaired them with Glass epoxy and repaired various other dents. I then refastened all the mast a boom fittings with monel pop rivets, the originals had been aluminium, and had been fitted without insulation between the Aluminium and the SS fittings. This made the boat seaworthy and safe, so we took it away for a weeks sailing in St Georges Basin over Christmas.
On the last day of the holiday we took it out for a blast in 15, gusting 20 knots of wind and when we got back to the beach both the pintles on the transom were loose and pulled out without much effort.



They had been fitted with pop rivets, so I ground out the GRP and found a black mess inside.



Drastic action was required, so I ground out a panel and found that the original aluminium backing plate had corroded away and the corrosion products had split the GRP and forced the transom to distort.



I ground everything out and cleaned out all the corrosion products and fitted a new acetal backing plate. I did this in 3 section, so I could glass in the top and bottom sections.



I used micro fibre loaded epoxy as a filler/glue and self tapping screws to hold things in place until the epoxy had cured. I then used a grinder to feather the edges and scuff the acetal sheet.



The skin was then rebuilt using epoxy glass, taking care to re-build the bottom of the transom where the GRP had been badly damaged.



The area was sanded and filled and sanded.



All I need to do now is paint it and refit the hardware.
 
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