Bleak mid-winter gel-coat repair

Seakindly

Seakindly

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Last out of the water so must go back in some-time in March. Sadly I have an 8" sq patch of gel-coat to repair where a fender rode-up whilst in a marina. Tsk. Colour matching is no problem as the hull has been painted but I'm worried re: the filler and coat 'going off' when the temps likely to be low. If I use a hairdryer for a while to start the reaction -will it continue or stop when I cease using the dryer? Any tips most welcome.
 
Good question, I have the same problem, interested to hear from the experts.
There does seem to be 2 phases, one where the mix goes off quite quickly and then a longer process where it goes from tacky to completly dry. Will yours be a one coat job or do you need to build up several layers?
I hope to do mine on Wednesday when 10 deg is forcast.
 
Where are you located, it's not cold everywhere. If your repair is in sunlight you can use the UV light as a natural accelerator, don't catalise above 3% as this will resolt in the resin exotherming and it will have the strenth of an aero bar.
Warm air will help .
 
It also helps if the resin and hardener are at room temperature say 20 degree C, so that the mix is warmer than the 10 degree air temperature (projected) when used
 
One of the things to be wary of in cold conditions is condensation on the substrate from your own breath. Make sure it is warmed sufficiently to avoid that happening.

15C is normally the recommended minimum temperature.

It is possible to increase the amount of catalyst (to 3%, maybe 4% absolute max) to speed up the reaction time, but Im not sure if that applies to gelcoat

You may find some useful info on http://www.cfsnet.co.uk/ but really you should check the data sheet for the material you intend using
 
G'day Seakindly,

<<<If I use a hairdryer for a while to start the reaction -will it continue or stop when I cease using the dryer? Any tips most welcome>>>

Yes you can use heat to set the repair: Start by sanding the area with a 40 grit because you need to get a good bond or your repair will fall out next it gets a tap.

The edges must be feathered to avoid cracking and provide a good bond, clean with Acetone and apply heat to ensure it has fully dried out before applying any resin.

Warm the repair area and resin before you start, mix your resin and add 2% catalyst by weight of volume, the difference is minimal, then apply a layer over the area to be repaired and mix the into the remaining resin.

'Q' Cells, Micro balloons or talcum powder will work as a filler above the waterline.

Use a plastic ruler or other flexible material to fill the void to the required level keeping it at about 20 degrees and both ends hard on the hull so it follows the curve.

The residual heat in the hull from heating prior to repair will cause the mix to start curing, you only need a small amount of heat after this point, heating the area around the repair will transfer heat into it without overheating the new surface.

Give it 20 minutes at most and you should have a hard finish, let this cure overnight and wash with acetone prior to sanding on your next visit.

Repeat the procedure to fill and low areas.

Avagoodweekend......
 
Do you have access to the inside of the hull at that point ?
If so - use an infra red or electric bar heater on it to slowly warm up the entire area. Be careful !
Ken
 
Tollesbury Marina just took out a seacock and 2 transducers on Muddy Paws then glassed and gelcoated. All done outside in the freezing cold. The solution was to apply heat to the inside before during and after the work. Outside they used an infrared heater just while the initial cure was going on.
 
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