Gel-coat. And gel-coat only.
I have a GRP/kevlar sea kayak, and am always looking at other canoes and kayaks from Sydney Harbour to the Macquarie River. 'Painting' does not ever work, AFAICT.

'Gel'-coat is a perculiar name, though; it dries very hard, and is about 0.5mm thick when set. I'm scared to touch the stuff, though.

Depends on the value and use. two pot polyurethane is the best, harder and more water proof than gelcoat. Expensive and may overcapitalise a cheap knock about canoe. If its a cheapy and going to get scratched I would use White Knights oil based paving paint!

Firstly DO NOT use gelcoat. Gelcoat is designed to put on a mould before you put the glass fibre on, it does not paint well at all.
Flowcoat will paint well and it was you see on the inside of most production fibreglass boats. Although flowcoat is easy to paint and very wear resistant, it won't flatten like modern paints so if you want a great finish don't go there.

As the above poster said, International Brightside (renamed now but any good boat shop will know the stuff) is a great single pack paint. It recommends using the primer, undercoat and topcoat but you can get away without the undercoat as long as you make the topcoat thick enough to hide the grey primer.

Also Jotun make a good two pack system which uses an epoxy undercoat/primer and the a poly top coat.

Hope that helps

As discussed above, do not use Gel Coat, use flow coat if you want a shinny finish then spray wet and dry and polish it will look like it came out of a mould.

It is how ever easier to use two pack paint, although not quite as wear effective as flow coat, it is good.

Use single pack paint if you take really good care as it will scratch the easiest.

andrew1996 said...

Where can I buy Flowcoat?

Any fibreglass resin supplier will have it, its sold by weight but you don't want it. Flowcoat is the flat finish applied to the inside of freshly laid up glassboats. It has wax added to give a non sticky finish to the previous layup which would normally stay sticky for a few days after it goes off. It hides the csm fibres and gives a cheap easily obtained finish on production boats. Its heavy, not very water proof, wont stick to old fibreglass and not all that cheap. Gel coat is the shiny outer coat applied first to a mould. Then a normal production boat is laid up with csm and resin, sometimes cloth is added. Then flowcoat is applied as soon as the last layup goes off and has to be less than 24 hours.
Some people try to use gel coat for refinishing but this is a poor choice as well. Heavy, brittle, not that waterproof and difficult to apply smoothly.

For the same money you can spray your canoe in two pot polyurethane.

Peruse this site for similar problems;

forums.sailinganarchy.com/index.php?/forum/56-fix-it-anarchy/

Wollemi said...

Gel-coat. And gel-coat only.
I have a GRP/kevlar sea kayak, and am always looking at other canoes and kayaks from Sydney Harbour to the Macquarie River. 'Painting' does not ever work, AFAICT.

'Gel'-coat is a perculiar name, though; it dries very hard, and is about 0.5mm thick when set. I'm scared to touch the stuff, though.

Hi Wollemi, I have used two pack paints and flow-coat but never Gel-coat.

The fact that you can apply it 0.5mm thick sounds very good for a kayak, since they often get knocked about around rocks etc. Didn't know it was an option.

If you, or anyone else here, have applied Gel-coat to a large area of hull (post-construction; so not whilst in the mould) to a boat or kayak or other, could you say how you go about it?

Eg. do you apply it by brush or roller? Can you mix, say, half a litre at a time?
A how do you thin it enough to apply and get it to flow and even out reasonably smoothly on a vertical surface?

I am not looking for a method to achieve a showroom quality shine; just a reasonably acceptable surface on a well-used kayak or canoe.

Thanks.

I am confused now, do I want Gel Coat of Flow Coat or something else?

Karsten said...

andrew1996 said...

I am confused now, do I want Gel Coat of Flow Coat or something else?

I agree with the advice you received above. If we set the Gelcoat option aside for a moment:

1) One-pack marine/automotive paint like Brightside (most commonly used; easy to brush; levels out to a nice smooth and shiny surface)

2) Two-pack marine paint, most often two-part polyurethane (more expensive, longer lasting, harder, mostly sprayed, but some can be brushed; levels out to a smooth and shiny surface)

3) Polyester flowcoat: (much thicker, quite hard, does not even out to a smooth and level surface - so you would not want to use it on your car or anything you want to show smooth lines)

Those would be your "standard" options.

Gelcoat is normally used at construction time, and I did not know that it is a viable maintenance option. Some of the experts on the forum will hopefully soon explain whether the Gelcoat approach is viable, and if so, how to apply it.

No. Gelcoat is often used for chips etc. Most repairs on quality yachts will be two pot. Yachts that have faded gelcoat usually get sprayed in two pot or single pot polyurethane. I have seen a yacht redone in gelcoat and its not a pretty sight!

Ramona is right on the ball. Had a few chips here and there. Went to fiberglass supplier with over the counter sale. /In Center Rd. in Mel./ Gave me FLOW-COAT.
white - fix the hull, tinned - fix the deck.
Hard as a rock, you can sand it, drill it.
'Rough as', would not dare to use it as a top coat.