Is that a gelcoat or a resin coat? Gelcoat is usually harder thicker and more durable but less flexible and more challenging to repair. If it is a resin coat I would thoroughly clean hull with dish soap and hot water. Then wipe down with MEK substitute, or Acetone sand with 120 or 150 and roll on a few coats of epoxy. Many manufactures us vinylester resin. If you want to you can use vinylester but I find the smell overwhelming and epoxy will give you a better secondary bond then the vinylester. The only issue is usually the manufacture wont repair a canoe made with vinylester and repaired or coated with epoxy. Vinylester does not create secondary bounds to epoxy but epoxy can bond to cured vinylester.
Gelcoat polyester type resing is a different beast I know much less about.
If you are only concerned about the cosmetics (which is probably the case since none of the scratches look at all serious), you could just leave it since it won’t really affect the canoe. But if you really want to just clean it up I would first do a little experiment.
On a small part of the scratched surface (say 6 inches square) do a very light scuffing with some medium/fine sandpaper (like 220 grit), followed by a good rub down with acetone or ethanol, and then a light coat or two of a marine varnish (Helmsman Spar would be fine and you can find it almost anywhere).
I bet this will get rid of most if not all of the scratches and will make for a fairly easy, low-cost repair for the rest of the hull, although you will probably be back where you started in a season or two - varnish wont last nearly as long as a resin repair, but is very repeatable.
If what you are looking for is not just cosmetic, then you are probably in a more complicated world involving clear coat, vinylester etc as foxyotter says. I have no experience or advice to share on composite canoe repair beyond basic fibreglass/epoxy stuff.
PS - By “scuffing” with the sand paper I mean just enough to lightly scratch up the surface so that it loses its shine but doesn’t really wear into the surface or generate any significant dust. You are just looking to add a little texture so the varnish will have something to hold onto.
Traveler is probably correct. If you did do a resin coat you would probably want to varnish for the UV protection. Epoxy and varnish work very well combined. I have heard for wood three coats epoxy three coat varnish and you have bright shinny well protected wood more durable then either product alone.
Yeah, that's a skin coat not gel coat. Can you find out from the manufacturer whether they are using polyester, vinyl ester or epoxy? Light sanding and a coat of whatever it was made with would be best. I would never varnish a hull composite hull.
Agree that it would be good to verify what coating you are dealing with, and ideally use that if you want a total restoration.
But it just seems like overkill to apply a full new resin coat to deal with very superficial/cosmetic scratches that are always going to come back through normal use (expensive, would add a pound or two in weight, multiple sandings, time consuming, and many opportunities to go wrong if you haven’t done this kind of thing before).
If the original coating is epoxy, a new coat will need to be covered with a varnish anyway to get the required UV protection, otherwise it will discolour, crack and flake over time.
Assuming a test patch comes out fine, a clear varnish coat or two done in a day inside the garage would be fast, compatible with whatever coating is on there now, and easily removed if a real repair is needed in the future. But obviously the OP’s call.
Thinking about this some more, I have to pull back a bit on the idea of varnish. It probably would help clean up light scratches quite a bit, but the idea that is would be ”easy” to remove in the future is probably overstated. You would need a good sanding to get it all off before applying whatever resin is needed for a more thorough repair.
Aqua-Strip would remove the varnish pretty easily. It dose not matter what resin was used previously. The previous resin is either vinylester or epoxy resin most likely vinylester. The other choice is polyester resin and that canoe is too new and too nice for polyester.
As stated above you can use vinylester resin if you like but it will be a weaker secondary bond then the secondary bond gained with epoxy though that is a negligible difference in situ. The problem that could arise is that vinylester won't stick to epoxy. Therefore if you wanted the manufacturer to do a repair on your canoe and they only use vinylester then they won't repair it. Northstar canoe is that way for one example.
Some epoxy resins do have some UV inhibitors such as 207 / 105 West System and can be hot coated three times with about 3 hours in between coats. I am sure Jamestown, system three, Raka all have similar epoxy. After first coat If you touch the eposy with gloved finger and it leaves intend but does not stick to glove it is ready to top coat and still have primary bond with previous coat. If it is hard wait to fully cure before second coat. The UV protection still is minimal compared to varnish and they recommend varnish top coat. Though my experience is that if it is stored inside when not in use the epoxy will last a long time. If or when it does start to look a little yellow sand it down and thrown on another coat.
All that being said I would say leave it unless you want super shiny then light sand and varnish. If you want added depth of resin for a little margin between that rock and your the fabric or to seal an already exposed fabric then used resin. One ore two coats resin and one or two coats varnish should be fine. Varnish would need to be remove later if you want to re-coat with any resin. Again light sanding old varnish then paint or wipe on Aqua-Strip. Way easier then sanding and doesn't hurt the resin but softens the varnish.
One last note. The smell of that vinylester will blow your socks off with barely a crack of the lid.
Hi and sorry for the delay in replying.
It sure looked like a clearcoat of some kind to me too.
The manufacturer's answer to my query: "your canoe 100% has a clear gel coat on it over a Silver Barracuda cloth."
Apparently clear vinylester gelcoat is put on thinner than coloured gelcoat.
They also layered the kevlar only in required places to keep the weight down as well.
All they're recommending is some very light wet sanding with 1000 - 1500 grit and no varnish.
Then wax if I want it shiny.
They agreed that epoxy will stick to vinylester but not the other way around.
Thanks for all you help and suggestions.
I think I'll just leave well enough alone and blame that mess on the previous owner