Bertram,

Don't sand into the glass if you can avoid it. That will weaken the boat.

An alternative repair would be to remove all the varnish from the bottom and apply a graphite/epoxy mix. It'll be more scratch resistant than varnish. It's also less work to touch up and it's completely UV resistant.

Laszlo

Thanks Laszlo for the quick response.

    I hadn't considered graphite.  I guess it wasn't commonly used a few years ago or else I thought natural wood was more eye pleasing, not realizing how much abuse we would put the yaks through.  

  I searched this forum and found most of the answers I need to proceed.  This is my plan.

  1. Sand off varnish from bottom only. Break the gloss only on the remainder of the kayak.  I plan to use a DA 180 grit on bottom and water sand 240 grit on remainder.

  2.  Fine line mask off everything above the sheerline.  Apply two coats 24 hours apart of 1:1 mixture graphite + MAS low viscosity epoxy, slow hardener.

  3. Is sanding the bottom at this time usually necessary?

  4.  Mask the bottom below sheerline.

  5. Spray 2 coats of Interlux perfection Varnish.

Does this sound reasonable?  I don't want to make a mistake.

Thanks,

Dennis (Bertram 28 is my other boat)

Sounds fine, Dennis, except that you mean chine, not sheer, right?

I didn't sand any of my graphited bottoms.

Laszlo

Dennis 

I used the same varnish on my kayak and plan to re coat it after a years use with the same. A couple of the deep scratches will have to be sanded out down into the glass cloth to repair just like yours. You shouldn't have to completely remove the old varnish on the bottom if you go back on with more of the same most of the scratches will fill with a fresh coat of varnish.

I was suprised how many little scratches it got in the first month but I really like the bright finish instead of going with a black bottom. Since I need to work on my wet entry and exits anyway the plan is using a small sanding disc in the dremel to take out just the damaged cloth and glue a small patch of cloth back in place building up the surface to prep it for varnishing.  I don't believe graphite powder in epoxy alone will provide enough UV protection without varnish a over it, that would only prevent you from seeing the yellow. I have used the SB 112 epoxy that is suposed to have a UV already in it if I was going to do a graphite bottom like LAzslo suggested I would use that.

Good luck,

Charlie

As far as graphite/epoxy UV degradation, I know builders in Florida who leave their boats outdoors 24/7. If there was no UV protection, the bottoms should get chalky in about 6 months to a year. Some of the bottoms have lasted 5 years with no sign of chalking, so there's at least enough protection to last until the next set of scratches, especially further north and if the boat is kept out of the sun between uses.

So there's no reason to avoid graphite/epoxy for longevity reasons. Esthetic reasons are up to the individual builders, of course.

Laszlo