Question 1

If you take a wet towel across the scape does the white go away?

I repaired my kayak with several deep scratches on the hull and sides.  In one case I had long "white" scratches on the bottom.  I used 80 grit orbter sander to grind down and feather the area without cutting into the fiberglass.  I then coated a new thin layer of epoxy and used the orbiter sander and a fairing board to smooth out the hull.  Of course worked the sander up to 180 grit across the entire hull, and then re-varnished.

On the deck I had a scratch that went into the fiberglass about 1/2 inch wide by 4 inches.  I sanded out the area and actually got down to the wood a little bit.  I feathered the edges and laid in new fiberglass, resanded and feathered the edges with several coats of epoxy, and again more sanding.  You cannot tell that is was patched.

Question 2

It would help maybe to have some pics.  But it sounds like you have fiberglass separation.  If so you need to cut out the fiberglass with a razo rblade box cutter or other sharp knife.  Again sand and feather the edges.

Question 3

Again I would sand down this area but do not cut into the fiberglass.  If this doesn't solve the yellowing,  you can remove the fiberglass from the entire boat or partial area with a heat gun.  Nick Schade, Guillemot Kayaks, has a YouTube video on how to restore an old boatby using a heat gun and putty knife.

Of course it will be your decision how much effort you would to go to restore your canoe.  Some patina definitely gives some character to your canoe assuming it doesn't leak and has a smooth hull.  https://www.youtube.com/watch?v=BHNHXD-g2N0

Nick's video

dogger54 - when you repaired the scratches on the hull and sides were they into the fiberglass?  if so did your repairs get completely rid of them or do you still see the white cloth?

I had two situations: The scratches on the bottom came out with an orbiter sander without hitting the fiberglass.  I then just re-apply additional epoxy and feather sanded.

The scratches on the deck were down to the fiberglass.  I had to sand down to the bare wood on one section about the size of a quarter.  Of course this removed the white scratch marks.  But again I feather sanded the sides and then apply two layers of fiberglass.  Now how you layer the fiberglass is important for strength.  When sanding fiberglass you do not want be cutting through layers of your patch due to strength reduction.  So you lay the fiberglass largest patch first.  (I know you are probably thinking to fill the low spot with a small patch first).  You cut this patch big enough to fill the low spot and extend it beyond maybe an inch or more for feathering the edges.  If you still have a low spot add another layer of fiberglass smaller in size to remove the low spot.  Sand feather the edges and re-coat epoxy.  I will tell you use a 80 grit sandpaper to do a good job in feathering the edges of the fiberglass.  You cannot tell where this patch is today!

 If you move to 150/180 grit too soon or you are using dull sandpaper disk, you could buff the fibers and will not clear out with epoxy.  This due to the buff action and heat apply to the fibers.

I've never done a restorization. Would it be too much work to use heat and remove all the glass so you could sand the wood and add a single layer of glass with epoxy? I'm assuming that you can do this with polyester. Perhaps it only works with epoxy.

Keith

You have to decide whether its worth a major restoration or not.   But, the above Youtube video from Nick shows you how to do it.  I have used numerous of his video in building several kayaks and they are top notch!

You can remove polyester/fiberglass.  Here is how someone did it, which I think is very similar to Nick's video:http://www.rotdoctor.com/zine/rbremovefbg.html

These guys in the video were doing a huge boat.  I still think a standard heat  gun would work on a canoe.  Of course for safety I would wear a organic filter mask.

If you decide to do a major restoration I would use epoxy/fiberglass and not polyester or even vinylester due to is low durability, excess weight, and an lower tensil strength compared to epoxy/fiberglass.  I have had great success with the MAS products.

Removing the cloth is a pains taking messy experience.  One option is cut the ofending area out wit a VERY sharp razor...apply cloth patch ...feather...resin then varnish.  Keep your classic work it is part of the beauty of a hand crafted craft.

Thanks fellas.. Based on what I am hearing it sounds like a sanding and patching on the bottom of the boat will work well.  The possible delamination on the bow tip needs a closer examination.  If the layer next to the wood on the bow stem is beginning to detach I may have a lot more work cut out for me.  I have been reading about the use of epoxy resin vs. polyester resin.  In some cases it looks to me like the builders are only using one layer of cloth of the bottom of the boat when using epoxy resin, rather than two layers as done with polyester resin.  Is this standard to reduce the number of layers when using epoxy and how would this translate to fiberglassing the bow stem?  We used 4-5 narrow layers on the bow stem and in case I need to strip down to wood on the bow, can I get by with less layers on the tip of the boat if using epoxy?