I just recently got a mohawk viper 12. everything is good on it except the center hull. from the inside there is no damaga but when you flip it over its pretty bad. how would you go about patching? its a royalex canoe if that helps. Also whats the best type of glue for knee pads, the saddle etc…i heard vyna bond and this h2o water glue from NRS.com…i found some patch kits from oak orchard canoes for the hull. sny suggestions or tips would be greatly appreciated. i can supply pictures if needed
Hull repairs
You don’t describe the type of damage to the hull, but I suspect from the location is is simply wear on the outer layer of the Royalex. If it has not worn through into the core, don’t worry about it. The wear is mostly cosmetic at this point. If it has worn to the core then you may want to patch the worn area with fiberglass and epoxy.
If that is the case, clean the area to be patched using lacquer thinner and then sand lightly with 120 grit sandpaper. Cut a piece of 6 oz. fiberglass cloth the size of the area to be patched. Lay the cloth over the area to be patched and saturate with epoxy resin. Once saturated, squeege off any excess resin. If you want a smooth surface (more for cosmetics tan for function) apply two or more additional coats until the weave of the cloth is filled. You can also sand the patch after the resin has cured with wet/dry sandpaper until smooth.
For a neater patch, mask the surrounding area with poly sheeting. Don’t mask with paper as the epoxy will soak through and bond it to the boat. Remove all masking before the epoxy cures. It can be murder to remove the tape after.
Some authorities claim that you should flash the surface to be patched with a flame prior to applying the patch. It supposedly does something to the surface of the plastic that allows the epoxy to chemically bond better. I’ve generally done this and never had a patch come loose. This is done by simply flashing a propane flame over the surface quickley. Do not hold it for any length of time in one place or you’ll melt the Royalex. Simply pass the flame quickly over the surface. You will not likely see any visible change in the plastic as you do this.
As to adhesives. For pads and other foam items, Barge cement or Pliobond works well. For items that will be under tension such as D rings use 3M urethane structural adhesive available from NRS. Vinabond is great for adhering D rings on vinyl patches.
Marc Ornstein
Dogpaddle Canoe Works
Custom Canoe Paddles and Cedar Strip Canoes
hull repairs
good information…i should have described the wear a little better. most of it is just normal wear and the outer paint is rubbed off…there are two spots that are deep and one is down to the core so i will follow your directions for those…should i just use some royalex spray paint for the other spots to stop more wear?
Hull repairs
The top or colored surface is not paint. It is the outer layer of the Royalex. Aside from abrasion resistance it also provides UV protection to the rest of the rubber/plastic laminate. Small scrapes can be touched up with any good automotive enamel. A deeper scrape might be filled with epoxy and then painted.
Marc Ornstein
Dogpaddle Canoe Works
Custom Wood Canoe Paddles and Cedar Strip Canoes
this works great too
I’m mattm over there and can vouch for the abs/acetone method. Repair holds up to seal launches quite well 
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Paint
Paint works great until the next time you run it over some rocks. The outer layer of a royalex hull is vinyl bonded to the ABS underneath. That holds up far better than any paint I’ve seen. ABS doesn’t like UVs so covering it is good. If you rely on paint better keep the can handy (or stay off of the rocks!). Otherwise plan on storing your boat out of the sun.
Hal’s modified voot voot method
When I was a young fella, we used to buy this stuff called p-tex, which was used to fill scratches in skis. It was basically a thin rod of polyethylene which you light on fire and the drips of burning plastic fill the void. After, you would use a razor to trim the excess.
About the same time of life, we would go out in the woods armed with trunkloads of bailing twine, donated by farmers who didn’t want it but couldn’t bring themselves to throw it away. We would hang from tree branches, 20 feet in the air and weave nets from the twine, forming huge spiderwebs through the forest. These were great fun; we learned to run across them, only occasionally stepping through the cheap weave and landing flat, 20 feet above the ground. We also learned to light six-pack rings on fire, listening to the melted drips plastic as they dropped, making a voot-voot sound as they went. This of course progressed to milk crates and anything else that would burn. Well, bailing twine and napalm-like substances don’t mix well and there wasn’t one of those nets that survived without burning up.
So anyway, my brain being permanently scarred from my childhood, I took a plastic flower pot, the chewy black kind that trees come in from the nursery, lit strips of it on fire and dripped it onto the bottom of my boat. As I worked, I saw that I could actually lay it on as it burned instead of letting it drip, forming a much smoother layer. Then I took a block plane and smoothed it off. It came out like hell, got brittle. Why are you taking advice from a mad man?