C-Forum

My 10 year old MR Synergy has been wearing through the vinyl, right under where I sit on the triple saddle. For about a year I have been protecting the exposed ABS with 303 or spray paint, but it became clear that the vinyl under the whole area beneath my butt was worn quite thin. I wanted to get a thin patch on the area to take the wear and protect the ABS from UV.

It is possible to apply various patches over the vinyl, but on my boat the vinyl was so gouged and cut that I thought I would rather just remove it. I also have a superstition that epoxy and other "hard" adhesives may stick better to hard ABS than to soft vinyl. Can't prove it, just seems like it might be so.

When putting glass cloth skid plates on an OT Tripper I owned, I removed the vinyl by using a cabinet scraper. But on the Synergy, working on that flat undersurface, I thought I would try a 1/2" wood chisel.

That chisel worked great! It was properly sharpened, and I held it at the lowest possible angle of attack, with the wood handle down against the boat. Pushing steadily, the vinyl peeled away from the ABS cleanly, and the chisel did not cut into the ABS.

In fact, I found that once I had a decent vinyl peeling started, I could often take it in my fingers and pull it away from the ABS by hand. I formed a stronger respect for whoever origninally chose vinyl as an over-skin for ABS. The vinyl is very tough, and the bond is every bit as good as it can be for very dissimilar plastics.

With the vinyl removed from the ABS in the area under the center seat, I took some 100 grit paper and first roughed up the ABS. Then I sanded down the edges of the vinyl so that the patches would lie properly across the transition zone. And I sanded out a ways on the vinyl, feeling that I wanted to see how a glass patch would stick to the viny as well as directly to the ABS.

I cleaned the area carefully with alcohol and dusted it as well. Then I cut two concentric oval 6oz satin weave S-glass patches. I couldn't find the cheap scissors I prefer, and cutting that satin weave on the bias was as hard as cutting Kevlar.

It was 90 degrees in the carport, and it was darn lucky I had the slower West 206 hardener. The larger oval patch went on first, extending well past the skinned ABS area. Satin weave does not wet out easily, and by the time I had the entire patch wet out and laying down, I could feel the epoxy getting hot in the plastic cup in my hand.

I mixed more epoxy, and laid the second patch on top of the first. The second patch extended only a little beyond the skinned ABS area. It started to wet out on its own, pulling excess resin from the first patch, and I brushed on more to get the second patch wet out. Then I worked over the area to take care of resin-starved areas and bubbles.

Tomorrow I will have some serious sanding to do to smooth the exposed edges of the S-glass. Then I will brush on some UV protecting urethane varnish to protect the epoxy.

I could have mixed graphite powder into the epoxy to get the patch to slide off rocks more easily, but I decided not to do that so that I could see into the patch and see how it holds up in the future.

There was perhaps no need for two layers of S-glass, given that the skinned ABS appeared undamaged. And I will have to sand those layers a good bit to get them smooth. But the area immediately under the pedestal seat is a high stress area.

What we really need is something as hard or harder than the vinyl, that sticks extremely well to the vinyl, and that goes on thick so that it replaces wear on the vinyl. Ordinary paints stick pretty well, but cannot be built up in thickness without getting gummy. Then we could just sand vinyl to prepare it, and then apply this magic substance. Epoxy, in my opinion, is too brittle. Ideas anyone?

For a crack through the vinyl and into the ABS on the inside of my canoe, I filled the crack with JB Weld and then glued a 1/16" vinyl sheet over the area and beyond. Using vinylbond, it bonded really well to the floor of the boat. I then glued a vinyl patch with D-ring onto that.

This has got me wondering if vinyl sheets would be a good solution for outside patches, particularly when you're going to be gluing onto the exterior vinyl of the boat. The 1/16" vinyl was very flexible and would bend over a chine easily. I would bevel the edges of the sheet so the edges wouldn't get rocks. Haven't tried this yet, But I'm considering it for a large repair I have to make on a tandem canoe.

Another thought would be to take it down to the ABS and glue the vinyl sheet to the ABS. I'm not sure what glue to use there though.

I've used ABS sheet on 2 (3?) boats now. One was a Viper that I patched the flat wear area under the saddle - I got several additional years out of that boat due to that patch. The ABS was slick, and slid over rocks with less resistance than did the vinyl! I could never figure out how to make the ABS fit the compound curve (right word? Curve laterally and lengthwise) along the chine so I patched those with glass. Not one of my more successful endeavors...

The most recent, is this boat :
http://picasaweb.google.com/scott.broam ... 7190450594

I used tape to hold the ABS sheet to the hull - I won't do that again! Yuck. Not only did not hold it flush, I had a nasty residue to deal with. I used ABS paste to "caulk" the edge. Next time (this week maybe...) I will use sand bags. This was also the boat I injected with resin - the result was nicely solid, yet flexible "enough". We ran it down two rivers (one with rocks, one without) before delivering to it's new home where it will get mostly lake duty.

What happens if you try to prepare an ABS sheet by controlled heating? We used to cook Kydex, a tough vinyl, in the oven in order to get it to lay properly over the stem and stern. Then we would use epoxy to fix the molded skid plates in place. An effective method if done carfully.

Thin vinyl patches are certainly an interesting option if the vinyl gets scraped off under the center pedestal, or maybe even when vinyl has been scraped off the stems as on my MR Guide. I would consider a slow-setting urethane glue, such as 3M Structural Adhesive. I patched a deep scratch in the vinyl about 7 years ago with the 3M, and that stuff is still hanging tough today.

When I ordered my can of ABS cement I picked the brain of the dude who answered the phone - he said ABS was a "200 degree plastic" and went on to explain that was the temperature it "set" at and that you could heat it to that temp and mold it to the desired shape. I tried taking a couple of pieces and heating them in our oven, but when I placed them on the boat, they wrinkled (big wrinkles). Maybe it cooled too much between the oven and garage. I didn't want to go any higher as the edges were starting to brown...

Next bright idea was to boil it as that would have a built in limit of 212. That worked OK for small pieces - I didn't have a big enough vessel for larger pieces.

It did occur to me later that I could have patched the chine with smaller pieces - maybe 2" x 6" laid across the chine, one after the other.

Dan Vallesky (he still out there paddling?) said he made ABS grunch pads my soaking the ABS in solvent (MEK?) until it was soft then just slapped them on there.


I like using the ABS sheet to repair larger areas because it is easier to get a large amount of material on the boat and smoothly - looks nice, less friction. I don't think it adds any more strength than putty.