Hairline Crack in Vinyl and ABS

milkman · Post by **milkman** » Mon May 28, 2007 5:48 pm

A hairline crack about three inches long has just appeared on the inside bottom of my canoe right before the seat. It looks like it goes through the vinyl and part of the ABS. The exterior of the canoe is fine. I'm wondering what is the best way to repair this crack. I will need to reinstall a vinyl patch with D-ring after repairing the crack. Should I:

1. Sand it down to the ABS and coat it with a mixture of ABS dissolved in acetone ... then install the D-ring.

2. Fiberglass it and then install the D-ring. (My concern here is that the fiberglass will eventually crack too as the canoe continues to flex at this point.)

3. Just install a big vinyl patch that covers the entire crack and then some.

The canoe at this point shows no soft spot at the crack and I appear to have caught it at its first appearance--I think water seapage into the ABS is minimal. As soon as I got home, I dried the area with hair dryer.

Any advice, especially with experience to this time of crack and a fix that worked, would be appreciated.

yarnellboat · Post by **yarnellboat** » Tue May 29, 2007 5:46 am

More later, but read these:

http://cboats.net/cforum/viewtopic.php? ... age+cracks

Out of curiosity, what kind of boat is it? My friend's Outrage has also cracked.

Cheers, Pat.

Jim Michaud · Post by **Jim Michaud** » Tue May 29, 2007 2:41 pm

Milkman: I would go with choice #3. From my experiences I've found that the boat will crack again along the edges of fiberglass or Kevlar patches. This doesn't happen with vinyl patches because the vinyl is so flexible.

I haven't tried the ABS trick on the inside of the boat yet. I would think that you would have to put a fairly thick layer of ABS in order to prevent cracking again. This would interfere with your D-ring patch.

Jim

mshelton · Post by **mshelton** » Tue May 29, 2007 2:46 pm

ADHESIVE!!!

milkman · Post by **milkman** » Tue May 29, 2007 3:36 pm

For inside cracks the best solution I found was pretty simple - First take a 12-16 penny nail and de stress the end of the crack by drilling a small hole through the top layer of vinyl. Then apply a vinyl patch. You can often find sheet vinyl in old fashoned hardware stores or if you have a plastics shop in your area. For inside patches I use the thinnest I can find. Vynabond the patch into place like you would a dring. I have also found the grey sheets they use for shower pan liners (to waterproof before they lay tile) to work quite well although it is a bit thicker than you need inside - it is good for worn chines or bow and stern wear areas. The grey PVC can be found at your building supply places and even Home Depot.

I like Jim P's advice in the old thread. A vinyl-sheet patch sounds like a good solution.

The boat is a Dagger Phantom. A canoe I bought used and have abused on many a rocky run. It still is in really good shape though, except for that crack. Yesterday I noticed an even more hairline one underneath one of the air bags, so I may be looking at lots of patching practice as this boat gets older.

Thanks for the advice and the link to the old thread.

philcanoe · Post by **philcanoe** » Wed May 30, 2007 12:49 am

A quick search of ABS Solvents returned several hits, among them the following two links:

1st from Grumman-American Pilots Assoc:
http://www.aya.org/aya.aspx?pgID=1021

2nd from webbikeworld
http://www.webbikeworld.com/Motorcycle- ... s-bags.htm

They both are concerning using pre-made commercially available ABS Paste, available in the plumbing section of most (larger) hardware stores.

Post by **sbroam** » Wed May 30, 2007 3:44 pm

Phil -

That is some great and, for me, timely info. Never really thought there might be other folks using Royalex...
Thanks!

Scott

ezwater · Post by **ezwater** » Fri Jun 01, 2007 2:14 am

I would not give up too soon on the cloth and epoxy option. But FG should NOT be used for an inside patch. Use Kevlar instead, and lay it in with West epoxy. The largest of three pieces of Kevlar goes on first, then the next smallest, then the smallest. Even the smallest piece should be larger than the long dimension of the crack. Three layers are enough given that the crack seems not to go through the inner layer of ABS. It is probably not necessary to remove the vinyl layer, as long as the surface preparation is good.

The hull will NOT break at the line of the patch because the transition zone is "soft," just a single layer of Kevlar.

I was bothered by some of the advice I read above, such as exposing the ABS to Vynabond. One does NOT want to do that. ABS may undergo unwanted softening from the solvent in Vynabond. A vinyl patch is quite safe IF and ONLY if the vinyl layer on the ABS is intact. Any crack, any drilling, or scraping away, makes the ABS vulnerable to damage from the Vynabond solvent.

milkman · Post by **milkman** » Fri Jun 01, 2007 2:32 pm

Thanks, ezwater, for the advice about not getting vinylbond on the ABS. I still like the idea of doing an vinyl patch since most of what I will be bonding to is vinyl. But because of your warning, I think I will protect the small amount of ABS exposed by the crack by either filling it with some epoxy or JB Weld. That way no vinylbond will get into the ABS when I lay down the patch.

milkman · Post by **milkman** » Tue Jun 12, 2007 3:32 pm

Here's what I ended up doing:

1. Drilling to stop the crack's progress.
2. JB Weld over the crack to keep vinybond from getting it and melting the ABS.
3. A light sanding of the JB Weld area to level it and expose as much vinyl around it as I could for gluing.
4. Gluing a 1/16" thick patch of vinyl sheet onto the area with vinylbond and then heating it up with a blow dryer to really cement the bond. I bought both 1/8" and 1/16" thick sheets and the 1/8" seemed overkill and like it would be too stiff.

The result seems to be a really solid patch with lots of flex because of the 1/16' thick sheet. Now the trick is going to be gluing a D-ring onto that for my thigh straps. This should be a good test of vinylbond and my gluing abilities as gluing a D-ring onto the patch will double my points of failure.

I'll post another message if it fails at any point.