Shear Force
Published January 9, 2009 | 
Today was the day I think I finally repaired my cockpit combing. Up until this point none of the old ways would work. It was simply an issue of force. The problem was finding an adhesive that worked. While epoxies may solve some problems this was not one of them. What did work in the end was a product called Plexus MA 310.
In late 2007 I had a unique crash that caused a large amount of weight to press down on my combing to the point of crushing one side of the kayak and although I didn’t know it at the time, it also weakened the attachment of the combing to the hull on the opposite side of the crush. I imagine the opposite side did not break loose since the crushed weaker side was taking the pressure. Well, once I finally dug in and did a solid repair on the crushed area and it was totally solid again, the weakness on the other side came though. Snap! My combing detached along about 18 inches of the hull. Blast!
Now here is where the problem came up. Most adhesives work fine when you ask them to hold something together. When they are meant to resist or adhere against a direct pulling or perpendicular force. That’s why superglue will hold up a truck. Where you run into problems is with “shearing” forces, when the items glued together are pulled parallel to each other or twisted. Most “hardware store” epoxies don’t do well against a shearing force. You need something designed to take that kind of pressure.
The combing was originally attached with something called Methacrylate glue. I could have had some sent to me from Rockpool but It seemed silly to have it shipped all the way from the UK if I could avoid it. And that’s the real reason for this post. I asked around and with the help of Brian Day and Jon Stackpole at Rutabaga I found that Plexus MA 310 is available through a place called Jamestown Distrubutors. So bookmark their website because there are not many outlets for Plexus.
The repair itself was simple enough. Just clean the area, mix the Plexus, spread it all over, and clamp. Wait 35 minutes and that’s it. Since then I’ve been pressing, standing, and beating on it! Finally, I think we’ve got it!
Oh, and by the way. . . if you are going to live with a kayaker you may as well accept that some repairs may be done on the dining room table!
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2 Responses to Shear Force
I’ll certainly bookmark that tip Derrick with my Rockpool soon to travel to Norway on 3 planes and through 5 airports this time!
I know what you mean. Mine got one nice chip from the first flight but it held up against the airlines pretty well. Now other kayakers. . . that’s another story! LOL!