For some time now I've put some thought into a suitable way to go about repairing a damaged plug-in cart scupper hole on a Hobie kayak. While not terribly common, it's not impossible to inadvertently damage the scupper hole tube, especially if your kayak cart does not have rounded end caps on them, and particularly if there is no end cap at all.
Its clear to see in the photo below that the damage shown was caused by a cart that A) did not have a rounded end cap fitted and B) was not being used correctly.
How do I know this? That semi-circular puncture is precisely the same shape as the rim of a 25mm kayak cart post and is a fair giveaway. I also know because the kayak in question is mine and I know what occurred to create the problem (one of the end caps popped off, I neglected to replace it and a rather slap-dash job at inserting the cart resulted in this). I was pretty relaxed about it at the time... so much so that I didn't even bother to check it, even though I knew it might be damaged. But when I soon started noticing excessive water inside the hull (a few litres, nothing to fret about) after a few hours kayaking, I knew for sure I had a problem. Sure enough, when I looked closely I found this. Believe it or not, however, I was still pretty chilled about the whole thing, even while knowing it wasn't a legitimate warranty claim. That's because I was confident in the repair method I'd been thinking through long before this occurred. In fact, I was actually planning to implement the fix as a preemptive strike anyway, to prevent such problems from ever occurring.
So this is my first attempt at repairing a badly damaged scupper hole and although I'd do a couple things differently next time around, the fix appears to be pretty solid and is now unlikely to ever be a problem again... even if I repeat the same negligence. Here's what I did...
The basic plan in place was to use a brush of some sort to strengthen and protect the scupper tube, bonding it in place with some sort of glue that I figured would do the job. I settled on Marine Goop for that. What was a little trickier to decide upon was what to use as a brush. At first I was eyeing off some poly-pipe with an ID (internal diameter) of 25mm. The main problem with this was that it left spase room for the cart posts to slide into - too tight-a-fit. Ironically I found a solution in a broken Hobie paddle... the shaft of which was the ideal ID and fairly suitable OD. It fit reasonably neatly into the base of the scupper, but would not pass through the top section, which is thicker. That was fine by me though - it was the thinner parts of the scupper tube that was breached and in need of sealed reinforcement.
Using a hacksaw I cut the broken paddle shaft into 2 x 7cm sections (in hind sight, 6cm length would have worked better). Employing a dremmel to clean up the rims, I also used it to grind down a 45 degree radius on the inner rim of the each end (to help guide the cart posts into the tube). Then I used a course sandpaper to scour the outer surface of the makeshift paddle-shaft brushes, then using the same sandpaper, scoured up the inside surface of the scupper tubes. Then I cleaned both off with metho to insure the best bond possible.
Smothering the outer surface of each brush with marine goop, I then pushed them in as far as they would go from the bottom, with the edges pushing up hard into the thicker section at the top of the scupper. To achieve a neat tight fit, I heated up the plastic of the top section with a heat gun first, which allowed me to work the brushes a mm or so higher, wedging it tightly into place. As you can see from the image below, there was almost a centimetre of brushing tube poking out once done. This was a miscalculation and choosing 6cm length would have resulted in a better finish. Rather than taking it out and resizing them, I opted to simply grind them back using a dremmel. This worked out OK, but did expose an error in my technique. Grinding and sanding the edges back to the base of the hull exposed a few air bubbles in the goop, which has everything to do with applying the glue to the outer surface of the brushes instead of the inner surface of the scupper. I'd do that differently next time, as sealing the air bubbles made for a slightly less trim and terrific finish. Despite this, it's integrity is sound and although a tighter fit, it's still pretty easy to slide the wheelcart into place.
Had I done this before inadvertently damaging the scupper, I doubt the damage would have occurred in the first place. The truth is, however, had the cart had rounded end caps inserted it wouldn't have happened either. Regardless, I was always going to get round to doing something like this sooner or later... just so happened to be later in this case.