Using my old whitewater kayak, aptly named “Frankenstein”, as a prototype, all we needed was HDPE (plastic) to create our mate surfaces from. That would seem to be an easy task, right? Just go to the local store, grab some HDPE and head home to make a boat, piece of cake. Right.
After much research, I found a source on the internet for slabs of the stuff and had it delivered. While we were waiting for delivery, I decided to design some special clamps that we needed to lock the boat sections together when we paddled it. A friend of mine, Al Guk, has a machine shop and he was nice enough to whip up the four I needed. (Thank you, Al!)
When the plastic arrived, we cut it down and shaped it to make the interlocking tongue and groove profile we wanted. Then, all we had to do was bend it from the flat HDPE that we bought to the round shape of the kayak. This was the “fun” part! We needed to make a mold that copied the shape of the hull, could be heated to 350 degrees, and we could press our new pieces into. With a few cardboard templates, some plywood, and a jig saw we were in business.
To get everything to the right temperature, we used a “salamander” commercial heater and a truck toolbox as an oven (right in the middle of the driveway!). An old oven thermometer told us when things were up to temp and it was time to press it into shape. It took two of us for this. I used welder’s gloves to grab the hot plastic and stuff it into the mold while my wife, Zin, ran the log splitter we used to press it into the mold. (Take a second to go visual, it’s worth the laugh!) Once we had the mold closed, we stuck it back in the oven to heat back up and give it time to accept its new shape. We let it cool down and kept it in the mold for a day or so before we pulled it out and fit it into Frankenstein.
It fit in beautifully. All that remained was to weld the piece into the boat. Plastic welding is a lot like metal welding in that you melt two pieces of plastic while you stuff a thin rod of the same plastic into the melted plastic. There is an art to this and I was a rookie; it wasn’t pretty but it worked.
With all that done, we screwed the clamps in, tucked the gasket into place and took good old Frankenstein out for a test paddle. Believe it or not, this crazy process worked like a charm!
A nice strong connection and dry as a bone! There was no difference in paddling the boat at all.