For your first repair, I'd stay away from the heat gun and use a plastic welder (soldering iron). If you hold the heat gun in one place too long it can overheat the hull and start melting it, making your small hole a large one in an instant. whichever method you try, keep a cold damp rag handy to slap on the repair and cool the plastic should it overheat. You'll need some plastic to fill the holes, HDPE. A Home Depot bucket is HDPE and its even Orange. Cut a strip about 1/4" wide by 6" long. Hold the end over the hole and push down with the soldering iron. as the strip melts, it will sink into the hole. Then make some small circles with the soldering iron to meld the plastic. Repeat until its built up above the surrounding area then let it cool. sand it down nice and smooth and happy paddling!
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