Perhaps the same way folks repair big holes in kayaks would work. I have watched some videos where people heat up the kayak and a piece of plastic with a plastic welder or a heat gun and plastic weld the kayak. In some of the videos they add some wire mesh to strengthen the patch. Perhaps something along those lines would work. Rather than patch a hole, add a layer of plastic with some wire mesh as part of the layer.
I plastic welded a hole shut (where I removed a rivet) with a plastic welder. I cut a piece from a 5 gallon bucket for the patching material.
I am not sure if this is a good idea for that location, perhaps someone from Hobie can comment.
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Fish tremble when they hear my name
A ship in harbor is safe -- but that is not what ships are built for.
--John A. Shedd, Salt from My Attic, 1928