Again, there are very few adhesives or patches that will stick to polyethylene. There are a few expensive adhesives made for low surface energy materials I can tell you about you if you want. But I believe the best way to repair this is from the outside via plastic welding.
Hobie sells a plastic welder for hull repairs. This might work for this purpose as long as the damage is not too extensive.
You can get one
here. And
here is a YouTube description of the welder.
Even though Hobie provides color matching plastic rods, don't expect the repair to blend in perfectly, it'll show. But welding (melting) new material to the hull to reinforce the damage is probably the best way to repair it. You may also wish to talk to a local kayak dealer to see if there's anyone near you who does this kind of repair if you don't feel comfortable doing it yourself.