explore the depths of the crack, without expanding it. If the crack is *only* through the vinyl surface layer, you might not have to do anything about it. If the inner ABS layer below the vinyl is cracked, it needs to be patched.
It is possible to remove the structurally-useless vinyl layer by using a sharp chisel at a very low angle. I would be inclined to do that in order to patch directly on the ABS. Skimming off the vinyl goes fairly easily because the vinyl-to-ABS bond isn't that strong, and because the ABS is much harder than the vinyl.
You could use fiberglass or Kevlar for patching. A couple of concentric layers would do it, using a quality epoxy to wet out the cloth. Don't use any more resin than it takes to wet out the cloth.
It's a bit puzzling why a crack should have developed at the margin of a float bag.
Kayak Carrier Kits
Custom Greenland Paddles
PFD's (Life Jackets)
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