: . I suspect there
: will be a problem with one of the seams.

I suspect a poorly glued or sealed seam too.

Easy to check by putting duct tape or packing tape over the deck seams and going for another few paddles. If you are still getting that much water then the leak is at the ends (one or both) where the fabric was slit and glued back together for à tight fit.

Find a store that sells swimming pools. They have a clear vinyl patch material for above-ground pools. Cut a piece about 4 inches wide and as long as you need, and use that to seal and reinforce the ends. In 3 or 4 years you can reskin the boat. In the meantime keep it handy as a loaner for boatless friends who might want to try kayaking.

PGJ