This is a sign of sun damage. As a kayak fades, or begins turning white, the plastic loses elasticity and its structural strength.
Two ways to test a crack (to see if it worth trying to repair):
1: Push down on the plastic at the end of the crack. If the crack expands then the plastic is too brittle to weld.
2: Grab one edge of the plastic with pliers and bend the plastic back. If it snaps before you bend it 90 degrees then again it’s too brittle to weld.
Flip the kayak over and inspect the hull. Pay particular attention to the drain (scupper) holes. If the drain holes don’t have obvious cracks or welded repairs look even closer. There might be cracks that haven’t separated yet (they look a bit like stretch marks on a person’s skin).
These types of cracks occur because the owners or previous owners sat in the kayak while it was on the beach or it could have been kids stepping in the seat. When there is weight on the drain holes in the cockpit from someone sitting or standing on them, the drain holes are being shoved out the bottom of the kayak because the hull is being supported by sand and the scupper holes are higher than the bottom of the hull.
We do not warrantee welds on plastic. The plastic cracked because there was too much stress on that area and a weld is only 50% as strong as virgin plastic. The stress that cracked the plastic in the first place is still there so weaker plastic (a welded repair) will crack with much less effort.
Stern Drag Holes
Look for uneven wear on the keel at the rear of the kayak. If you notice an uneven flatness to the plastic press on the area and see how thin it is. By the time a hole appears, the plastic is super thin over a larger area and when we try to weld it the hole expands and becomes much larger.
People will drag kayaks if they don’t have anyone to help them carry it to the beach. Most often across the grass and down the beach but we also see people drag kayaks over cement and across roads too. If you pick up a kayak by the bow handle and drag it, it will sand away at the bottom rear of the kayak.