Six years later and the boat is still fixed.

One more thing… to me, sawing a perfectly good boat in two is a crime, unless that’s the only way you can get your boat to a special piece of water!

If you're repairing a cracked fiberglass panel, as opposed to fixing a hole, it's hard to get the cracked edges to line up on the outside so the repair will be invisible after painting. The trick is to run a smallish drill bit along the crack to clear away the fractured edges and leave a narrow gap. If the edges are bent out of shape press them back into place with a board or other form protected from bonding to the resin with a covering of waxed paper. After structural repairs are finished on the less visible side, Bondo will fill the gap smoothly.

An old boat repairman's trick to make the fiberglass mat patch blend in with the surrounding area (if it will show-- which it doesn't in the repair on the jet ski): Tear the mat, rather than cut it. The torn edge tapers to nothing while a cut edge is abrupt and will show more obviously as a patch.

If you add enough fiberglass mat on the back side to make your patch strong enough there's no need to add more fiberglass on the front side. Use Bondo to fill the hole on the front. It can be smoothed with a putty knife and easily sanded flush with ease after it solidifies, which only takes minutes.

The G/Flex Epoxy is impressive, although I'm not sure how well it would work on brittle plastic. In my experience, sun-weakened plastic that falls apart by on its own holds together when bonded to foam. With G/Flex alone, my kayak would shatter if dropped on its "sunburned" side.

Also, G/Flex is expensive. The kayak in the video looks to me like it has $50-worth of the stuff on it. The kayak repair I did cost $5 for foam and about $1 worth of a $12 tube of roof goo, the rest of which I used on a roof. For a new boat, G/Flex would be worth it. My boat was a basket case I rescued from a dumpster.