... just below the weld. Definitely under designed, and metal fatigue. Maybe the heat from the weld was a factor in weakening the metal there.

The whole design is bad news, even if it had been made strong enough. Too much weight up high, too much windage, and a big problem for a boat in a seaway with any serious wave action, IMHO. All for the convenience of dinghy deployment. Maybe OK for sheltered waters, but even sheltered waters (e.g. Chesapeake Bay, Cape Cod Bay, LIS) can see some serious motion. (I've sailed in 6+ footers in LIS with wind coming down the length of the sound, and it wasn't fun.)