I followed those posts. While several people did this and documented it. No one came back and said it worked. I even asked one of the guys and never got a reply.
I noodled the top 12 inches (30cm) years ago. In a test with my son we flipped the boat in 4 feet of water. We were mainly just interested in the practicality of flipping and getting back in. It came nowhere near turtling, but we were able to get to the centerboard and right it in less than 15-30 seconds. It has a large righting force just at where the centerboard tip is submerged and no one is in the boat. Its pretty happy to just sit there on its side as well.
Ive always wanted to tie it up to the docks and let it rest on its side for several minutes to see what happens. In the shallow water test the boom actually is what is pulling the mast under. With the sails down, the boom points directly to the mud. it fills with water and then is dead weight. Never put an end cap on the boom. You want that water to rush out ASAP as the mast lifts up.
Its pretty warm here. On a calm day ill head off to the beach launch area and see how long it takes to turtle.