Encapsulated or Bolt On Keel?
I am not sure what the photos indicate about bolt on or encapsulated keels. The keel stub failed at the hull above the keel joint and not at the keel bolts or athwartship frames. This is an area of the boat where a failure could have occured with either a bolt on or encapslated keel. In some whats a bolt on should do better in this kind of situation since a properly engineered bolt on keel has a lot more structure (athwartship framing) than an encapsulated keel. (That athwartships framing in one of the disadvatages of a bolt on because it prevents having tanks in the bilge as easily as you would with an encapsulted keel.
This accident was actually pretty widely discussed on the internet a while back. It is my understanding that the failure occured in an area actually above the keel joint where there was a large section of rotted core thought to have been possibly damaged in an earlier grounding.
In any case, it is a very dramatic set of photos and I am really glad that all escaped without major injury.