Either 1 or more of the following happened:
1. The board slide down to far in the trunk (best case and most likely)
2. You ran over something (doesnt look like that happened)
3. The trunk/hull failed under the stress of sailing on a windy day (worst case)

It looks like the board slid down to far and the loads on the daggerboard increased and the trunk didnt have enough structure to hold the top of the board in the middle of the trunk, and it sheared off the trunk and then the second crack was the bottom part of the trunk tearing away from the hull.

Or you ran over something, which pulled the board aft, and the trunk sheared in the middle and then delaminated off the hull. I doubt this happened because the top of the trunk would most likely be damaged as well, and the board would be banged up too. Most of the time when you run over something the board takes most of the abuse, followed by the trailing edge of the trunk/hull. The impact usually james the trailing edge of the board backwards into the hull like a knife. It doesnt look like that happened.

I'm betting the board slide down to far, you didnt notice it and the loads from the board being to deep sheared off the bottom of the trunk.


If thats the case its good news, just glue it all back together and make sure the board cant fall below the deck in the trunk.

If the board didnt slide down into the trunk, and you didnt run over something, I would be really worried. If thats the case it means the trunk failed under normal sailing conditions. Thats a pretty serious design/build issue.