Hi Brian,
Am I correct in understanding that your boat is in a tidal area and lies on its hull when the tide is out?
I looked up this post (dutch) but if you hit the translate button it should work.
@Rob_Listo should be able to clarify his post too.
Hope this is a starting point. In order to have a good look at what has happened you need to hoist the boat up I guess. Could be that the keelhead came off the keel itself and that is causing the jam. It is a known weak spot.
Koen