Nothing wrong with the boat
After many expert reviews, it has been determined that a single wave or a series of waves sunk my Larson Cabrio 29'. No drain tubes disconnected, both aft and mid bilges operating. Anchoring off the back, even on a nice day is a Bad idea and on lake Erie you are still are subject to other boat wakes.
There was a real current that day.
I will have a windlass and will not be anchoring off the back in any boat with a walk through stern door. Mine has a gap under it also, but believe me I have looked a lot of boats in the last month and there are a lot like mine including sea rays.
Hope everyone learns from my mistake and saves themselves an uncomfortable and expensive lesson. Thank God I didn't have some of my older friends out in late October.
Jeff