I read a theory somewhere, maybe here on FR, that she was so heavily loaded and roller coasting up and down those big 25 foot waves that her bow hit the bottom and it broke her spine.
That theory seemed logical to me considering she is broken in half.
The waves were 25 to 30 feet but the troughs were also 25 to 30 feet. Making the actual wave height 50 to 60 feet
I read theories about Fitz being taken down by the 3 sisters, three big waves one right after the other, then the bow slammed into the lake bed, and she cracked up. The captain reported they were listing, so, probably taking on water at the time too. That last wave just swamped the ship. You would think there would be a lot of damage to the bow because of all of that weight from carrying ore.