Judge, obviously you're correct. Not every obstruction is on the charts. That cruise liner hit an uncharted rock off the Jersey coast that time.
Plus, there's floating debris. Down in the Keys right now there are docks and trees floating around. My friend once hit a couch taking his boat out of Port Canaveral. It happens.
However, I'm still guessing some level of operator error here.
- This was a heavily traveled area, not open ocean or a remote spot. The chances of an unmarked obstruction are slim.
- While not completely avoidable, floating debris is spotted by alert sailors.
- At sailboat speeds, what could you hit that would sink the boat? Maybe their refurbishment was not well done being amateurs.