On Wed, 08 Sep 2010 16:54:52 -0500, Jim wrote:

I thought a derelict vessel was an abandoned vessel.
If there are folks living on a vessel - like a Wilbur Hubbard for
example - you might call that a vessel in need of TLC, or a decrepit
vessel, or a floating pile of crap.

Theoretically you are correct, a true derelict must be abandoned.
I've taken the liberty of expanding the definition slightly to include
totally unseaworthy vessels that are no longer capable of going
anywhere and have fallen into a very neglected state. In truth, most
vessels like that eventually become true derelicts even if someone is
living aboard them at the moment. As long as Wilbur's boat still has
a mast, rigging, sails and a working engine, it might still be
seaworthy. Who knows.