I'm not questioning these guys' credentials as archaeologists, but the statement "-In the very first dives to the wreck, divers returned a ship's bell dated 1709. This proves the wreck can't be any older than that date. " doesn't make sense. Is there any reason to think that, if the ship lost its original bell (for whatever reason), that the new bell wouldn't have a different date?
The WRECK cannot be older that the bell, not the SHIP
I think its just confusing writing. I believe what they mean by 'wreck' is that the ship itself no matter how old could not have 'sunk' earlier than the year the bell was manufactured-1709.
The date of the shipwreck, not the date the ship was built.
It's not like treasure hunters haven't been known to 'salt' a wreck with a few choice pieces in order to 'prove' their conclusions about a wreck.