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.
"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."
Exactly, it is called "terminus post quem" dating.
In archaeological theory it means that a given loci (archaeological layer or feature [in this case a shipwreck}) can only date to or after the most recently dated in situ artifact.
For example, if there are coins found on the ship that have a date of 1740 then the wreck would have to date from 1740 or after since the coin did not exist prior to that date.