Why did the Mary Rose sink?
Nobody knows for sure, but some of the theories are listed here:
Did the Mary Rose sink on her Maiden Voyage?
No. The Mary Rose had a 34 year long career before sinking.
You can find out more here:
Who found the Mary Rose?
The modern search for the Mary Rose began in 1965, lead by Alexander McKee, a diver and historian. The first timbers were discovered by Percy Ackland, a member of McKee's team, in October 1971.
I was on the beach and found a timber. Is it from the Mary Rose?
Probably not. The wreck site is covered up, so no timbers would have moved by the tides.