There was a discussion similar to the above post in WoodenBoat Magazine a few years ago. An "original" vessel need not have even one original piece it she has been continually maintained and retains reasonably true to the original plan. There is a vessel in Delaware Bay which was abandoned in a creek for many years. When dug out, only two small pieces of wood were found to be usable. She is considered a restoration, rather than a replica and sails as NJ's official tall ship.