Here’s my take:

If you take a board and split it into any amount of pieces, they’re all the same board, just in pieces.

If you take a board and put it somewhere else on the ship it’s the same board.

If you have two boards which were manufactured as they are now, (ie they were cut into their desired shape and considered complete boards), even if they’re the same size and from the same tree, they are different boards.

A board becomes its own distinct entity once cut from its source wood with intention to make a board and is considered complete (ready to use).