Trust me, metrology is my job. I know all there is to know about this kind of measurement.
To take a plane measurement on a mast and transfer it to a plane 3 decks below when you cannot use a gravity reference frame as the ship pitches and rolls in the water is a very cumbersome task. Almost 3 days of work, and difficult to put a number on the final accuracy.
Not interested in something they use in residential construction in Amsterdam. Please direct the response to the question asked.