Originally Posted by SloopJonB
I was thinking about the use of the buttock lines to cross check for hull fairness and balance.
Maybe.. but the hull lines are shown quite clearly on other plans I have, so this is for something else again.
Given that this was produced by a skilled draftsman in the days before CAD, I can't believe that:
(a) they did it for no other purpose than to fatten the drawing package,
(b) they made them up.
...so the questions remain...