I own a copy of the thirteenth edition. Kind of remarkable, that. Given the choice of the book, or a complete collection of Aubrey/ Maturin for that proverbial desert isle, well, travel light I would advise.
The Campbell plans are bound into the book at locations in the text that sort of make sense. Neatly folded, with a corner turned back. I suppose the positive to that approach is that they are hard to lose, but also harder to copy. And I haven't discerned the scale, though it is thoughtfully a "graphic" one, easily determined and enlarged/ reduced.
I bought the book in excellent condition for about $ 20.00, used.
That said, three of the four photos you show are not of Campbell plans, at least not from the book. Only the longitudinal section is a drawing from the book, and even that differs a little in format- the book drawing having an adze rendered to the left of the block of specifications. Maybe I can't see it in your picture.
The other three are rendered in a different style, by a hand that appears different, and the lettering style is quite different. My implied caveats are only because I cannot see the whole drawing, and next I'll hear "No Bill, you are wrong, there's a signature "GFC" in the corner", but I would guess these drawings are from another source. The fact that they are listed as sourced from the book makes me think so too. Maybe you have something there more valuable than a book that's been through thirteen printings by 1995?