This excerpt from our latest book, “From Truths to Tools,” speaks to a rather esoteric, but highly useful, rule for use with scaled drawings:
Here’s a typical, traditionally drawn small boat plan:
To find the dimension of any particular part of the boat, we simply set the divider to the part – here the cap on the centerboard trunk:
Then we transfer the dimension (what the Greeks called, more precisely, a “magnitude”) to the graphic rule…
…and read the numerical distance of 3′, 6″. This technique eliminates the need for an awkward and hard-to-read scaled ruler and, furthermore, works no matter what scale the drawing is made to.
— Jim Tolpin, byhandandeye.com