Ha!! My father must have been rich ..lol.... because he always had one of these folded 'rules'... in fact he had several , like these...
Actually ''all hands on deck means ..''all watches to be on deck at the same time''.... Holly Saunders ex naval wife..
Okay, one more using string, yarn and cloth. A yard at the millinery store was from the elbow to the tip of the middle finger. Most people accepted that but the more suspicious people raised a little Cain so someone came up with placing two tacks on a table with the distance between the tacks as one yard. Hence the statement: "getting down to brass tacks".
I think that this has been an accepted way of measurement for many years now. We measure our height in "feet" and we measure a horse's height in "hands". Something can be an "arm's length" away from us, or it can be a "hair-breadth " away. In order to determine this, we "eye" it. Race horses can win by a "nose", and when we are in trouble, we are "in water up to our neck". There are probably lots more ways we use body parts as a reference; but I am going to just stop right here, so I can "toe the line".
The navy is indeed very strange. A nautical mile isn't the same as a land mile, instead of a 60 minute clock they have a hundred minute clock, 8 bells isn't 8 o'clock and speed is measured in knots. There are good reasons behind all of them but I'll leave that up to the Navy folks here.