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Measuring line by circumference


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If this has been asked before, I apologize. Just point me to the correct thread.


I'm curious-when I look at rigging tables in Steel and Lever and other old texts, rigging size is always shown in circumference, whereas all the work we do (and most modern rigging that I'm aware of) is shown in diameter.


So, why did they measure line size that way? I'm trying to come up with an advantage for measuring circumfrence over diameter, and I keep drawing a blank.


Any thoughts?





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Lack of math skills - anyone could measure the circumference, but you needed to convert that to get the diameter.


Most sailors and shipyard workers had little or no arithmetic - which is also why there is generally a rather large section on math is the early books on shipbuilding and naval architecture.


Neither should a ship rely on one small anchor, nor should life rest on a single hope.

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Don't have a clue but it is kind of traditional today, tradition always has a reason that may have been lost or not really the best way to do it today. I would guess that circumference was easier to measure while determining the strands need to meet specifications at the rope walk. Squeeze a bunch of threads onto a round bundle, pass a line around it and mark it, then removing that line and measuring it would provide a more uniform and repeatable measure than attempting to measure a bundle of threads with calipers. May have nothing to do with it but you asked for thoughts.


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It is simply easier to measure the circumference: Just take a piece of rope and wrap around. For the diameter you need a tool like a caliper.



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