When we determine the diameter of a rope, it is possible to have two different measurements because of the twisted or braided construction. The greater is used to define the actual size of that line. The three rope calipers shown are from three different Canadian rope makers. Manufacturers and resellers frequently gave out these calipers to valued customers. Produced by specialist rule makers and branded for each distributor, the calipers made it easy to check the size of a rope and also gave the basic standards for the sizes available. In this case the units are stamped with tables for manila rope. All three tools show that a 1" diameter rope has a circumference of 3" with an estimated breaking strength of 9000 to 9200 pounds. Each manufacturer had its own interpretation of the length required for one pound of manila rope in the 1" size.

D.S. Orr

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