Chain
Chain turns up in 2 fields: maritime, surveying. Here is what it means to the people in each one.
Chain in maritime
A heavy series of metal links used to secure anchors or handle massive loads.
A chain consists of interlocking steel links designed to bear extreme tension and resist chafing. In seafaring, it is primarily used as anchor rode, where its immense weight creates a catenary curve that absorbs shock loads and helps the anchor dig into the seabed. Ship anchor chains are sized by the diameter of the link metal and often feature a central stud in each link to prevent kinking.
"Pay out another shot of chain so the anchor holds in this blow."
Chain in surveying
A traditional measuring instrument made of wire links, or the unit of length equal to 66 feet.
A physical measuring device consisting of heavy wire links, traditionally used to measure horizontal distances in the field. The standard Gunter's chain contains 100 links and measures exactly 66 feet, a length that makes area calculations in acres mathematically simple. Although steel tapes and electronic distance measurement have replaced the physical tool, surveyors still use the word to describe measuring a distance or referring to the 66-foot unit in historical deeds.
"The old deed calls for a distance of five chains and twenty links along the stone wall."