The fathom is a measurement of length derived from the distance between outstretched arms. In our drying racks we supply 8 fathoms of cord, about 14m. A fathom is an eminently sensible measure for rope and cord, as that is how you lay it off a roll or coil of rope; the action and the measure all in one.
Body based scale interests me – as a child of the metric system (and thankful not to have to work in fractions of an inch) I was lost when shipbuilding where the dimensions where all imperial. I did come to find the inch and foot handy units to work with and got up to speed on the fractions eventually.
There is a human scale somehow embedded in the evolution of feet and inches, and still a whole generation who think in imperial… not to mention the entire US. Metric is more cerebral, although neat in the way a litre of water is a cubic decimetre is a kilo.
A fathom evokes its rich history, and of course the nautical spirit, where ropes and rigging once reined supreme, the high technology of its time. As a body reference (the width of your arms are your height) the fathom gives a measure easy to imagine.