Slow salute to the survey foot

“Ensign Virginia McKachern studies a chart in the Port Director’s Office, Jacksonville, Florida, to which she is now attached. Hydrographic distribution has become a function of this office, photograph released circa 1943.” U.S. Navy photograph, now in the collections of the National Archives. 80-CF-8811-7_Box 175

On New Year’s Eve 2022, the National Institute of Standards and Technology and National Geodetic Survey, National Ocean Service, NOAA, and the Department of Commerce officially retired the U.S. survey foot, established in 1893, and replaced it with the international foot.

For reference, A U.S. survey foot is expressed as a fraction — 1200/3937 meters — while an international foot is expressed as a decimal, exactly 0.3048 meters. The U.S. has been in a slow march for the past two years to halt the institutional use of the “old” foot. Meanwhile, the U.S. military has largely been metric since 1957, as a part of NATO standardization, although some things (altitude and ship dimensions) are kept in feet for traditional reasons.  

As noted by NOAA, “Doing so will reduce surveying errors that can cost money, and increase accurate positioning for surveying, mapping, and more.”

As detailed by NIST:

Beginning on January 1, 2023, the U.S. survey foot should be avoided, except for historic and legacy applications and has been superseded by the international foot definition (i.e., 1 foot = 0.3048 meter exactly) in all applications. Prior to this date, except for the mile and square mile, the cable’s length, chain, fathom, furlong, league, link, rod, pole, perch, acre, and acre-foot were previously only defined in terms of the U.S. survey foot.

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