Convert Nautical Mile (UK) (NM (UK)) to Fathom (US Survey) (fath (US)) instantly.
About these units
Nautical Mile (UK) (NM (UK))
The UK nautical mile was historically defined as 6,080 feet, slightly longer than the international nautical mile (1,852 meters). Before international standardization in 1929, British charts and maritime documents relied on this definition. It approximated one minute of latitude but used British feet rather than an exact metric conversion. Although the UK adopted the international nautical mile long ago, many older navigation charts, historical records, and maritime traditions still reference the UK version. Researchers dealing with archival naval documents must carefully distinguish between the two definitions to avoid errors in distance or speed calculations. The UK nautical mile is a reminder of the era before global standardization when each nation maintained its own measurement conventions—even for activities as universally critical as seafaring.
Fathom (US Survey) (fath (US))
The US Survey Fathom is defined as 6 US Survey Feet (~1.8288 meters), identical in proportion to the traditional fathom but scaled to the US Survey Foot. Maritime surveys, early river navigation, and hydrographic measurements relied on this unit for determining depths and plotting charts. In terrestrial applications, the fathom occasionally served as a practical measure for large structures or obstacles. Although less relevant in contemporary usage, understanding the US survey fathom is crucial for interpreting historical navigation data, nautical charts, and engineering projects using older measurement systems.