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To convert from US Survey Foot (ft-us) to Fathom (fathom), use the following formula:
Fathom (fathom)
= 1.000002 × 16× US Survey Foot (ft-us)
= 0.166667× US Survey Foot (ft-us)
Let's convert 5 US Survey Foot (ft-us) to Fathom (fathom).
Using the formula:
5 × 0.166667 = 0.833335
Therefore, 5 US Survey Foot (ft-us) is equal to 0.833335 Fathom (fathom).
How many us survey feet are in one fathom? One Fathom (fathom) contains 5.999988000023999952 US Survey Feet (ft-us) — the inverse of the factor above. Multiplying by 0.166667 takes you from us survey feet to fathoms; multiplying by 5.999988000023999952 brings you back.
Put in words: one us survey foot equals 0.166667 fathoms, so the us survey foot is the smaller unit of this pair. Converting between them never changes the amount of length being measured — only the size of the unit you count it in.
The US Survey Foot is a unit of length historically used for land surveying in the United States.
It is very close in length to the international foot, equaling approximately 1.000002 international feet (ft). The plural form is US Survey Feet.
The origin of the US Survey Foot dates back to the Mendenhall Order of 1893. This order defined the relationship between the meter and US customary units.
It established that 1 meter is precisely equal to 39.37 inches. From this relationship, the US Survey Foot was derived, defined as 1200/3937 meters.
This definition differs slightly from the international foot, which was established in 1959 and is defined as exactly 0.3048 meters.
To simplify measurements and prevent confusion, the National Institute of Standards and Technology (NIST) and the National Geodetic Survey (NGS) made a critical change.
They officially retired the U.S. Survey Foot on December 31, 2022.
Surveying and mapping applications in the United States will now use the international foot. This critical change helps unify the National Spatial Reference System (NSRS) and prevents costly errors in large-scale projects.
While the difference between a US Survey Foot and an international foot is minuscule—only about two parts per million—it becomes significant over large distances.
For every mile, the discrepancy adds up to approximately 1/8 inch.
This minor error may not be significant for a backyard fence. However, for massive construction projects and infrastructure development, such as bridges that cross state lines, the accumulated error can lead to severe misalignments and costly mistakes.
A fathom is a unit of length in the imperial system of measurement.
It is most famously used for measuring the depth of water.
A fathom is equal to exactly 6 feet (or 1.8288 meters). The plural form is fathoms.
The word "fathom" originates from the Old English word "fæthm," which means "outstretched arms" or "a pair of embracing arms."
Historically, a fathom was defined as the distance from the middle fingertip of one hand to the middle fingertip of the other when a person's arms are fully extended.
This made it a convenient and readily available unit of measurement for sailors and workers.
The fathom is best known for its use in a nautical context to measure water depth.
Mariners would drop a weighted line, called a sounding line, into the water and count the number of "arm spans" it took to reach the bottom.
This measurement was crucial for safe navigation, anchoring, and creating nautical charts to map the seabed.
While modern technology and the metric system have replaced the fathom in official hydrographic surveys, its influence persists.
The term is still used informally in commercial fishing and can be found on many older nautical charts.
Figuratively, the verb "to fathom"—meaning to understand something deeply—is a direct link to the original act of measuring depth and getting to the bottom of things.
Here are some quick reference conversions from US Survey Foot (ft-us) to Fathom (fathom):
| US Survey Feet | Fathoms |
|---|---|
| 0.000001 ft-us | 1.66667× 10-7 fathom |
| 0.001 ft-us | 0.000166667 fathom |
| 0.1 ft-us | 0.0166667 fathom |
| 1 ft-us | 0.166667 fathom |
| 2 ft-us | 0.333334 fathom |
| 3 ft-us | 0.500001 fathom |
| 4 ft-us | 0.666668 fathom |
| 5 ft-us | 0.833335 fathom |
| 6 ft-us | 1.000002 fathom |
| 7 ft-us | 1.166669 fathom |
| 8 ft-us | 1.333336 fathom |
| 9 ft-us | 1.500003 fathom |
| 10 ft-us | 1.66667 fathom |
| 20 ft-us | 3.33334 fathom |
| 30 ft-us | 5.00001 fathom |
| 40 ft-us | 6.66668 fathom |
| 50 ft-us | 8.33335 fathom |
| 100 ft-us | 16.6667 fathom |
| 1000 ft-us | 166.667 fathom |
| 10000 ft-us | 1666.67 fathom |
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