The Mariana Trench

The Mariana Trench - Converting to Nautical Measurements

The Mariana Trench is 6033.5 fathoms deep.  Knowing that it is (11,033 meters (36,201 feet) deep,
how do do we perform the conversion to fathoms?  Convert feet to fathoms and other nautical measurement units with this table from the US Naval Oceanographer.

Conversion Table

1 fathom = 6 feet
100 fathoms = 1 cable length
10 cables length = 1 nautical mile
1 nautical mile = 1.151 statute miles (length of a minute of longitude at equator)
3 nautical miles = 1 league
1 knot = 1 nautical mile per hour = 1.151 statute miles per hour
10 chains = 1 furlong = 201.17 meters
60 nautical miles = 1 degree of a great circle of earth (latitude)
1 statute mile = 5280 feet
1 nautical mile = 6076.115 feet

Note: Statute miles is what we know as miles and is a measurement of distance over land. Nautical miles is a measurement over water.

Origin of Nautical Terms

Fathom - Sailors use to throw a line into the water, wait until it hit the bottom, pull it back up, while measuring the length of the line from finger tip to finger tip. The arm span of an average sailor was 6 feet and called a fathom.

Knot - Lines used to be thrown over the sides of ships to determine speed. Each line was divided into 47 ft. 3 in. sections and were called knots. The line was allowed to run over the ship's side while a 28-second glass was emptying itself. The length of the knot was derived from the proportion that one hour (3600 sec) is to 28 seconds as one mile (6076.115 ft.) is to the length of one knot (47 ft. 3 in.)

The information on this page is based on public domain text from US Naval Oceanographer:

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