Sailor Speak of the Week – Fathom



  • A unit of measurement equal to six feet.


From Anglo-Saxon word foethm, meaning the length of one’s fully extended arms as well as to embrace. Entered into English in the 12th century as fadme. Took on its modern form in the 16th century.


Often used in reference to water depth or lengths of line or chain. Soundings would be taken to measure the depth of the water with the use of a sounding line. A sounding line is rope with a lead weight attached to one end and knots or marks spaced at six feet intervals. The weighted end is tossed overboard and the “leadsman” counts the number of knots or marks to measure the depth of the water. Usually reported as “(a number) fathoms”. For example, 12 fathoms = 72 feet.

Also related is the term “deep six” which is slang for throwing something overboard. An indication that the water is six fathoms deep.

For the amusement of the old salts, newcomers aboard the ship may be sent on snipe hunts for non-existent items. For example, “I need 6 fathoms of Plimsoll line!” (Note: Plimsoll lines are markings on the hull of the vessel at the waterline to indicate draft…they’re not measured in fathoms!)


Angelucci, E. & Cucari, A. (1975). Ships. Milan, IT: Arnoldo Mondadori Editore.

Rogers, J.G. (1985). Origins of Sea Terms. Mystic, CT: Mystic Seaport Museum.

Theberge, A.E. (1989). Sounding Pole to Sea Beam. Retrieved from

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