Dead water

Dead water

Dead water is the nautical term for a strange phenomenon which can occur when a layer of fresh or brackish water rests on top of denser salt water, without the two layers mixing. A ship powered by direct thrust under the waterline (such as a propeller), traveling in such conditions may be hard to maneuver or can even slow down almost to a standstill. Much of the energy from the ship's propeller only results in waves and turbulence between the two layers of water, leaving a ship capable of traveling at perhaps as little as 20% of its normal speed.[citation needed]

The phenomenon was first described by Fridtjof Nansen, the Norwegian Arctic explorer. Nansen wrote the following from his ship Fram in August 1893 in the Nordenskiöld Archipelago near the Taymyr Peninsula:

  • "When caught in dead water Fram appeared to be held back, as if by some mysterious force, and she did not always answer the helm. In calm weather, with a light cargo, Fram was capable of 6 to 7 knots [1]. When in dead water she was unable to make 1.5 knots [2]. We made loops in our course, turned sometimes right around, tried all sorts of antics to get clear of it, but to very little purpose."[citation needed]

This phenomenon is observable where glacier runoff flows into salt water without much mixing, such as in fjords.

See also

References

  1. ^ 6 to 7 knots (11.1 to 13.0 km/h; 6.9 to 8.1 mph)
  2. ^ 1.5 knots (2.8 km/h; 1.7 mph)

External links


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Look at other dictionaries:

  • Dead water — Dead Dead (d[e^]d), a. [OE. ded, dead, deed, AS. de[ a]d; akin to OS. d[=o]d, D. dood, G. todt, tot, Icel. dau[eth]r, Sw. & Dan. d[ o]d, Goth. daubs; prop. p. p. of an old verb meaning to die. See {Die}, and cf. {Death}.] 1. Deprived of life;… …   The Collaborative International Dictionary of English

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  • dead-water — deadˈ waˈter noun 1. Still water 2. Eddy water closing in behind a ship s stern • • • Main Entry: ↑dead …   Useful english dictionary

  • dead water — noun 1. : standing or still water 2. : slack water, neap tide 3. : the mass of eddying water formed along a ship s sides in her progress through the water …   Useful english dictionary

  • dead water — 1) unmoving water in a water body 2) the eddy water behind the stern of a boat …   Dictionary of ichthyology

  • dead water — /dɛd ˈwɔtə/ (say ded wawtuh) noun water which impedes the movement of a ship, comprising a layer of fresh or brackish water, as from a rapidly melting glacier, on top of a denser layer of salt water; the ship s propeller creates turbulence… …  

  • dead water — 1. water eddying beside a moving hull, esp. directly astern. 2. a part of a stream where there is a slack current. [1555 65] * * * …   Universalium

  • dead water — noun The eddying water under a slow moving ships counter …   Wiktionary

  • dead water —    Standing, stagnant water [16] …   Lexicon of Cave and Karst Terminology

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