Slack water

Slack water

Slack water, or slack tide, is the period during which no appreciable tidal current flows in a body of water.

Slack water usually happens near high tide and low tide, and occurs when the direction of the tidal current reverses. [ The American Practical Navigator, page 139] Commonly available tide tables indicate the time of high and low water at popular locations, such as ports, but not at every specific area that a navigator may be. Slack water can be accurately calculated in most regions using a tide table or current table combined with either a tidal atlas or the tidal diamond information on a nautical chart. [Sport Diving, British Sub Aqua Club, ISBN0091638313, page 167]

For divers, the absence of a current means that less effort is required to swim to and remain at a given site, and there is less likelihood of drifting away from a vessel or shore. Slack water can reduce visibility, as there is no current to remove debris such as sand or mud. Except when drift diving, it is standard practice for divers to plan a dive at slack times.

For sailboats with limited top speeds, a favourable current can substantially improve the vessel's speed in the water. Difficult channels are also more safely navigated during slack water, as current may set a vessel out of a channel and into dangerous shoal water.


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Look at other dictionaries:

  • Slack water — Slack Slack, a. [Compar. {Slacker}; superl. {Slackest}.] [OE. slak, AS. sleac; akin to OS. slak, OHG. slah, Prov. G. schlack, Icel. slakr, Sw. slak; cf. Skr. s[.r]j to let loose, to throw. Cf. {Slake}.] Lax; not tense; not hard drawn; not firmly… …   The Collaborative International Dictionary of English

  • slack water — n. 1. the period between tides when the water is neither in ebb nor flood 2. any stretch of water having little or no current …   English World dictionary

  • slack-water — I. ˈ ̷ ̷| ̷ ̷ ̷ ̷ adjective Etymology: slack water 1. : marked by slack water a slack water period 2. : carried on in slack water produced artificially (as by a lock or dam) slack water navigation II …   Useful english dictionary

  • slack water — slack′ wa′ter n. 1) oce a period when a body of water is between tides 2) oce water that is free of currents • Etymology: 1760–70 …   From formal English to slang

  • slack water — noun 1. a stretch of water without current or movement suddenly they were in a slack and the water was motionless • Syn: ↑slack • Derivationally related forms: ↑slack (for: ↑slack) • Hypernyms …   Useful english dictionary

  • slack water — noun Date: 1764 the period at the turn of the tide when there is little or no horizontal motion of tidal water called also slack tide …   New Collegiate Dictionary

  • slack water — 1) the period at high or low tide when there is no visible flow of water 2) an area in a sea or river unaffected by currents; still water …   Dictionary of ichthyology

  • slack water — 1. a period when a body of water is between tides. 2. water that is free of currents. [1760 70] * * * …   Universalium

  • slack water — still water; water between high and low tide …   English contemporary dictionary

  • slack water — /slæk ˈwɔtə/ (say slak wawtuh) noun the period of still water between tides …   Australian-English dictionary

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