- 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 andlow tide , and occurs when the direction of the tidal current reverses. [http://eezway.org/clinic/Oceanography/Resources/Tides.pdf The American Practical Navigator, page 139] Commonly availabletide table s 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 atidal atlas or thetidal diamond information on anautical chart . [Sport Diving, British Sub Aqua Club, ISBN0091638313, page 167]For
diver s, 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 reducevisibility , as there is no current to remove debris such as sand or mud. Except whendrift diving , it is standard practice for divers to plan a dive at slack times.For
sailboat s 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.References
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