Embedded Files
Ocean currents and tidal currents.
Ocean currents are caused by long slow moving waves that build up speed and power as the travel across long ocean distances. Consider ripples over the distance of a bathtub, for an immediate comparison. The current can change in speed and power depending on other environmental effects such as ocean depth, wind speed and even the tidal current for examples. Tidal currents while created by ocean currents, mostly effect the environment at or near the shoreline. This is the tidal pattern that is referred to when considering the effects of the lunar cycle on the High Water / Low Water and is what is predicted on a daily basis. Tidal currents caused by … Tidal currents are caused by the tides hitting the shore, creating a current layer of flood over-top of the ebbing water that has just previously crashed the shore.
Tide feature definitions.
Tidal Race; When the ebb or flood of a tide is forced / bottlenecked through a small area.
Tidal Overfall; Areas in which tide changes direction.
Whirlpools; Areas of rotating water on a fixed point.
Waves; Fast land bound water flowing over draining sea-bound water.
Rip Current; Fast moving swells of water moving directly away from shore.
Currents immediate effects on kayaking.
Changing speed and direction of water flow
Changes / creates water features (Rapids, Channels, Waves, Eddies)
Dictates your itinerary and plan.
Critical Tidal Terminology
Spring Tide - The spring tide happens on the full moon, and it is when the swells, currents and tides are at their highest. With the highest volume of water, this creates potentially the most dynamic tidal patters, barring major environmental events.
Neap Tide - The neap tide is the opposite, happening when the moon is formed at a right angle from the sun. This event comes with the lowest tides and currents of the lunar cycle with the least volume of water.
Ebb - The ebb is the tidal state in which the direction of current is back out to sea, moving out to low tide.
Flood - The flood is the tidal state in which the direction of current is inland, going into high tide.
Diurnal - “An area has a diurnal tidal cycle if it experiences one high and one low tide every lunar day.” (noaa)
Semi Diurnal - “An area has a semidiurnal tidal cycle if it experiences two high and two low tides of approximately equal size every lunar day.” (noaa)
Tidal Day - The time between the two consecutive high waters.
Tidal Month - The time between Spring (or neap) Tides.
Tidal Year - Another term for a full Lunar year.
Tidal range - The tidal range is the water height difference between high and low tide.
Rule of 12ths
Hour 1 – Hour 2 – Hour 3 – Hour 4 – Hour 5 – Hour 6
1/12 – 2/12 – 3/12 – 3/12 – 2/12 – 1/12
Example.
(i) The total increase, rise or range in water level between low and high tide is 14 - 2 = 12 metres.
(ii) In the first hour, the water level would rise by 1 twelfth of the total (12 metres) or: 1 metre.
In the second hour, the water level would rise by 2 twelfths of the total (12 metres) or: 2 metres.
(iv) In the third hour, the water level would rise by 3 twelfths of the total (12 metres) or: 3 metres.
50/90 Rule
Using the Tidal 6 Hour Cycle,
Hour 1 – 50%, Hour 2 – 90%, Hour 3 – 100%, Hour 4 – 90%, Hour 5 – 50%, Hour 6 – 0%.
This is with the potential maximum of the current, usually used as a very rough estimate for how fast the flow is moving in any given area. Is useful for identifying the best times of day to be crossing through areas of high flow. The percentage of the maximum current speed as shown by tidal information.
Page updated
Google Sites
Report abuse