By Paul Smith Contents Tides Currents Wind Weather Tides Each 25 hour period is divided up into 4 tides approx 625 hours apart There are 2 high and 2 low tides within this period At ID: 422995
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Slide1
Sea Swimming Conditions
By Paul SmithSlide2
Contents
Tides
Currents
Wind
WeatherSlide3
Tides
Each 25 hour period is divided up into 4 tides (approx 6.25 hours apart).
There are 2 high and 2 low tides within this period
.
At
low tide the sea retreats and usually sand will appear
.
At high tide the sea will reach its furthest point up the beach (often marked by dried seaweed and small pieces of driftwood).
Tide TablesTables showing the tide times and the height of the tides can be picked up at surf shops, the marina and online (there is even an iphone app!). Slide4
12 Part Rule
During each tidal period (6.25 hours) the amount of sea water that moves can be divided into 12 equal amounts.
When
the tide begins to Flow or Ebb in the first hour, 1/12
th
of the tidal range will pass through, in the second hour a further 2/12
th
and in the third and fourth hour 3/12th, for the fifth & sixth hour the tidal range slows down to 2/12th’s and 1 /12th.
So you can calculate from this that the tide is at it’s strongest in the 3rd and 4th Hour (mid-tide).
TidesSlide5
The sea will retreat furthest and move up the beach furthest each
spring tide (when there is a full or new moon).
There will be least movement of the sea during a
neap tide
(usually about 7 days after a Spring tide).
Typically a spring tide will have a tidal range of up to 7 metres whereas as Neap could be as little as three Metres.
TidesSlide6
Currents
Current direction
When the tide goes out (ebbs) the current will move to the west.
When the tide comes in (floods) the current will move to the east.
Tide out
Tide inSlide7
How does this affect us as sea swimmers
Understanding
tides and currents is helpful - as swimming with the tide can sometimes make it about 50% faster/easier for us.
Swimming
against it can make it 50% slower/harder
.
For example it can take 20 minutes to swim with the current between the piers but if you swam the other way it could increase to 40 minutes
.During spring tides these currents can have even more power and are particularly strong mid tide.Slide8
Weather
Forecasting
Weather
It’s very important before going swimming to check the weather forecast (as well as the tide tables).
http://www.visitbrighton.com/site/tourist-information/tide-timetables
I find www.xcweather.co.uk very useful. It provides forecasts every three hours for the next five days (including wind direction, wind speed, temperature and whether it’s going to be sunny/cloudy/misty etc.Slide9
Wind
The wind is an important feature of sea swimming and in most cases creates waves.In Brighton winds are mostly from the south west (prevailing winds)
If a wind comes from the north you will have a flat sea!
Wind from the south produces a sea with waves.
Wind from the South or South West often produces the roughest seas (sometimes called swells)
If you plan your swims to catch the tide and you have the wind behind you it will increase your speed significantly.Slide10
Wind
Measuring
wind speed
The Beaufort Wind Force Scale
measures wind speed between Force 0 – 12.
0 is a completely flat mirror like sea with almost no wind.
12 is a completely white sea with driving spray and very poor visibility. Wind speed would be above 70 miles per hour. Wave height on the beach would be well in excess of 3 metres (and considerably higher out at sea)
http://en.wikipedia.org/wiki/Beaufort_scale
Slide11
WindSlide12
WindSlide13
WindSlide14
THE END