The sun is shining and you're reading to jump in the water for a surf, but have you checked the tides at your local break?
Different surf breaks all have specific conditions depending on the tide, which will impact on the quality of the waves.
Here we aim to break down the types of tides, how they work and why they are important for your next surf.
What are Tides?
The gravitational pull from the moon and sun influence the movement of water on our beaches. This causes the rise and the fall of sea levels also known as High and Low tides.
The moon orbiting the earth and the earth orbiting the sun causes tidal bulges which, depending on their alignment, create tidal variations known as Spring Tides and Neap Tides.
High Tide
When the water reaches its highest point on the beach, this is known as High Tide.
Low Tide
Similiarly, the state of the tide at its lowest level is known as Low tide.
Slack tide
30 minutes before high or low tide, until 30 minutes after, there is a period of relative calm water. This is known as Slack tide and usually affects the frequency and size of swell.
Spring Tides
Once a month, when the moon is between the earth and the sun and is not visible to the naked eye, a New Moon appears.
A Full Moon is when the moon is opposite the sun and its sunlit side is completely visible. This also happens once a month following the moons orbit of the earth.
These alignments create a gravitational pull of both the moon and the sun which causes the oceans to ‘bulge’ more than usual. This is known as a Spring Tide and means that high tides are a little higher and low tides are lower than average.
Neap Tides
Seven days after a spring tide occurs, both the sun and the moon are at right angles to each other and are visible as a ‘half full’ moon. This cancels out the ‘bulge’ of the ocean and produces moderate tides known as Neap Tides. This means that high tides are a little lower and low tides are a little higher than average.
Rule of Twelfths
To determine the height of the tide at any time of the day, there is a calculation called the rule of twelfths. If you know the high and low tide heights, you can divide by twelve to work out the current height of the tide.
Water levels rise by 1/12th of the total tidal range during the first hour. In the second hour, it rises by an another 2/12ths of the total. During the third and fourth hour, it rises by 3/12ths and the increase slows down. In the fifth hour, the water only rises by 2/12ths, and in the sixth hour it rises by 1/12th. The sequence goes 1,2,3,3,2,1.
What does this mean for a surfer?
As well as a favoured swell and wind direction, every beach has its preferred tides and knowing how the tides affect the quality and size of surf can make a difference to your surf session.
You can purchase tide timetables at local surf shops or post offices near the coast or visit websites such as MagicSeaweed for more detailed forecast information.
Chatting to the local beach lifeguards or Surf School can give you a little local knowledge, so when the swells roll in, you’re ready to take advantage of the best times to hit the surf.
