An intro to ocean tides
There is nothing like watching the rise and fall of the tides on a beach. They are a beautiful example of the connections between the land and the sea (and us too as observers!)
So what causes the tides and why is it important to know about them when planning your next visit to the beach? Let’s dive in.
What causes tidal movements?
Here in our southern sea’s we have two high and two low tides in a 24 hour cycle (usually, but this can vary depending on the location).
The gravitational pull of the moon and sun causes tidal movements in the oceans. The moon has a stronger influence/pull than the sun because the moon is much closer to the Earth than the sun is (fun fact do you know there is terrestrial tides too?)
The moon creates a ‘bulge’ when the planet’s water is pulled towards the closest side of the moon - this creates the high tide. It also creates a bulge on the other side of the planet too. Between these two bulges is the low tide.
When the sun, moon, and earth are in alignment (at the time of the new or full moon), the solar tide has an additive effect on the lunar tide, creating extra-high high tides, and very shallow low tides, both commonly called spring tides.
The flow of water from high tide to low tide is called an ebb tide, and a flood tide from low to high.
Why is is important to know what the tide is doing?
For many reasons, including when to plan a surf, beach walk, snorkel, dive or swim, as the tides can effect how much beach there is, to what size and power the waves have. Rip currents too can behave differently pending if the tide is coming in or going out.
Check out the below table which gives some pointers on how the different tides affects conditions and your safety.
Generally speaking, the waves are more dumpy with stronger rips when the tide is heading out towards low tide. An incoming tide as it reaches high tide is usually safer for swimming with faster waves.
Source: Public Safety and Aquatic Rescue Manual
What tides are best for getting in the ocean safely?
Some beaches you will notice dramatic changes in the tidal difference, others not much at all. It is quite common on many beaches along the Surf Coast to have not beach left at high tide to walk on! Low tide is often a great time for surfing point breaks, exploring rockpool and walking along the beach to see what’s washed up.
Rising to high tide is generally safer for rips, waves and surf but this can vary from beach to beach. It is good to get to know your local beach well. Next time you’re out visiting take note of where the tide is at during its cycle and note the conditions.
Lorne Point.
