It’s a common misconception that some areas of the world are tidal and some are not. In fact, if you take a look upon any of our location guides you will come across a section in which we state “Tidal? Yes/No”. So, what are Tides and how do they affect Kitesurfing?
The simple fact of the matter is that all areas of the world are tidal. Some are more tidal than others while some tidal differences are unnoticeable to the human eye and do not affect kiting at a location.
As kitesurfers, tides can affect us a lot. If we kite in an area unaffected by tides, then we can go about or kiting with the wind as sole concern. This changes as we move to tidal locations. In a location that has great tidal differences, we need to know how to work with tides to stay safe and get the most time and enjoyment from the conditions. We must be aware of how tides happen, how they affect us, and how to find information about local tides.
WHY DO WE GET TIDES?
High tides and low tides are caused by the gravitational pull of the moon. Despite the moons comparatively small mass, it is close enough to earth that it has enough gravity to pull on the water in the oceans; this is known as tidal force.
Tidal force causes water on earth to ‘bulge’ out on the side closest to the moon and the side farthest from the moon. These ‘bulges’ of water are what we know as high tide. The result is that the water lifts over the terrestrial surface on the two diametrically opposite sides of the planet. In the areas where water hasn’t bulged, water levels are then lower, which we know as low tide.
As the earth rotates 1 full rotation in 24hrs, each region of the earth will pass through each ‘bulge’. This is why we get 2 full tides (High, Low, High, Low) every day as your global position passes in and out of each ‘bulge’.
WHY AREN'T TIDES THE SAME EVERYWHERE?
Our explanation of tides has so far neglected the effect of land masses on water movement. The earth isn’t a ball covered with an even layer of water, there are seven continents with land that can block or slow water movement. This is why the difference between high and low tide in some places is unnoticeable and in other locations the difference is significant.
The effect of land masses is so significant that it can affect the tidal pattern. In most locations we have a Semi-diurnal tide (2 highs and 2 lows of around the same height). Land masses can affect tides so that they do not follow a diurnal pattern. There are places that have mixed semi-diurnal (varying tide heights pattern) or only a Diurnal tide (1 high and 1 low tide in 24hrs).
WHAT ARE SPRING AND NEAP TIDES?
How the sun and the moon align with the earth affects the tidal state on earth. When the earth, moon and sun line up, lunar and solar tides support each other, and the tidal effect is more extreme. These are called Spring tides, and they have a greater difference between high and low tide. We see full or new moon about every two weeks, and this is also how often we receive spring tides.
When the sun and moon are not lined up with the earth, solar and lunar tides oppose each other and the result is smaller tides. These are called Neap tides and are most noticeable on the half moon. They have a smaller difference between high and low tides.
As we know the phases of the moon, tide charts can be predicted years in advance.
WHAT ELSE AFFECTS TIDES?
Beyond gravitational forces, our planets weather systems can affect tides. Strong winds can push water onshore or offshore to slightly increase or reduce the tidal water movement outside of predictions.
High and Low-pressure systems can also affect tides. A very low-pressure system such as one brought about by a hurricane can cause tides that are far greater than predicted. High pressure can create lower tides than predicted as 1mb of pressure reduces tide height by approximately 1cm.
WHERE CAN I FIND TIDE MEASUREMENTS?
A quick online search for tide charts will provide all the information you need. Websites such as tide-forecast.com will provide measurements for tidal range and the time of high and low tide for many locations around the world.
Choose a tide chart closest to your location for most accurate results. The further your kite spot is away from the reference point the less accurate the data will be.
HOW TIDES AFFECT KITESURFING
Knowing when high and low tides occur and how large or small they will be is essential as it can affect when you can have your session.
In some locations, high tides will cover your launching and landing zone and place you too close to hazards. On low tides, other hazards such as reef may become exposed which make the location unsuitable for riding.
It is important to know whether you are on or approaching spring or neap tides. Spring tides result in more water movement and may shorten your kiting time as the high and low tides are at greater extremes. On a neap tide there will be less tidal movement, and so there will be less effect on your session.
Knowing how water movement occurs at your spot is essential as water movement may affect your upwind riding ability. It can also affect ability to retrieve your board should you become separated from it.
HOW CAN I WORK OUT WHICH TIME OF THE TIDE IS BEST TO GO KITESURFING?
Thanks to the rule of twelfths it is possible to estimate the height of the tide during any given tidal state. If you were to sit and watch the tide rise and fall you would see that in the first hours of a tidal shift the tide does not rise/fall very much. The entire process accelerates through the mid hours of the tide. The rate of flow in a tide increases to its greatest speed halfway between high and low tide. It then slows again towards the end of the tidal phase. This pattern repeats through each tidal movement.
The Rule of Twelfths applies to a normal semi-diurnal tide – a tide having two high waters and two low waters during a tidal day, which is exactly what happens in most locations.
With this, we can now find a safe time to kitesurf at locations which are limited by hazards at either high or low tide. We know that at a location with high tide hazards, we may have to wait a few hours for the tide to drop enough for safe kiting. We also know that with the greatest tidal movement around the mid point of any tidal phase, we can expect a stronger affect of water movement on our board. This could be a positive effect with wind against tide where upwind ability improves as the water movement makes it easier to ride upwind.
Remember to check your tides and know how the locations you kite at are affected by tides. Always ask the local kiters or school if you are unfamiliar with a kite spot.