Every diver needs to understand the tides that he is diving in. A tide is simply long, slow waves that move towards the shore from the ocean. These waves are generally created by the pull of the moon and sun on the earth. A high tide is basically when the highest point of a wave actually reaches the sea shore and the low tide is then the lowest part of it actually reaches the shore. When the waves are coming towards the shore, we call it the high tide and when they are moving away from the shore we call it the low tide.
These tides also cause water to flow in a horizontal direction. This causes tidal currents which tend to be at their strongest when both low and high tides are approaching. However, once the high tide or low tide has been reached, the current will generally be weaker as it turns and begins to go in the other direction. This is what is commonly referred to as a slack tide.
What Causes Them?
Tides are formed by a pull from both the sun and the moon. The sun tends to be larger and therefore has a stronger pull, however, the mood tends to be closer to the surface of the earth and therefore has a greater effect on the tide. As the water gets pulled up towards the moon, a bulge is created on that particular side. This causes high tide on that side while the side without a bulge has low tide. As the tides change so does the strength of the various tidal currents.
Different Kinds of Tides
Spring tide – This occurs when the earth, moon and sun are in a straight line. The moon and sun will generally be pulling in the same direction creating particularly low and high tides. This also leads to strong currents.
Neap tide – This one comes a week after the very high tides of the spring tide. The moon and sun tend to be at right angles and partially cancel each other out. The result is a moderate tide and tidal currents that are weaker.
Both Spring tide and Neap tied are experienced two times every month.
There are several other things that influence tides and currents including local weather patterns and wind, how inlets and bays are shaped and the shoreline as well. As a diver, you need to take all of these into consideration when planning your dive. If you want easy dive work with the neap tide but if you want swift drift diving, spring tide will work for you.