Surfing is a great sport, but you can not surf unless you understand the science behind waves. Every wave is different but they all have similar origins and life cycles. In its purest form, an ocean wave is simply a wall of energy. This energy comes from wind blowing across the water. The amount of energy transferred to an ocean wave depends on the strength of the wind, the duration of the wind gusts over the water, and the fetch of the wind gusts (how far the wind blows over the water). A wave will have maximum energy if a wind gust is very strong, blows for a long period of time, over a large area of water. The farther away from the shore these waves are, the better the waves are when they reach the beach. This allows them to grow stronger and to spread out. This increases wave period, which is the time between successive wave peaks. Wave period is key to the quality of waves.
Wave period distinguishes between ground swells and wind swells, the two major types of waves. Wind swell is categorized by swells with a wave period less than fourteen seconds. These waves are generated by storm systems very close to the shore. Wind swell waves are generally the least favorable type of waves for surfers. They are small, usually very choppy, and are not conducive for surfing. Wind swells are characteristic of the majority of waves on the East Coast of the United States in the summer.
Ground swells are categorized by swell periods greater than 14 seconds. These waves are generally generate very far away from the beach by large storm systems. Waves in ground swells are much cleaner, larger, and very favorable for surfing.
Now that we understand what the basics of waves are, we have to understand what makes them good when they break at the beach. Every beach is different but typically, a wave has to have the proper direction and a long swell period. Also weather conditions at the break have to be conducive for wave riding. The factors that come into play here are local wind direction, tides, and local bathymetry. Before the waves even reach the beach, they have to have the correct direction to actually break at that beach. For example, the major surf spot in Hawaii known as the Banzai Pipeline, requires a northwest swell direction to break properly. Without this, the waves are focused to other beaches, meaning the waves will be better at other places. The correct swell direction is closely related with the period of the swell and the local bathymetry of the ocean. The longer the swell period is, the more energy a wave has. This energy extends way down under the surface of the water. As the waves approach the beach this energy is able to interact with the ocean floor near the beach. The characteristics of the ocean floor first directs the wave where it is going to go, and then dictates the waves shape and size. Going back to Pipeline in Hawaii, the ocean floor there has a very sharp increase right before the break. This results in Pipeline’s massive size and power. Beaches on the East Coast have a much more gradual buildup to the beach, so they are much weaker and smaller. Once a wave reaches the break, there are two factors that will affect it. These factors are tides and local wind direction. The wind has to be going opposite the direction of the waves. This provides drag for the wave so it breaks with a very hollow tube, instead of just collapsing on itself. Tides affect each break differently, but going back to Pipeline, if it is high tide, there is too much water on the reef for the wave to break. At low tide, there is not enough water on the reef and the wave breaks directly on to the reef. (On a side note, if anyone is a Jack Johnson fan, the reason he is a singer now is because he used to be a professional surfer and one time at Pipeline, he fell off of a wave and landed face first onto the reef. He gave up surfing after the accident.)
There are many factors that go into making a good waves for surfing. I hope I made some of these clearer in my post. Post any questions if you are confused and I will gladly answer them.
Here is some video of Pipeline at its finest:
In a future post, I will be looking at wave breaks from all over the world and possibly ranking them. Pipeline will definitely be one of them so if you would like more information on it, wait for that post.