Surfer’s guide to Wave Energy
Wave Energy in Surf Forecasting
What is Wave Energy?
Wave energy quantifies how much power or “strength” waves carry, not just their height. Wave height is less important in the calculation of wave energy than wave period.
It is useful to know the energy of the surf as a benchmark as to whether the surf will be too big for your ability or too small to ride. It is also useful for selecting the surf spot as some breaks such as Uluwatu and Padang Padang can handle any size swell, while Bingin and Canggu breaks will max out above a certain size.
Key Factors in Wave Energy:
- Wave Height (H): The higher the wave, the more energy it generally carries.
- Wave Period (T): The time between waves; longer periods mean waves have travelled farther and carry more energy.
- Wave Group Velocity (C_g): The speed at which wave energy travels.
Wave energy in deep water can be approximated with formulas only involving wave height and period, but other variables used in the calculation are gravity and water density. Cold water waves are marginally heavier because the water molecules are more tightly packed together and so carry more energy. You can read more about the physics behind this in our Science of Waves guide.
The Introduction of Wave Energy in Forecasts
Surfline and other sites started including wave energy in 2010
- As technology advanced, surf forecasting platforms like Surfline began to incorporate wave energy estimates to improve the accuracy of predicting surf quality.
- Starting around 2010, Surfline and other sites began displaying approximate wave energy levels alongside traditional metrics like swell height and period.
- The goal was to help surfers understand how powerful the waves will be, not just how big they are.
Why is Wave Energy Helpful?
- Predicts surf quality more accurately: Larger waves with high energy produce more dramatic and powerful surf, especially important for big wave riders and advanced surfers.
- Distinguishes between similar swell sizes: Two swells with the same height might have different energies if one has a longer period; the higher energy wave is typically better for high-quality surf.
- Assists in planning: Surfers can decide whether to chase bigger, more powerful surf or settle for smaller, less energetic waves.
In essence, wave energy helps quantify the true power of incoming waves, offering a more comprehensive picture than height and period alone.
Impact on Swell Prediction and Surfing
- More precise forecasts: Including wave energy allows for better predictions of wave size, strength, and ride quality.
- Enhanced understanding: Surfers can gauge whether the swell will produce rideable, powerful waves or weaker conditions.
- Better decision-making: Knowing wave energy helps surfers pick the best spots and times, especially when chasing big waves or dangerous conditions.
Conclusion
Wave energy is a very helpful metric that complements traditional measurements of wave period and wave height. It provides a clearer picture of wave “power,” helping surfers anticipate the quality and intensity of surf conditions with greater accuracy.
For novices who are new to the art of interpreting surf forecasts, wave energy provides a simpler, easier-to-understand metric of how powerful the waves will be, which is the best indication of how big the surf will be.
Padang Padang Surf Camp have changed our planning of surf sessions to use wave energy as this is the easiest to communicate metric and we find it is broadly accurate. In Bali it never goes flat and the swells are constantly either increasing or decreasing in size. Wave energy helps to understand the trend of the current swell and how powerful the next swell is likely to be.
Now that you have a better understanding of wave energy, you are ready to read a swell forecast but to be fully prepared, it is better to also read about winds, wave height and wave period.
If you are interested in the technical and scientific aspects of surfing, then our Beginner, Intermediate, and Advanced Video Surfing Tutorials are for you.