For years now, engineers have endeavored to generate artificial waves in wave pools. Surfable artificial waves, in particular, have been somewhat of a holy grail. Artificial waves only produced weak waves not suitable for surfing. Some of you might recall the 80’s movie ‘North Shore’ where Rick Kane won a wave pool surf competition among dismal artificial waves and then traveled to Hawaii with the prize money to surf real waves.
In recent years, however, surf-quality artificial waves are no longer just a fantasy. In particular, Kelly Slater’s wave pool hosted a World Champtionship Tour (WCT) event where the world’s best surfers competed. Judging from the video below, it looks like the waves are generated by a big train that drags through a body of water.
Apparently, Kelly Slater has been a prolific inventor and has several wave patents to his name, one dating back as early as 2008. Considering, however, that video of his working wave pool surfaced near the end of 2015, I think some of the newer patents may be more interesting. In particular, US 10066401B2, which was filed January 13, 2017, describes and claims wave generating features that are surprisingly simple in concept.
A patented claim describes a) the bottom contour of the pool, and b) a foil-like structure that is dragged through the pool to generate a wave. A cross-sectional drawing showing the bottom contour is shown below. The bottom contour has a deep part 202 that slopes up to a ‘sill’ 206. A foil is dragged lengthwise through the deep part. This causes a wave to break above the slope and the sill.
The ‘foil’ 500 has a leading surface 502 that creates the wave (when dragged through the pool) and a trailing surface 504 that is shaped so that the trailing surface does not create additional little waves that might disrupt the main wave and cause unwanted drag on the foil. This appears to be one of the problems in wave generation, in that it is hard to generate a single large wave as opposed to multiple little waves that can interact and disrupt each other.
In nature, surfing waves are generated by wind, far out in the ocean. These waves are jumbled and unorganized and not yet suitable for surfing. Those waves travel hundreds or thousands of miles, during which, they gel together to form surfable waves. In the case of artificial waves, the wave energy must be formed in a way so that the energy is concentrated and organized from the beginning. Thus, Kelly’s foil, in combination with the pool shape, appears to concentrate wave energy very well to generate some surfable waves or ‘nuggets’.
Kelly Slater does not, however, have a monopoly on artificial waves. Others are also jumping into the fray. One interesting wave pool recently released a video. This technology appears to use a giant plunger to create artificial waves in multiple directions in a single plunge (see below video). This can potentially allow for different peaks and more waves than Kelly’s model, which apparently generates one wave at a time.
If you want to read more about Kelly’s wave patent, here is a link: http://www.freepatentsonline.com/10066410.html