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What bizarre surfing utopia is this? Meet circular wave pools 2.0

A new circular wave pool design by SurfRing could break the never-ending-ride barrier as a group of South African engineers tackle the wave pool world’s Holy Grail…

Octogenarians want the fountain of youth, gluttons search for the ever-expanding, unlimited buffet and surfers seek an endless wave. Literally. A ride so long that the only acceptable ending is your legs collapsing under you in blissful exhaustion. And a round wave pool may be able to offer that elixir of stoke. This is the wave pool Holy Grail.

A circular wave pool can be done on a fraction of the land size required compared to most wave pools and cost a small portion of the price. So why hasn’t a circular wave design morphed into reality? It’s not like there haven’t been plenty of contenders over the years.

We’ve previously covered the history of the Circular Wave Pool, but here’s the abridged version…

surf ring scale wave pool model
SurfRing’s scale wave pool model showing the wave formation and potential backdrops.

Kelly Slater Wave Company, WaveLoch/SurfLoch (Tom Lochtefeld) and Perfect Swell all touted circular wave pools around the time of their inceptions. And all 3 have since deleted versions from their websites and media.

This leaves only Greg Webber – an early proponent of the rounded designs – and Okahina who’ve been promoting these pools in recent times.

Greg’s has an oval-shaped track or moat. Waves are created by motorized carriages with an attached hull. It plans to use two types of water displacement: one to create waves, the other to make currents. We’ve yet to see a working model.

And Okahina’s is a floating atoll, made for existing bodies of water, which pushes out waves from its central hub. It’s touted to produce a wave every 15 seconds and offer 30-second rides. A full-sized version was due to launch in late 2020, but so far, nothing has eventuated.

circular kelly slater wave pool
One of the early Kelly Slater wave pool designs was circular, a concept which has always worked better in artist’s drawings than in real life. SurfRing is hoping to change that.

Recently, another company has arrived on the circular scene. SurfRing, the name is as simple as the concept is alluring. But beneath the surface of something so seemingly straightforward lurk some serious technical hurdles. The main one being current mitigation. Or in non-engineering speak – how to overcome the problem of current and wake from the previous wave negatively affecting the following wave – potentially having too much wash and stirring the trough and face of the next peeling gem. Turbulence and currents are hard enough to manage in regular wave pools, but in circular pools, the effects are magnified.

We had a chat with Peter Calitz, SurfRing’s Founder, inventor and CEO, who breaks down the entire system, as well as the company’s future goals as he outlines the seemingly boundless possibilities – and scalability – of SurfRing’s design.

Why do you think there are no commercial circular wave pools in existence right now?
All circular donut-shaped wave pool ideas I have seen are based on propagating waves, which is hard enough to perfect in large rectangular pools, but in circular pools, turbulence and currents are amplified.
 
Do you have a current mitigation system?
Current mitigation is based on the head-flow water discharge being slightly counter-rotating, which cancels out the stirring effect.
 
If a surfer falls off a wave can they easily get back to a calm area / not impede other surfers?
Like the ‘Unit’ floating wave machine, to fall off is to be washed off the back into the lake or pool where there is plenty of depth and space to paddle back and to re-join the line up for your next wave.

How does Surf Ring create waves?
Our system is based on the convergence of deep-water sheet-flow with intersecting ‘wave-forming mound’ (snowplow) which derives its movement from the carousel. This wave forming mound snow-plows into the oncoming water sheet-flow. Tom Lochtefeld might call it a traveling reef. The pilot project will have several large axial-flow pumps, like the Unit wave, City Wave and American Wave machine’s Surf Stream.

How about the water flow rate?
Typical ‘sheet-flow’ waves such as ‘City-wave’ require a decent flow rate, perhaps about 10M/sec to achieve a reasonable wave height. Our waves are very different, more like ocean waves, where water having only a relatively low flow-rate, is lifted almost vertically by energy from below. Similar to flipping an omelet, where the traveling wave former (spatula) gets in underneath the water (egg), lifting it up before it can slide off the wrong way. In this way, we can form large surfing waves without too much fuss. And perhaps in the near future with larger carousels, large heavy walls of water, which no one has yet imagined possible in a wave pool environment.

How large – and how long of a ride – do you predict the commercial versions of SurfRing will have?
Centrifugal effects limit how small a Head-Flow Surf Carousel can be, but anything above a 16-meter diameter is possible. A 16-meter carousel provides a 12.5 seconds ride for its biggest wave (1,8M) and then anything longer, up to 20 seconds for small waves (1M). It will have one, or two simultaneous waves, it can fit on the deck of a mega cruise ship, or it could take the place of your tennis court. My life goal is to build one larger than 100 meters in diameter which could create 10ft waves and have no less than 7 wave formers distributed around its circumference of 310 meters. I would divide its inner island ‘coastline’ into 3 ‘beaches’ of a 3-pointed star island shape, and at its 3 points have the waves die off then quickly rebuild for the next beach section. In this way each wave former rises and falls 3 times per rotation creating 3 rides (each) per rotation, translating into 1470 wave rides per hour of 23 seconds each, peeling @ 6 meters per second, which equals really big waves. Imagine what we could do with a 300-meter carousel! The sky is the limit.

I must emphasize that the design brief I set for myself many years ago was to create a system for wave pool surfing that reduces the cost 10-fold while producing waves that are much more ‘gnarly’ and much more desirable, not to compete with regular ocean surfing, but to compete with iconic ocean surfing. Note that, like Teahupo’o in Tahiti, the effective wave height in the SurfRing is greatly extended by its deep trough. So a 6ft wave has its crest only 3-4ft above pool water level.

The SurfRing team
The SurfRing team has a cost-effectibve approach to their circular wave pool creation.


 
How about energy consumption for SurfRing?
So the 30-meter diameter SurfRing featured in the scale model video has 3 simultaneous waves which each build-up then die off once per rotation, which results in 540 of 20-second waves per hour with a total energy consumption of approximately 540 Kilowatts per hour total. So 1 Kilowatt per hour per 20 second, 6ft wave.

Note that this example is a small SurfRing. For good locations, we have above 2000 waves per hour on a larger carousel in mind. This unrivaled output, low cost, and small footprint is the realization of our goal to bring affordable and meaningful surfing to the masses.  

I believe it is appropriate that such a breakthrough comes from South Africa. A Big Mac burger, which costs $5.51 in the U.S, is only $2.16 here, reflecting our currency which is hammered down 2 ½ times, to a point where we can’t afford American or European wave pool technology. We have no choice but to develop our own, meaner and leaner tech.

making the surfring prototype
Construction of the SurfRing prototype.

In the video, there appears to be a lot of water pushing up the face of the wave. How does this affect the paddle in?
The video model is not accurate. Other than the aforementioned problem that the entire pool of water is rotating, it has a 360-degree water flow that is even and consistent all-round, and it has hard static wave formers, which are both not correct.

In real life, expensive water discharge, although still 360 degrees, is concentrated ahead of the wave former where it matters, and at the paddle-in position this flow is slowed dramatically by means of a stationary restriction inside the volute chamber. In real life, the wave former is both soft and malleable, and the key to its function is that at the end/start of every lap (paddle-in zone) it fades and rebuilds. So when paddling in the surfer has a slower flow with a much smaller wave.  Another important feature is that the outer channel is also substantially blocked off just ahead of the paddle-in zone, which is the final barrier to undesirable current. Soon we will fully demonstrate these solutions with our larger model.   
One more point; perhaps the most fundamental answer to your paddle-in question, the concentrated sheet-flow described is aimed to have its front/leading flow boundary lagging just behind the leading edge of the wave former, with the effect that the former leading edge is, in fact, scooping up actual pool water, not head-flow water, inward and over itself. This means that the surfer paddling in is almost pulled or drawn into the front of the wave.
 
We understand you’re currently securing land somewhere in South Africa to build a scale model, yes? When do you expect this to be in operation?
Things are happening fast. Hopefully, we can confirm power and planning permission on the land within 18 months, at which time we will have secured all the funding. In the interim, we will have tested a large-scale test carousel (scale 1:5) to confirm the final design and engineering and complete the procurement processes. These are big tasks but we are making headway. Add 6 months for site development, installation and testing and we could open before December 2023.

Will it be open to the public?
It will be a public access facility with associated commercial development. And we are soon to announce a high-profile sponsor and a professional surfer who’ll be joining our team.


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