For us flow, hydraulic drop, currents, eddies, obstructions and numerous other factors are the difference between driving through our next carves or not. My passion (and job) is designing waves that not only deal with these dynamic factors but optimises them to create high performance surf waves. How do we do it? One key aspect is adjustability.

Waves Are Extremely Sensitive

A wave is a single point on a spectrum. Above this point is a range of breaking waves and below this is a non-rideable green wave and below that further is a hole (see previous article The Two Types of River Waves on Riverbreak).

For a given set of flow/river conditions there is one specific wave “sweet spot”. This is why some waves only work at very specific flows. You’ve maybe looked at the micro flow effects at your local wave and perhaps noticed the delicate dance the water makes. A small boil or seam from an upstream boulder or a curved current that carries through the wave making it break more or less. Bottom line, waves are extremely sensitive.

Check out how the wave sweet spot is a single point in the video below. This sweet spot is super sensitive.

To further complicate the issue, we want to surf most of the year, at various flows, not just a few weeks a year. And, oh yeah, we surfers are pretty picky about wave shape too. Adjustability allows the wave to change in order to find the sweet spot, stay in it and create the wave shape we need to surf. I’ve designed waves that work with no adjustability but my experience has led me to include adjustability of some kind in all designs.

What Does Wave Adjustability Look Like?

I’ve used several types and have seen countless others. Adjustability typically manipulates one or more of these factors: flow, drop, angle, or bottom contour. Adjustability falls into two categories: real-time and static.

Real-time Adjustibility

Real-time allows adjustment with water flowing whereas static adjustability requires flow to be turned off or diverted around the wave. Examples of real-time systems include The Wave Shaper in Boise, Idaho which adjusts the bottom using pneumatics and hydraulics, or the Alm canal which uses a mechanical screw system to move a plate on the bottom.

In the video below, you see Ryan Richard, the Wave Shaper operator, making the adjustments remotely from the middle of the river on his laptop. Pretty cool right? Even better having Gerry and Tao from Munich in Boise slaying it.

Static Adjustability

Static systems typically attach blocks or other shapes to the river or canal bottom. Although the wave can be adjusted to changing conditions, the flow must first be turned off or diverted around the wave before. Most of the rivers however, are not designed in a way that the flow can be turned off or diverted spontaneously.

The photo below shows Columbus Georgia – this is a “static system” not a “real-time” adjustable feature. We actually never had to do anything to it after it was built worked right away (lucky or good? – who knows a bit of both probably).

Spot: Columbus Wave, Georgia

Pros and Cons

There are pros and cons to each system. Real-time adjustability is typically more expensive to construct initially but reduces costs during tuning and is a good option in rivers or other situations where flow varies (like a river) and flow can’t be turned off. It can also achieve very fine adjustments difficult to do with a static system.

A static system tends to be less expensive up front and is a slightly less complicated design but can require a lot of iterations during tuning to get the wave right. So how do you know which system is best? That’s a tough question. There isn’t a one size fits all system. It needs to be evaluated project by project based on site, budget and performance expectations.

Does Adjustability Guarantee Wave Building Success?

No, but it does improve the chances for success. You can’t compensate for a bad design with adjustability. There have been wave projects built with extensive and costly adjustability that don’t work well. Adjustability will never replace a good, fundamentally sound design that is already near that wave sweet spot.

It is usually cost prohibitive to make waves excessively adjustable or the site doesn’t allow drastic changes to the channel after the wave is constructed, so you have to be close to begin with. Knowing where waves are sensitive and which characteristics are needed is the key to successful adjustability. My approach is to design adjustable features with the precision needed for a non-adjustable wave then build in the adjustability from there at sensitive locations to dial in the wave.

River Waves are a beautiful thing. Let’s keep progressing surf wave design to bring quality river waves to a town near you. Include adjustability in your next wave project, trust me it’s worth it.

To health and high water. See you on the river!

The post The Case for Adjustability in River Wave Design appeared first on Riverbreak.

“Through our work with the boating community,” notes engineer Ben Nielsen, “the new feature will be a great place to surf for hours, even at low flows. When we opened it up the level was 600 cfs (cubic feet per second) which is pretty low, but when we were able to board surf and play boat it easily, everyone was super excited. Being able to utilize the park at low river levels will extend its season, and therefore increase its value to the community.”

The wave is a great place to surf for hours, even at low flows.

MWDG was called in to improve a safety issue in late 2013, and helped the County formulate a plan to replace one particular feature so that it would require little or no maintenance. Funding was granted in December, 2014 and MWDG designed and bid the project in January, 2015: construction started right away due to the importance of improving river safety, and the project was completed in March.

Gunnison County project manager John Messner notes, “It is important to have turned this feature into an asset. It makes me really happy to know we made it happen in the short timeframe – in fact, with a bit of time to spare. Credit goes to those who that supported the project with time, energy and funding, besides of course the McLaughlin Whitewater Design Group: Gunnison County, City of Gunnison, Great Outdoors Colorado, 1% for Open Space, the  Gunnison River Festival, Western State University, and the Colorado Water Conservation District.”

Spot Details

Country: USA, North America
Nearest town/city: Gunnison, Colorado
River: Gunnison River
Address: Gunnison Whitewater Park Gunnison, CO 81230
Directions: The Gunnison Whitewater Park is less than a mile east of Gunnison City on Hwy 50. Take U.S 50 east from Gunnison and take a left just after crossing over the river (there is a big sign).
Latitude: 38.5320625
Longitude: -106.9501801

Wave Details

Characteristics

On the photo above the river is low but the wave is super fun. It gets much bigger at higher flows.

River Gauge

Weather in Gunnison, Colorado

Today 09/02 High 23° / Low 4°

Tomorrow 09/03 High 21° / Low 4°

Tuesday 09/04 High 22° / Low 4°

Spot Location

More on Gunny Wave

Gunnison Whitewater Park on Facebook
https://www.facebook.com/pages/Gunnison-Whitewater-Park/204513186250193

Gunnison River Festival
http://www.gunnisonriverfestival.com

Gunnison River Festival on Facebook
https://www.facebook.com/pages/Gunnison-River-Festival/197666413659532

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