Surfing in Rivers
Underwater obstacles in rapidly flowing rivers and canals create turbulences and in some cases stationary waves. The basic phenomenon is the „hydraulic jump“ when rapid water hits into slower moving water*. Contrary to an ocean wave, these waves do not move across the standing water to break and disappear on shore. Here the water is moving against and over the standing wave, and the wave stays there as long as current and water level remain in this special interplay.
*) A special form are upstream moving tidal waves or tidal bores, which appear under optimal correlations of tidal amplitude, shore geometry and river current.
The physical effect, which allows a surfer to stay on the wave and not slide down into the trough, is basically the same on both waves: While the surfer slides down the face of the wave pulled by the downhill force, the water under his board moves up and tries to drag him backwards over the wave. By moving forward or backward on his board, the surfer adjusts its downward planing speed against the drag of the onrushing water and establishes an equilibrium between downhill force and drag force.
In a way, river surfing and its variations are the running-water-correspondents to all kinds of surfing activities on standing water.
Unfortunately, our rivers to not produce as many of these stationary waves, which can be surfed, as wee would like.
But there are lots of spots with a current fast enough, to get your board gliding. The necessary propulsion force is gained from a tow rope.
1: Riversurfing on Tow
When river surfing on tow, the surfer holds on to a rope which is tied to a tree, a bridge or any other fixed point alongside or over the river or canal and has himself „towed“ against the force of the current and is able to swing to and fro across the current like a pendulum.
This principle equals that of water skiing or –with surfboard – that of "freeboarding", where reversely the towing part is moving and the water is standing and cutting left and right between real or imaginative turning marks is called „Slalom“.
The necessary buoyancy is created by the travelling speed of the board relative to the water surface, with an inverse ratio between board area and required minimum stream velocity.
To practice this sport you only need to have a tow rope and a surfboard:
- a tow rope with handle, anchored to any fixed point at or preferably above the current
(recommended to start with a non-elastic 6mm-Polypropylene rope, length 15-20m, elevation of the anchor point 3-5m above the water surface,
experienced surfers who prefer riding upstream at considerably higher speed instead of simply crossing to and fro, use a rubber tow rope (Bungee-rope) and perform "Bungee-Surfing")
- a surfboard about 160 to 200 cm in length, 50-60 cm wide, 5-8 cm thick
Tow river surfing can be done at any section of a river or canal, wide enough to allow swinging to and fro across the current, and which preferably flows faster than 5 km/h ( ca. 1,4 m/s ). (this value relates to a board length of 2m.)
By turning the board in an angle to the current while pushing the downstream rail into the water the surfer can use the force of the current to accelerate across it.
The maximum speed relative to the water surface is reached shortly before the turn at the outer deflection of the pendulum.
Performance characteristics may be varied by changing the elevation of the anchor point, size and shape of the surfboard and the elasticity of the tow rope.
At fast flowing sections the surfer may use the upstream slopes of wakes or hydraulic jumps for additional thrust, which -depending on height and angle- may be even strong enough to replace the rope’s pulling force (rope gets slack) , which at this point will have turned to wave surfing. This is very similar to the effect behind a power boat, at the transition from freeboarding to wake-surfing, when the surfer pulls himself into the wake and feels the rope slackening while the wake takes over. Because ot this similarity a surfer from USA had called the wave at the Munich rafting canal the "River Wake". (which explains the term "Riversurfing "Wake" !)
Similar (related) Board Sports :
- Wakeboarding (formerly called "Freeboarding" when it was performed with normal surfboards behind tow boats )
Training Effekt for other Sports:
- Windsurfing (board feeling, balancing, arm strengthening),
- Water skiing (arm strength, feel of planing and edge effects)
River surfing should not be confused with:
- "Aqua-Planing" or "aquaplaning", the kind of riding or skimming over water on square or triangular planks (aquaplanes) behind towing boats (as sometimes defined in dictionaries),
- "Water sledding" (similar) which is also done on rivers and canals.
Contrary to River Surfing on Tow, here the board itself is being towed, and the rider holds on to the board by means of a rope or handles.
- "River-Boarding" , "Wave-Boarding" or „water sledging“ which may turn into a variation of river surfing like belly- or boogieboarding on ocean waves, when it comes to catching a river wake or a stationary river wave.
History of River Surfing
How did it all start? Read here Arthur Pauli‘s story about how he got the idea of river surfing and how the sport developed.
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