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River Swimming

                                                                                           - Jim Simmons

Whitewater streams, rivers and creeks are powerful, relentless, and predictable. Understanding the dynamics and forces of river current and how the water pressure behaves is crucial when river swimming. Swimming self-rescue is the ultimate self-rescue tool for river boaters. If you've not had training in swiftwater/whitewater rescue, such strategies as discussed here can also be used when assisting or rescuing other paddlers who may be stranded or need help. Enroll in a rescue workshop soon and practice these techniques.

River hydrology and current differentials require swimmers to utilize different strategies. For example, we can apply the PREDICTABLE part of river behavior to our advantage, but we must correctly 'read' the river current's action. Most commonly described in rescue sources are two current actions: a) laminar flow and b) helical flow. In a river channel that has a classic downstream 'V' the water moving along the bottom of the streambed is slower, because of friction, while the surface water is moving faster especially right in the middle. Just under the surface in the middle is the fastest current, exactly where an unwary swimmer will be funneled--referred to as 'laminar'. As the river gradient descends and the volume of water within the banks increases, particularly when the stream begins to narrow, large waves form and pile up into what look like 'haystacks' in a hay field. The river's energy and volume has to dissipate somehow because the same volume of water that passed a wide place in the river is now moving past a more narrow space.

As the river current continues its journey downriver it drags water from the shorelines where the river bottom is now sloping upward into more shallow places. This water is replaced by water being pulled from the river bottom. The resulting action corkscrews back to the surface in a circular, helical action and is named the 'helical' flow. Smaller circular corkscrews occur inside the larger circular patterns. This helical action makes it difficult for swimmers to swim into shore or into a safe eddy if not aware of this helical action. Both the laminar and helical flows want to keep a floating object (you) in the middle where the current is deepest and fastest (and predictable).

The general direction in which the water flows is referred to as the current direction (or more technically, the current vector). Correctly reading the current is important for both boaters and swimmers because the angle of ferrying (both in a boat and when self-rescuing) should be assumed in relation to the current direction (vector), not necessarily the alignment of the river banks. For example, if the river curves a turn, the current may not follow the turn exactly but instead, both the helical and laminar flows may pile up to the outside of the turn (usually the deepest). In negotiating riverbends the so-called safe' side will usually be to the inside of a bend where the river bottom slopes upward into shallow places. The outside water will be deeper and faster and may contain strainers and debris piles because the force and weight of the water frequently topples trees or floats objects that have been collected on the surface.
When performing a wet exit from your boat (missed your roll), think first of the classic rescue refrain---"immediately get the feet and legs to the surface and move to the upstream end of the boat." Always try to self-rescue both self and the boat but if danger is lurking downriver, release the boat hoping paddling friends can retieve it.
When towing your boat, get into sidestroke posture, jerk the boat into a ferry angle with the upstream end angled in relation to the current direction and pointing diagonally toward the destination shore. If you didn't retrieveyour boat, and there is no danger below, in past eras the recommendation was alwas to get on your back and assume the defensive swimming posture with feet/legs downstream and toes breaking surface. As you float along, if you must negotiate rocks/obstacles use your feet/legs as shock absorbers to push off and maneuver as needed. Your arms and hands become your paddles as you make backstroke actions when necessary. This defensive posture allows good vision for what lies ahead.  In the modern era of boating it is generally best to transition to your stomach and aggressively swim to shore, even if there is no immediate hazard below your position.
Let's assume you realize you need to exit the river faster than described above, because you suddently spot some danger ahead. In this case, angle your back to the current direction until you are just about perpendicular to the current direction. Swing the knees/legs around (keeping them at surface) and transition to your stomach in the forward crawl. Begin stroking aggressively with your head up and looking downstream. This 'head-leading' position is the same maneuver you take when the bow of your boat is leading as you drive for a target eddy that you want to catch. It is also the same stragegy to use if swimming up and over a log strainer in the water. It is vital to keep the head up and eyes focused on the target. Some call the aggressive crawl posture an 'offensive' maneuver.

Your objective in this aggressive action is to try and swim faster than the current speed while moving toward your destination. Since most lifevests with the traditional amount of buoyancy (16.5 to 17 lbs) won't keep swimmers on the surface in very turbulent water, this head-leading action helps you float higher (sort of like walking on water) because of the current pushing on the back of the head and shoulders moving you along. What about getting sufficient air to breath? Without consistent practice river swimmers don't manage their breathing very well and frequently ingest water impeding proper breathing. A main point to remember is to do your best to relax and get into a rhythm with the waves and turbulence. Turn your head and exhale out if about to get splashed. If swimming waves, exhale as you break through the wave crests and inhale as you go down into the next trough (depression). This is why practicing your river swimming often is necessary, otherwise you'll hold your breath without realizing it.

As you swim for the eddy behind a rock, aggressive strokes and your momentum will be needed to break through strong eddy lines and to exit turbulent waters. Remember, both the laminar and helical flows want to keep swimmers in the middle. Just as you swim from the river current across an eddy line your head will go across first. You legs will then be dragged downstream at this moment, so you have to hit overdrive to stick. Just as you cross, barrel roll your body and continue to roll into the eddy water so you'll stay safely in the slack water. Keep swimming forward until your hands, feet and knees touch bottom--in other words, "crawl before you walk", a stragegy to prevent foot entrapment. If you swam for the eddy rather passively you may well drag out the bottom of the eddy and continue downstream.

Summarizing the Key Strategies:

A) Defensive position. Roll onto your back with the feet downstream to act as 'shock absorbers' if encountering objects in the water. Keep the toes at the surface and if you slide over ledges or flat rocks, arch the back and become a "floating straight board" in the water, but also keeping the hands at the surface. Use the arms/hands in a modified elementary backstroke action to scoop water and redirect the body position to the main current--always keeping feet downstream. This is called 'setting an angle to the current direction'.  Even if there is no threatening hazard below, it is best to transition to the stomach for the forward crawl and swim aggressively to shore. 
B) Aggressive swimming. This is an effective way to get to a desired target quickly, and because the head is up you will be able to keep focused on your destination. You'll be facing downstream with the head up which has the advantage of speed. Just as in boating strategy you may need to be swimming 'faster' than the current is moving to hit your target. When you arrive at the eddyline, use the barrel roll to corkscrew yourself into the eddy water so you will stick.
Sometimes, if the current is more gentle you may use an offensive forward ferry technique. In this instance, face upstream at about a 45 degree angle and use the freestyle crawl to reach a spot across the stream. It is best to start high enough upstream that you won't miss you intended landing spot on your destination shoreline.

C) Swiftwater entry into moving water. Because you may not know what is below the surface, a special entry is made (rather than diving as in a pool). Wade out into the water to at least knee depth. Cross the arms in an 'X' at the wrist, with the hand either making a fist or slighly cupped. This protects the face and throat area. Launch into the water with the back arched and the head back, landing on the PFD and the chest as you execute the entry. Flip the legs up behind the body as you land. If you roll over to swim defensively, do so horizontally to avoid entrapment or injury to any part of your body.

For swimming action in hydraulics, review the article this corner on Low-Head Dams and Hydraulics. Watch for more to come on river swimming strategies.

Jim Simmons, 1/20/2010
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