90 degree turns in river

I recently did the Rio Chama in New Mexico and had situations where the river took a hard right or left turn with increased speed and rapids. My concern was the rock walls on the outside of the bend. I would like to know how to approach these hard bends in the river without being pushed into the wall. I’m looking for direction on which side to approach (out/in) and how to best position the boat in relation to the change of current. Any suggestions? I tried to make my boat parallel to the current I was entering so I could try to continue to navigate down stream. I did hit the wall and flip my boat in one of these situations. I own a 16’ solo river tripping canoe. Thanks for any help.

I’ve done the Chama below the
Monastery, but it sounds like you may have been higher in the canyon. The behavior of the water in a tight loop is complex. I just read a serious article by a river hydrology person, and I’ll have to go back and post a link.

Here’s a problem. Some of us have been confronting your situation so long that it has become automatic. I simply can’t say what I do about those turns, though I must have done it dozens of times in Slickrock Canyon on the Dolores.

As a first approximation, I suggest staying as far inside the bend as shallow water may allow. It may surprise you, but the through-current is actually higher and more direct on the inside. What happens toward the outside is water on the surface heads for the wall, and then rolls down against the wall, and under, in a sort of underwater spiral.

So when you stay “parallel to the current” you may imagine that you can track the current right around the bend, but as the water nears the wall, it isn’t tracking the bend real well. It’s taking a dive, and can take you with it. Be a bit more proactive and try to stay inside on the bends.

If you were a tandem, I would tell you to backpaddle while you point toward the outside of the bend, and your tandem would seem to go around the bend sideways. If you were in a whitewater solo like mine, you could spin backwards, and keep an eye on the wall behind you as you go around. But in a tripping canoe loaded with gear, you just want to steer through the bend on the inside, not pointing at the wall.

Lots of ways.

– Last Updated: Jun-10-12 11:54 PM EST –

In the long run, your best approach is to learn all the basic ways of maneuvering. Then you can pick and choose or mix and match various techniques to individual situations. In the meantime, here are three specific possibilities that come to mind. In each case, let's assume you are rounding a very sharp bend to the right, so that the rock wall you wish to avoid is on the left bank.

1. Aim the boat to the right of the "apparent" lines of current flow (see g2d's comment about spiral currents) as your round the bend, and paddle forward. That of course will cause the canoe to want to pivot sharply to the right as the front end of the canoe gets snagged by the slower current toward the inside of the bend while faster current acts upon the stern, but you can counteract that easily in most situations by paddling on the right, even changing your power stroke to a sweep if the pivoting action gets too strong.

2. Side-slip the boat. If paddling on the right side of the boat, do draw strokes, and if paddling on the left, do pries. These can be ordinary draws and pries or the sculling variety. An average multipurpose solo canoe can go sideways at about 3 mph if you put some muscle into it, which is enough to salvage some pretty crappy mistakes and make them end up looking pretty graceful. A very effective stroke for "oh-crap" situations is a reverse wedge on the left side, which slows, stops, or even reverses your boat while simultaneously pushing it sideways. Initially the boat goes diagonally forward, but by the second or third stroke it is going straight sideways as the current passes you by, and by the third or fourth stroke the boat is going backward fast enough to make rearward progress against the current and is going diagonally backward (all this varies, depending on current speed). Usually, this is a quicker course correction than steering when faced with last-minute maneuvering. Also, any method using draws or pries can be combined with method #1.

3. Backferry around the bend, or at least during that portion of the bend that is most risky. Point the bow of your boat a little toward the left bank and paddle backward. The boat will be moving through the water backward, but relative to fixed objects in the river, like that rock wall you want to avoid, the boat will be hovering in place or moving slowly downstream while simultaneously traveling to the right. You won't need much angle to the direction of current flow in most cases, but in any case, tailor the angle and paddle power to the situation to make the boat move crosswise across the channel, or to prevent it from moving crosswise in the wrong direction as you move around the bend in a controlled drift. In swift current, a backferry that is initiated by, or combined with, a reverse wedge can save you from hitting that rock wall in pretty severe situations.

Spiral currents on sharp bends.
Yes, this is a fascinating phenomenon, which you can often see happening if you look closely. The end result is that the current at the surface really IS flowing at an acute angle toward the outside bend. I’m far from an expert, but have found that like many other aspects of swift water, one gets pretty attuned to this type of flow and can be ready to counteract it ahead of time without thinking too much.

Start early, paddle hard
As you approach the turn you need to be turning your boat to the inside. By the time you are in the turn you should be paddling hard across the current to the inside. The water wants to throw itself against that wall, and you with it. Start your move before you get there and accelerate, no lilly dipping.

Often, there is a cushion of water against the wall, and sometimes that can save you. The cushion rises up on the wall, and from what G2d says, sounds like there is some water that dives. But usually you see water upwelling on the outside of the bend, so it is not all diving. A very hard thing to remember and to do, is lean toward the wall if you get to that cushion. If you lean toward the inside, the current usually will roll you right over. But that cushion can sometimes save you from bashing the wall.


Helical flow
Flow through a 90 degree bend will generate helical flow, sometimes called secondary flow. A simple diagram and explanation is here:


Helical flow is just rotational flow superimposed on straight line flow. As the water moves forward, it simultaneously rotates. Another way to think of it is that as the water flows into a bend, inertia causes it to flow straight ahead until it strikes the wall in front of it. Faced with the obstruction, the water must move downward, creating rotation.

Seeing the streamlines shown on the diagram linked above should give some idea of how to paddle your way through the bend. It is very much like ferrying across a current, except in this case the current is turning.

Note that in the description, there is mentioned the occasional presence of a secondary cell with opposite rotation. I’d wager this is what gives rise to the ‘cushion’ mentioned by Booztalkin: a portion of the current that hits the wall rotates ‘up’ rather than ‘down’, causing a wave at the wall.

Your posts title says it all

– Last Updated: Jun-12-12 3:24 PM EST –

as far as I'm concerned.
"He who hesitates is lost" or in this case; thrown up against the wall
In fast CFM water, I always am scanning as far ahead as I can see just as I do in heavy interstate traffic at 70 MPH watching for those brake lights in the distance, so I can take evasive action

jack L

Back paddling to achieve a
difference in your boat speed and current speed, to maintain control is such a lost art now. It works very well to allow you to change the angle of the boat as you progress downstream to catch the best current that wont slam you against the rocks.

On the Snake in the Yukon there are canyon wall with a 90 degree bend after a Class III rapid. There is a cushion wave but you can bang hard into the wall under power…Backpaddling allows the cushion to work.

Here in New England the outside of the turn is to be avoided at all costs. Our WW is usually in the spring and laden with strainers on the outside of the bend…

What others have said is good advice.

What canoe?
And, how wide is the river at those turns?

In general, assuming my goal is to pass through as efficiently as possible, I’d be trying to stay in the center, not so far to the inside as to get caught and spun by the eddy, and not so far to the outside as to be shoved into the bank. Then I’d be matching my turn to the current and paddling hard.

But some hulls turn easier than others. And each bend in any river will have unique features, outside pillows and strainers, inside eddys, width of river vs length of boat, current speed, etc. Both the hull and the river will dictate exactly what I might do at any given turn.

Thanks for the replies (all of them). It was helpful and I have some ideas on how to approach the situation in the future.

As others have said …
… unless you can see the spot and knowing what kind of boat, it’s hard to say exactly.

But one thing is keep your paddle on the inside of the bend. Your paddle can’t do you any good if it’s wedged between the hull and the rocks. And keeping your paddle on the inside allows you to concentrate on making the move, not worry about losing the use of your paddle.

learn your strokes…so that you can

– Last Updated: Jun-11-12 11:47 AM EST –

then PLAN for those unexpected moments. What you're talking about is knowledge of stream/river structure (ie current behavior)...and practice making the bigger moves/changes with your boat in water that'll let you do it.

Backpaddling is one thing that solo
canoeists in ww boats find a bit difficult. Enough so that we often choose an alternative.

But for a tandem, especially a loaded tandem, backpaddling is a skill that must be learned and maintained.

What’s true for a tandem is true for …
…most solo canoes, which of course means the ones that are not highly specialized for whitewater. Though I’ve never paddled a canoe that spins as effortlessly as a whitewater canoe does, I can imagine that backing up with one would seem like a poor option. The original poster has a “river runner”, which might mean different things to different people, but in any case, it is a 16-foot solo boat so odds are it won’t exactly spin like a top.

Continuous Draw Stroke
In those situations I set my paddle on the side of the canoe opposite of the problem - in other words on the inside of the bend.

Start very early and draw continuously away from the outside. I try to never take the blade out of the water. Draw hard and once the blade is back to your seating position then knife the blade thru the water(turn 90 degrees) to the front of the canoe and repeat.

In this approach, no forward strokes are used, the river provides that energy, just a consistent draw away from the problem.

I agree that a good approach to this
is to get yourself set up on the inside of the curve going slower than the current with the stern angled away from the wall - if you really slow down you can paddle through in complete control. I use this approach a lot whether I am paddling solo or with a strong partner.

Paddling the Yukon

– Last Updated: Jun-11-12 11:09 PM EST –

Paddling the Yukon taught me a lot about helical flow before I knew there was such a thing. I've been there 3 times, once on the 460 mile Yukon River Quest, and twice in the Yukon 1000 mile race. As bowman in a voyageur canoe I have a first hand view of the complex surface currents and turbulences with respect to the shore and river bends, and the effect on our canoe. It is quite dramatic. In studying the river flow and thinking about what it does after my first and especially the second visit, at home I drew a diagram that exactly matches what I later saw in academic print of the helical flow effect.

The Yukon is an amazing body of water, a combination braided and meandering river. Much of it is a half mile wide (much wider in the "flats"), with meanders averaging a mile to a mile and a half, rarely as much as two miles apart. The current flows fast most everywhere, up to 6 mph or even more, but does not break into whitewater (except at two very short sections). But turbulence abounds. I learned to interpret what might in ordinary rivers look like ripples caused by shallows ahead, instead understand them as colliding currents and to predict the effect on the canoe before we arrived. Doing so helped immensely in keeping on course, or in changing course to take advantage of better current.

In more average slow moving rivers we paddle, we learned to watch, predict, and follow the current that was usually more laminar, not helical. That meant generally being fastest in long sections at mid-stream, and to make the trade between faster current/longer distance on the outside bend, vs shorter distance/slower current (or even reverse current) on inside bends. Most often the "rule of thirds" seemed to apply... either a third of the way from inside or outside gave the same overall result.

Not so on the Yukon. Approaching a meander, getting caught in the helical surface current meant battling a 6+ mph current taking us rapidly a half mile or more to the opposite shore, vastly increasing both our distance and time. On long straight sections we tended to gradually head cross-river toward the inside of the next curve. If we waited too long to get there from mid-river, the cross current could suddenly appear and sweep us away. Several times, even well before reaching the curve, we discovered we were caught too late and had to sprint paddle with all our strength for several minutes turning fully 90 degrees toward the inside bank.

Eventually we learned to predict exactly where we should be, and I could verify a rapid change in current upcoming by the telltale surface ripples. There is most often a definite line where the helical current begins when approaching, but not too close to the inside of the curve. Not too venture too close otherwise get caught in slack or reverse current upon rounding the curve. The trick is to watch that rippling edge, stay in the fast current until it begins to break left or right, and stay just inside of the break, then head 45 degrees around the curve to stay in some laminar downriver current and shortest distance.

One more thing about the Yukon... it constantly calls you back. I will return with even more respect and knowledge of how to play that river.

as stated above and…
work your way to the side of the river away from the wall agressively and early…do not stay parallel with the current. It is going to the wall. You need to cross it and keep crossing it to stay on the inside of the turn away from the wall. If you eddy out in the process, so be it. At the most extreme you will be paddling strait toward shore or even ferrying upstream as you round the bend. Whatever it takes to stay on the safe side of the river and near shore. Watch out for shallow boulders as you paddle at angles to the current. Hitting them sideways is not good.