Pressure differential.

– Last Updated: Sep-09-12 7:32 PM EST –

All current is, is water moving under pressure.

When the boat is aligned perfectly to this pressure, the pressure is the same on both sides of the boat. Move the bow out of alignment, and the pressure is greater on the side facing the oncoming current. Press more on one side of the boat than the other....it turns. Release the pressure (by raising the bow), and it turns less. Release the pressure and add counter force, and the turning can be controlled or reversed.

edit: Before the protests start - "turn" in this context, is referring to departing from the upstream direction. I know that a boat generally turns easier with the bow out of the water. We're talking about maintaining an upstream direction here, so everybody try to stay focused.

Increase the pressure differential (by putting the bow deeper in the water) and the force required to overcome the current (pressure on the bow initiating a turn) increases.

GBG - the only time that poling is mechanically different than paddling is when the pole contacts a stationary hard object. When thrust has been accomplished and the pole is lifted to prepare for another plant, the boat is doing what every boat does in relation to the current. Much of the time when poling, ferrying is accomplished without solid contact.

When traveling upstream on a meandering river(now we're progressing beyond "basics"), you find yourself ferrying from one eddy on the inside of a bend - across to the eddy on the opposing inside of the next bend. When doing so, you often cross water that is too deep to pole off the bottom - so the ferry is completed by "kayak-stroking" with the pole, just as if it was a double paddle. So now the "poling boat" is merely another boat - doing what boats do in current.

Edge the boat, trim it bow-heavy or bow light....it will react to the current the same way, regardless of propulsion. Poling off the bottom doesn't change the dynamics of the boat on the water - it merely provides a more positive thrust or leverage....for a series of moments.

Rock describes a practice routine in his book and demonstrates it in his video. Facing the current in the boat, the pole is planted but no forward thrust applied - the boat is merely held in place. Now - by simply edging one side or the other, the boat turns back and forth across the current. This demonstrates the pressure differential on the front of the boat as the bow departs from alignment with the current. You can both see it and feel it.

You can do the same drill while changing the trim of the boat between bow light and bow heavy, and it becomes immediately evident which condition will give the most control.

All this translates to paddling, because the dynamics of the current interacting with the hull are the same.

Still photos don’t tell us much…
…do they?

I studied photography and photo-journalism way back in another life. One of the first things you learn in that study is “pictures lie”. This is especially true if you concede that a partial truth is no better than a lie.

Video - while still only partial truth, due to it’s two-dimensional limitations - tells a much better story. Unfortunately, there seems to be a lack of good videos showing the mechanics of upstream poling or paddling on the 'net.

One example for illustration

– Last Updated: Sep-09-12 8:19 PM EST –

You understand the principles of controlling the boat in rivers, but I'm not sure you understand the really basic principle I was trying to convey. I'll pick one of your points to try to illustrate the difference.

You said "Facing the current in the boat, the pole is planted but not forward thrust applied - the boat is merely held in place. Now - by simply edging one side or the other, the boat turns back and forth across the current. This demonstrates the pressure differential on the front of the boat as the bow departs from alignment with the current. You can both see it and feel it." This is perfectly true and very easy to visualize, though I must disagree with your wording because thrust IS being applied. That thrust is the force that causes the boat oppose the force of the current as that current goes streaming by. The force supplied by the pole is like that supplied by the string that holds a kite in the wind, In both cases, this is a force supplied by an external source. When held against the current in this way, water is flowing by the boat, and thus changes in the hull's attitude will control what the hull does. The same can be done with steerable kites, but a kite can't fly if simply turned loose in the air, and your boat won't do what you describe if not held in place by an outside force. When the boat is moved against the current by paddling, the force applied comes NOT from an outside source, but from the same water as that which supports the boat, and this is the key difference I tried to describe. In this case (ignoring turbulence, which as I pointed out, is where the control difficulties come from), the boat will act in the same way relative to the water itself regardless of which direction you make it travel.

Have you ever learned vector analysis, such as for studying dynamics of motion? If you know how to do that, this can all be illustrated mathematically and in diagrams - it's extremely simple to do. If not, surely you understand that in a current that moves 3 mph, if you paddle upstream at 4 mph, your total speed relative to the stationary river bottom is 1 mph, and if you paddle downstream at 4 mph your speed relative to the river bottom is 7 mph, but in EITHER case your speed THROUGH THE WATER is still 4 mph. It gets a little more complex when traveling at different angles to the current (here's where you need your trigonometry) but still your through-the-water speed is 4 mph (that's what my floating-swimming-pool example was supposed to illustrate). If you can understand that principle, it's really a very small step to understand that under paddle power alone, the hull responds according to what the paddle does, and from *the frame of reference of the water alone* (ignore stationary objects on shore or attached to the river bottom), the motion of the hull through that water is always the same.

There have been occasional posts here by sea kayakers, describing how they were happily cruising along at a fairly speedy pace, only to discover that their GPS showed their actual direction of travel to be backward because they were paddling against a current that was somewhat faster than their paddling speed. Without nearby visual references, all they saw was water streaming by the hull, just as it always does, so they assumed they were traveling forward. Well, they WERE traveling forward through the water, just not in relation to the ocean bottom. The same would be true for any other direction they chose to paddle in such current. In fact, a favorite vector-analysis problem in introductory physics classes proves that a boat can run rings around an un-anchored buoy, and a trail of "bread crumbs" left in the boat's wake as it does so will form the exact same pattern around the buoy whether there is current or not (only an independent view from a stationary point in space shows the difference between what happens with or without current. The people on the boat can't see this). It's also a neat way of illustrating that when out of sight of stationary objects from which to judge actual speed and direction of travel on the open ocean, no matter how strong the current might be, the current can only be detected by means of navigation aids, NOT by the performance of the boat when traveling in various directions.

I did a little experimental poling from a kneeling position (tippy solo canoe not suitable for standing), to see if I could work my way upstream through a riffle with current that was much to swift for me to paddle against. There were several times I tried to push off the river bottom in the same direction and manner as would be done when pushing with a paddle, and I totally screwed-up my boat control and made some really big mistakes. That's because I was accustomed to pushing with a paddle against water that my boat is traveling through, rather than relying on force applied via a medium which is outside and independent of that water - the stationary river bottom. In the absence of current however, there would have been no confusing difference between relying on paddle/water compared to pole/river bottom, because both would be stationary relative to each other. It comes back to what is illustrated by the old kite-on-a-string example.

Speaking of kites, here's another thought problem to illustrate my original point. You can fly a kite on a windy day if you hold the string while standing on the ground, but not while standing in the basket of a hot-air balloon (while in the balloon, all you can do is dangle the kite directly beneath you. You CAN'T make it fly). If you can understand why this is so, then there's nothing stopping you from understanding all that I wrote in this post and the previous one.

The pix tell us where the Amazons sit
These aren’t fake photos. They show natives paddling the Amazon from every possible solo position in the hull. They don’t tell us why or what the circumstances are that make them shift.

I’d be interested in learning from tdaniel what the size and weight of the bow paddled canoes are. And what the rocker and waterline shapes are. Finally, I’d like to know if those upstream bow paddlers stayed on the same side with their paddles or did the high tempo São Paulo switch.

I wish some more polers would chime in. I’m not a poler but I have always understood it to be axiomatic that you pole bow light up any kind of current, no matter whether there are rocks or not. Maybe I’m wrong.

I’ll give my answers to my experiments in another post.

Serge Corbin vs. the Amazons
What’s the difference if any between these two scenarios.

1. You paddle up the smooth water Amazon at a speed of 4 mph against a current that is flowing at 2 mph. Therefore, the water is streaming by your hull at 6 mph.

2. You paddle in no-current water at 6 mph, as marathon racers commonly do. Therefore the water is streaming by your hull at 6 mph.

In scenario 2, moving at 6 mph through still water, is it is more efficient to sit in the bow of your canoe? I believe Serge Corbin and every marathon racer would say no.

Would Serge move to the bow in scenario 1?

Understand completely.
My description of “no forward thrust” was, as you point out, technically incorrect. The point was that the boat is simply held in place and not pushed forward. In a moderate current, you could do the same with a paddle - and yes, the forces applied would be different because the paddle will be off to the side and not directly behind the boat.

But the fact remains that the time between pole plants, the boat will react to the current the same as it does between paddle strokes. The difference is that the paddle stroke itself is not as mechanically rigid as the pole plant. The boat will react differently to the paddle or the pole (but only by a matter of degree, according to the force applied) - but the water passing under the boat or pushing against the boat is the same.

For the sake of the drill I mentioned above, in an easy current, it takes very little force to hold position with a pole on the bottom. It takes more energy to do the same with a paddle - but it can still be accomplished, and the hull/current interaction is the same.

Off-topic - but I find the single biggest difference between poling and paddling in mild current (other than conservation of energy) is that the poler can see farther and plan earlier. It’s an advantage that gives the poler a leg-up on learning to read the current and respond.

Lying photos - not faked.
Didn’t mean to suggest that the photos are faked - just that they don’t necessarily portray what the viewer might perceive. There’s just not enough information there - as you note. I do’t know how they teach journalism these days - but in my day, that was an important point to be learned.

Only if it would help him win…
…and I think that makes your point.

Axioms
"I have always understood it to be axiomatic that you pole bow light up any kind of current, no matter whether there are rocks or not. Maybe I’m wrong."

There is a tendency to do that and it often can’t be avoided (especially in an empty symmetrical boat), given that the yoke is in the center of the boat - but it isn’t always the case. In light current on flat water, (I perceive) it is often more efficient to keep the trim as near flat as possible - just as on a lake. You still have to make adjustments for differential current, but that can be done with pole thrust, leverage, ruddering, or edging the boat a little.

I’m no expert, and maybe someone with more poling experience will chime it - but I often change trim from bow-light to, well…less bow light, when climbing a drop. I hop forward just as I crest the lip to get the bow back down and even out the trim for better efficiency.

Ignore all this over anaysis
It is probably interesting to those who are doing it. But you are perfectly capable of learning to paddle upstream without making it an excruciating intellectual exercise. You need practice, help from a competent assistant, and a decent boat. The decent boat is important since a cheap rec boat will make the task more difficult. A competent assistant is important since you will need feedback to help you correct problems and help for you to get to shore when you capsize. It does not take long for trying in safe circumstances to result in learning. And there is no quiz at the end.

I’ll share what I remember

Doc, should he go bow light or heavy
You can just answer without any analysis.

Of course, analysis may not be necessary in a kayak where you can’t shift your paddling position and you have a double blade.

But just for the heck of it: Is bow light or heavy better upstream?

Every day is a quiz! ;-D
True enough - getting on the water with an accomplished paddler as a guide will gradually make all this make sense without even thinking about it. Enough info here for the OP to go out and apply it in any manner he chooses and learn for himself what works.

bow/stern balanced is obviously better
And obviously you can imagine situations where out of balance is extreme (2 cases of beer in the stern???). But for likely and reasonable circumstances and appropriate boats this seems an esoteric problem that has little consequence for the typical paddler. It is much more important to learn paddling skills that enable you to handle what you are likely to encounter.

Even more piXX of Amazon Freestyle
These paddlers all all over the hull, just like Karen Knight in her thwartless Flashfire, but they are definitely sitting in the bow a lot. I think they know something we don’t.

http://s3.amazonaws.com/mongabay/colombia/600/colombia_1161.jpg

http://www.naturegraphics.net/pb8143w%20Fisherman%20in%20canoe.jpg

http://www.solarnavigator.net/images/Canoe_dugout_Rennell_Island_Lagoon_Solomon_Islands.jpg

http://www.erroluys.com/images/AmazonCanoe1.jpg

http://images.travelpod.com/tw_slides/ta00/f46/854/canoe-on-the-amazon-river-n11-belem.jpg

And this one is for tdaniel’s 1986 memory book:

It’s getting late - isn’t it?
I was watching the Karen Knight video again and thinking…

Paddling from the bow gives one a pretty short reach to both sides of the boat. I notice that she has no trouble making the boat point in her desired direction - although speed is naturally reduced. Leverage (or lack thereof, in the case of the boat behind her) is definitely working in her favor.

In the case of the Amazon canoes, it also puts the paddlers very close to the water. I can imagine a few good reasons to go that way. Are they fishing with hand-lines? (Pretty likely, I think) Gathering food stuffs from the banks? Keeping the wind in their faces?

It seems it would work on a wide and flat river, but maybe not so much on a smaller and meandering stream with current - or anywhere that speed or efficiency are in order. Looks like a skill worth pursuing in the canoe and adding to the repertoire - and once again, the freestyle practitioners are onto something.

Anyway - it doesn’t really relate to the OP in his kayak. Even if he was able to weight the bow to even some degree, paddling from where he must sit wouldn’t give the same leverage for control or the same balance. I’m still relating this to backferrying in a tandem canoe, with my lighter-than-me partner in front. The leverage is there to control the upstream end, but it wouldn’t be if I paddle from near the middle with the same trim and orientation.

It’s all interesting though, and makes me a bit more curious about the lifestyle of those river people. I have to admit, I’m interested in trying the method. I’ll have to remove the end bags and cages…

It’s not too late nor about upstream
I think the OP got a lot of practical advice in the first half of the thread, so I’m not going to feel guilty about this this Amazon issue.

I don’t think sitting in the bow is specifically an upstream technique. The lying photos clearly suggest that they paddle this way in all waters and even when still. I wouldn’t be surprised if they learn that technique as children and use it in all sorts of conditions.

In fact, here’s a picture of a very young Amazon girl paddling from the bow. She’s too small to sit in the center and probably doesn’t know how to correct. My daughter used to do the very same thing in my Explorer at her age. She just naturally figured out she could make the canoe go straight from up there.

http://www.flickr.com/photos/85941395@N00/398326621/

Why do they continue to bow position as adults? Not sure, but I suspect it’s a combination of having to expend the least stroke effort on yaw correction plus having a loose stern for maneuverability. They are willing to sacrifice speed for these attributes. They also have to learn a lot of balance.

They must specialize their canoe shapes for this intended posture. The canoes have little freeboard and seem to have up-swept bows with lots of flare. This could both help stability and reduce the bow-plow resistance of a bow down trim.

Yep - all that.
I suspect there’s some practical value in sitting up front too. The fishing/gathering lifestyle may have something to do with it.

The “late” remark was a veiled comment on the, um, XX photo.

Hunting/gathering and heeling
Some last thoughts before I forget them.

Yes, their lifestyle probably doesn’t require them to go fast or far. They don’t need to go out in wind or waves or rapids.

I suspect the boats have very little primary or secondary stability. Along with the lack of freeboard, no one is going to paddle these things Canadian style from the middle, nor are they going to heel these tender things for turns.

The bow might be as stable a place as any, and the down pitch surely facilitates turning these logs while not having to lean or heel. Probably helps eddy turning into the bank and around bends.

You are to be commended for wanting