Technique to paddle against the current.

-- Last Updated: Mar-13-12 12:02 AM EST --

I am in physic field. For long, long time it was always puzzling me if somehow we, I can use the flow of the river to drive my boat against its course as if one can sail into the wind (In physic water and air are both fluid).

I have post several configurations to help one to do so. One of its is as simple as just having a foil shape 'paddle' in a right angle and by itself it will push your boat, canoe, . . . forward, against the current without using your force except to keep the 'paddle' in place, using the same principle of the sailing boat.

The location is:

Happy paddling


For easy I state my other two video

One to show the setup:

And the other to show that by changing the angle one can move up/down etc . . .

Further investigation

– Last Updated: Mar-10-12 9:34 AM EST –

With no sound on my computer (I know, I really need to get that fixed someday), I'm not totally sure what's going on, but I assume you are saying the current is from left to right? Is there some effect going on that you have to "start" the boat (it would be the boat's on stationary momentum in your model), or is there some complex flow going on in that very confined chute? You see, I've noticed that progressing in very shallow water or confined shallows sets up a current that's opposite in direction from the boat, immediately around the hull, but of course the energy that causes that flow comes from my own paddle power, and I only see it in extremely tiny channels where the boat barely fits.

You see, in sailing, there are two contradictory forces at work against the boat and sail. The resistance of water keeps the boat AND SAIL properly aligned with the wind, and once the wind creates a diagonal force with a slight forward component to the boat, the boat's resistance to sideways movement within the water redirects that force to provide forward progress against the wind (same thing that happens when ice skating). Without the interaction of wind AND water on sail and hull, tacking would not be possible. Imagine trying to make a hot-air balloon shaped in such a way that it would "drift upwind" - you NEED two unrelated forces (forces not part of the same single system) to make it happen, so you see why I am pondering what's going on here. It's easy to imagine doing such a thing with current IF there were another force to latch onto (like poking a pole against the bottom, sliding along on cables stretched above the river, etc.), something other than the water itself, to provide that same "tacking like a sailboat" action, but using the water only to drive forward seems too much like getting energy from nothing.

SO, what happens in a real-world situation where the flow is not so tightly confined? Try it in a very large chute with a greater amount of laminar flow and see what happens. Set it in a very slow-flowing creek that's a foot or more deep and see what happens.

Again, my ponderings about what's going on here might be more relevant if I could have heard the narration.

I hope Carldelo reports in.

Energy from nothing?

– Last Updated: Mar-10-12 9:36 AM EST –

No it's not.

I utilizes the kinetic power of the current to drive the boat forward. The research is a by product of my other project when i build a floating dock to house a water turbine. I need to utilize that force to pull the dock out of the bank and also to lessen the tension on the cable.

A Google on the "Lift Vs Drag force" on a foil, airfoil will give you much more info.

My set up is using a water hose running from left to drive, You may see some from of turbulence in the debris when the water hits the wall at the far right. And once the boat pass that area it actually picks up the speed to run faster. (The video has no sound).

It is also easy for one to build a first configuration (foil boat) and test it in your bathtub. (1) Partially fill it, (2) put the boat in the direction to move away from the drain, (3) Open the drain plug; You will see it move away from the from the drain plug.

Happy paddling


– Last Updated: Mar-10-12 9:37 AM EST –

So there IS an energy input in the form of a confined jet of water. So tell me what happens when you place this model "boat" in a creek? In the real world, you'd need to hire the local fire department to set up a high-speed jet just upstream of your location at all times, right? My point is you are apparently not getting a free ride.

On a creek?

– Last Updated: Mar-10-12 9:52 AM EST –

It does as expected (Not on the actual creek but from the draining ditch . . . . after the rain)

Actually in physic the kinetic water is about 1000 times of the air, So it does not requires a high speed of jet stream as you said. It affect as soon as there is the flow.

I have spent countless hours of watching the fish, swimming against or stay put in the current by just bending its body to form a foil shape.

Happy paddling

What’s expected?

– Last Updated: Mar-10-12 9:52 AM EST –

What I expect, when an outside energy force is not causing a portion of the water in the creek to move more rapidly than natural gravity-driven flow is that the boat would drift with the current, not against it. If that's not what happens, I think it would be cool to see video of the model boat drifting upstream in a creek while bubbles and floating debris go past the boat, with the current. I don't envision a confined jet of water that's independent of the main body of water carrying the boat (water set in motion by an outside energy source) to represent a real-world situation.

Sorry if I expect such a phenomenon to be properly explained, but I'm a detail-oriented guy who likes to see reasons.

The model moves against the flow.

For Skeptic.
It only take me 10’ with a band saw a piece of 2 x 4 + a small piece of aluminum from a soda can to build as foil boat to see for yourself.

There is an interesting observation on that model. It only goes against the current only.

A google on “lift vs drag” force on “airfoil” + “sailing” will give one much more information and it is independent from the third parties too

Happy paddling.

A boatload of crap -:wink:

– Last Updated: Mar-10-12 10:12 AM EST –

You can't go against the current without additional propulsion. Period.

If there is a back-current, yes you can utilize that. If you look carefully at your own video you will probably notice the turbulence and the debree in the water that actually floats in the direction your boat is floating. That's what is propulsing your models. Your setup is flawed for what you want to prove.

Think of a bird staying in one place or planing against the wind - that happens for one simple reason: it has additional propulsion even though it is not moving its foils, er... wings: gravity. The bird will eventually fall down because to move itself forward it glides down. If it appears it does not fall down, then it is benefitting from updrafts to compensate for the dow-ward force of the gravity - so again additinoal propulsion.

Fish?!? Fish does not simply create foil shape. They create propulsive force with teir bodies and tails as they bend from left to right. It is not the current against the foil shape magically propelling them upriver...

You claim to be a physics major - use thy brain and formulae to help you figure it out.

Sailing against the wind is also 100% impossible. You can go at an angle to the wind, but you cannot sail straight against the wind.

I hope you are not trying to prove one can go straight against the current with no added propulsion... Things like that were popular in the middle ages, but have lost their appeal since -;)

I like it. River banks are not as
confined as the test fixture but the principles make sense. Flow is greater than on an actual river and river flows constantly vary. And then there’s cross currents. But even with all of that, tweeking by a skillful operator could get the boat moving. I’m in if you need a volunteer.

Middle age?

– Last Updated: Mar-10-12 10:56 AM EST –

"Things like that were popular in the middle ages, but have lost their appeal since. . ."

The foil technology is only developed with the invention of the air plane. Since then we truly understand the principle of sailing into the wind (with and angle, from high school that angle has two vectors, one goes into the wind and the other goes sideways).

Understanding River flow…better

– Last Updated: Mar-10-12 2:15 PM EST –

Paddling upstream is done by many to avoid the whole
issue of shuttling boats, gear, and personnel.

Something to keep in mind

Helicoidal Flow : a corkscrew movement in a meander
bend of a creek, stream, river.
This is what moves material from the Outside of a bend
and deposits it on the Inside of the next bend.

To learn more:


– Last Updated: Mar-10-12 2:23 PM EST –

Ah, pity the legions of foolish salmon, expending all that energy over the millennia swimming upstream to spawn. Apparently all they needed do was arch their spines and they could have floated upstream on a raft of cradling vortices, saving their efforts for a few jumps up the waterfalls along the way….

I’ve watched the video, which is not enlightening, as it is unclear what the flow regime is. From the description above, it sounds like a closed trough with a hose in one end. I didn’t notice the floating debris that Kocho mentions, but on seeing it, it looks like there is a reverse current in the direction of the boat that is pulling it along. Also, GBG mentions the venturi effect, caused when an object moves through a restricted fluid channel - that appears to be at work as well. Without flow markers, the video is not helpful. The other experiments mentioned above are similarly flawed. A valid test would be to put a model in a flow channel and show that it can remain in place without aid, or demonstrate actual travel against a current in a real-world situation.

The underlying claim is that one can put an airfoil into a moving stream and generate a thrust force greater than the sum of the drag forces on both the airfoil and an attached hull. It’s difficult to see how that does not violate a couple of fundamental laws of physics. When flow goes around a body, it generates a resultant force vector. The physical source of this force is the pressure distribution around the body – the overall force is computed by integrating the pressure distribution over the surface area of the body. Because drag is non-zero in all real fluids (i.e. virtually all real fluids have non-zero viscosity), the resultant vector must have a component in the downstream direction (the “drag” vector). Depending on how well your airfoil is designed, the transverse component of the vector can be quite large (this is the “lift” vector, and points perpendicular to the flow direction). When these two components are summed, the resultant must point (at least somewhat) in the downstream direction. Progress directly upstream is not possible, as there is no component of force in that direction to make it happen. Getting back to the physical causes, traveling upstream would imply that there is a low-pressure region on the upstream side of the body, essentially sucking it upstream, which is not really reasonable.

Sailboats exploit the transverse lift (or horizontal thrust, if you prefer) to tack at an angle to the wind. This is also how wing paddles function, although it’s more complicated due to the additional motion of the paddle. In flying, the transverse lift vector is used to counteract the weight of the flyer. These points were made by GBG and Kocho above: to sail forward, one must tack off the wind, at least a little bit; to glide at constant height requires an upward component of the wind relative to the glider provided by some atmospheric feature (a ridge creating an updraft, a thermal, etc.).

The OP suggested more than once to look at explanations of how an airfoil works – it seems to me that Kocho and GBG are pretty well up to speed, and that he is the one who could use a brush-up:

“The foil technology is only developed with the invention of the air plane. Since then we truly understand the principle of sailing into the wind (with and angle, from high school that angle has two vectors, one goes into the wind and the other goes sideways).”

As discussed above, the drag component does not point into the wind, but rather downstream. I would also take issue with the statement that airfoil technology is a strictly modern invention. Airfoils have been around for millennia, in the shape of sails and in the cross section of Greenland paddles to name just two. The analysis is recent, but that doesn’t mean they haven’t been in use. I have a great deal of respect for the mechanical intuition and ingenuity of human beings – if there was a simple configuration that could propel a boat directly against a current, I think the Egyptians or Indians or some other technologically savvy early civilization would have figured it out.

I try to imagine flying a kite without a string, and it doesn’t really make sense. The propulsion idea presented appears to imply that one could design a kite that could fly without a string, which is truly a reductio ad absurdum. There is no free lunch.

Middle Ages & Vectors
(as opposed to middle-age) was a time when perpetual motion was a hot topic. That’s what I’m talking about.

I’m glad you mentioned vectors, wasn’t sure you’v reached that topic in school and now I 5hink you probably slept through it -:wink: Think about the force vector of the current. decompose it as much as you want to 2 vectors, their sum will not somehow magically become greater than the original vector. Don’t believe? Ask your professors… The only way you are going to overcome a force is by a force greater than it - you can’t make something from nothing…

Theoretical discussion
I do not intent to spur up theoretical discussions.

They are reproducible phenomena. At the moment it works on my models and does require some minimum water speed, depend on the model.

I do think it is applicable in the real world.


Happy paddling.


You invoked theory when you suggested that reading up on airfoil theory would enlighten your detractors. It appears you do not understand the phenomenon you report, and by suggesting we accept it without any theoretical basis you have vaulted directly to the realm of pseudo science. I suggest you read up on airfoil theory, preferably in an undergraduate level fluid mechanics textbook, rather than the internet. If you actually have a background in physics, that shouldn’t present a problem.


– Last Updated: Mar-10-12 7:01 PM EST –

I hope . . . . intent????

It is for the "great mind" to explain ??? the fact.

If one can not "understand" or the theory that can do not explain that fact then it is not applicable otherwise . . . nothing to say!

FYI: My first try was about 1975 and was on and off since then

Thanks for the link H2o

Perhaps Language Barrier?

– Last Updated: Mar-10-12 8:38 PM EST –

Yes, a properly placed foil shape can provide "lift" that can be more efficient than a "push" type. I read about some of your wind and current turbines and the basic idea is sound. Vertical wind generators do work. Foils work (competitive kayak paddlers use foil-shaped paddles for that reason). That's all fine.

However, here (and in your floating foil boat video) you seem to imply you can take the idea one step further. Are you trying to say that you can actually float directly against current (not at an angle but straight-up). Or that you can end-up further upriver from where you started without using any energy other than the current flowing against you??? This you can't do, unfortunately...

Your video does not show you can float against current. It shows a boat floating in one direction. These 2 are not the same, because there are forces at play that the camera does not capture. Make a kite without a string, as Carldelo says - that's the same principle you are trying to say is working in your model: if what you seem to be saying is true, people could just lift-off in a big-enough plane against the wind and go wherever they please with no energy needed whatsoever. Going faster than the wind's speed is something completely different and it is fairly easy to demonstrate and most people will understand easy enough. However, no one has been yet able to sail straight against the wind -;) Not without a motor in their yacht...

It's like saying, a skier can go uphill indefinitely if they carve a turn nicely... Sorry, can't do that...

Sound no go here
I don’t think the problem is on the viewing end. Nor is there enough info to really explain how this would actually work, let alone prove it.

Maybe if it was someone actually paddling…