Ever have a downriver wind push you up river?

[alsg]

Normally a downstream wind pushes you downstream. Ever had a downstream wind push you upstream? Seems to defy physics, but that was my experience today.

This was my typical Sunday paddle on the Potomac with the Washington, DC Canoe Cruisers Association. I've made this run dozens of times. Some of the more experienced folks have done it hundreds. We put in on a tributary of the Potomac and cross the Potomac on a fairly flat section but heading down river toward the entrance to the so-called GW canal -- a class II run along the opposite shore. By the compass, the desired path of travel to get to the entrance of the GW canal is ESE and it's 3300 feet on a beeline to the entrance to the GW canal.

A brisk and stead wind was up around 15 mph with sustained gusts 20-25 mph. Wind direction was from the WSW so the wind was coming across our desired path so that our desired path and the wind direction formed an almost perfect X. Waves were about 15"-18". The wind and the waves made it extremely difficult to progresss downstream or even turn our boats downstream. It was sort of like a wind and wave driven involuntary front ferry that you just couldn't fight. Both open boaters and kayakers alike (including several Class IV paddlers and one Class V paddler) found ourselves being pulled progressively UPstream. It was not until we were in the lee of the opposite shore that we could turn our canoes/kayaks downstream and make progress downstream, albeit with great difficulty.

Anyone else ever experienced anything like this?

 

[Glenn MacGrady]

Not sure I quite understand this, but it's not happened to me. Wind, almost always, blows.

I once was paddling downstream on a slow river in Connecticut and all of a sudden I realized I was going upstream. I stopped, in Rod Serling puzzlement. How could a river change its direction of flow?

I backtracked downstream on the new upstream and finally discovered I had inadvertently padded into a tributary at an intersection, which had the overall appearance of the being the main river.

 

[alsg]

Glenn, maybe this will help. On the map below, the orange line is the downstream direction of the current. The yellow line represents the desired direction of travel. The red line represents the wind direction. We were pushed in the opposite direction of the orange line.

 

[Glenn MacGrady]

That's about how I understood it, but I don't understand it. I can see the wind creating weird wave geometries. Wind not only blows; it apparently also sucks.

 

[MrPoling]

Could it be the wind shifted the current? Maybe creating an upstream flow on one side? Basically an eddy?

Whatever the reason, I believe you. I've seen wind and water do things that don't make sense.

 

[JohnSand]

I used to sail a sloop up and down a narrow canal. There are houses and trees along it which would obstruct the wind or change its direction. On one occasion I remember the top of the sail billowing one way while the lower portion filled the other. Sailing that same boat under the Brooklyn Bridge I experienced wind blowing straight down, causing the boat to turn slow circles.

 

[Tsuga8]

Along the same lines, I think the answer is eddies in wind and water. Several times I've been paddling twisty, winding creeks in a wind, where following the creek leads the boat through all points of the compass as it twists and turns. You'd think you'd either get wind following the channel, either upstream or downstream, or keeping overall prevailing direction, but it seems to defy both of those and change unpredictably. As JohnSand says, I think tree lines, topography etc all play havoc with the wind, and the eddies and swirls are noticeable but hard to make sense of. They might also form and dissipate as the wind gusts and dies back.

 

[Glenn MacGrady]

In reading Michael Pitt's trip report on the Thelon River, I just came across this example of wind, wave and current confusion:

Today, we paddled around a bend toward some trees growing in the centre of the channel. As we aligned the boat with the current to drift by the small islands, we seemed to be slipping backwards. The strong head winds and waves affected our ability to read the current properly. After a few more attempts, we realized that we were actually paddling up stream on a side channel of the Thelon!

 

[alsg]

In reading Michael Pitt's trip report on the Thelon River, I just came across this example of wind, wave and current confusion:

Thanks, Glenn, et al. But the factors discussed by Paddling Pitt, Tsuga8 and John Sands just weren't part of the equation for my group. The wind was from a constant direction, at a slight angle but basically heading straight down stream. It's a wide open section of the Potomac. No islands where we were. No twisty switch-back creek. No squirrely currents. No confusing side channels. We didn't get lost or turned around. As I said, I've personally paddled it dozens of times and others on the trip had paddled it hundreds. We absolutely knew where we were but couldn't point our boats down stream for any length of time and got pushed/sucked upstream. We had good reference points on the shore (pretty hard to miss the giant flag pole on the Trump golf course there). It's a mystery but I'm sure wind and waves are the culprits.

 

[Glenn MacGrady]

Thanks, Glenn, et al. But the factors discussed by Paddling Pitt, Tsuga8 and John Sands just weren't part of the equation for my group.

Yes, I know, but since your mysterious wind/wave phenomenon on the Potomac seems so alien, others including me are just posting about other weird experiences. Were you paddling towards Washington, D.C.? Maybe it had to do with all the hot air emanating therefrom.

 

[Ralph]

A number of years ago I recall seeing a video of Omer Stringer using the wind to help him paddle upwind. If I recall, he tilted the canoe slightly away from the wind and the wind created an eddy in the canoe and that eddy "sucked" the canoe upwind. Perhaps that's what was happening in your case. You were cutting across the current, tilting slightly downstream so that the upstream gunnel was higher than the downstream gunnel. Maybe that created the same effect that Omer Stringer was using???
I tried for a few minutes to find the video with no success.

 

[alsg]

A number of years ago I recall seeing a video of Omer Stringer using the wind to help him paddle upwind. If I recall, he tilted the canoe slightly away from the wind and the wind created an eddy in the canoe and that eddy "sucked" the canoe upwind. Perhaps that's what was happening in your case. You were cutting across the current, tilting slightly downstream so that the upstream gunnel was higher than the downstream gunnel. Maybe that created the same effect that Omer Stringer was using???
I tried for a few minutes to find the video with no success.

It happened to the kayakers, too.

 

[Glenn MacGrady]

he tilted the canoe slightly away from the wind and the wind created an eddy in the canoe and that eddy "sucked" the canoe upwind.

I'm interested in the physics of this, if true.

I don't see how the so-called eddy on the downward side could propel the canoe upwind unless the air pressure on the downwind side of the hull was greater than the air pressure on the upwind side. If this actually happens, maybe it's not an eddy on the downwind side so much as it is Bernoulli's principle and the Coanda effect operating to reduce air pressure on the curved surface of the upwind side of the tilted hull, thereby generating "lift" in the direction of the upwind side against the water current—much like the curved top of an airplane wing generates lift against gravity.

It happened to the kayakers, too.

If my speculative physics is true, the same lift effects could operate on an upwind tilted kayak hull.

Maybe. Where is Richard Feynman when we need him!

 

[Ralph]

I hope a physicist or two chime in. It would also be interesting to have a paddler try Omer's technique and report back.

 

[alsg]

I hope a physicist or two chime in. It would also be interesting to have a paddler try Omer's technique and report back.

I have asked a physicist (professor at Georgetown whom I've know 50+ years) and he's a bit stumped. There was also a former NASA engineer on the trip. He's stumped too.

 

[Ralph]

I am a long way from being any kind of physicist so it's very interesting to me that those people are stumped. I've been looking for the Omer Stringer video but can't find it. There are a couple of short clips of his videos but nothing about what I think I saw.

 

[Ralph]

I am starting to doubt myself. Did I really see a video of someone being "sucked" upwind in a canoe or was I just imagining that it could happen?
I've become somewhat obsessed with finding the video that I think I saw. It was relatively easy to find the clips of Omer Stringer videos but finding the full-length versions has been more difficult. I did find the full-length version of Paddling Out of Peril at:

http://www.tamakwaarchive.ca/playvideo.php?passfile=video10/PaddlePeril.mp4&linknum=1957

but the scene I am searching for was not on that film. I'm still trying to find the full-length version of Paddle and Portage but no luck so far.
Anyone know where I can find it?
Regardless of whether I find it or not, the next time I get out paddling when there is a reasonably strong wind, I'm going to test the theory.

 

[lowangle al]

At my place in Anchorage the prevailing winds come down the mountain, but it blows my baker tent among other things, up the mountain. I think wind currents act like air currents and you were probably in an eddy. I think the "eddy line" is called wind sheer. Maybe a pilot will chime in.

 

[ppine]

Sure. In slack water the wind can easily push a canoe upstream without propulsion. In the West we paddle a lot canyons. The normal diurnal cycle is down wind at night and upwind during the day with surface heating. We normally get on the river early and quit in the afternoon, often because of the wind. Rafts and drift boats are affected by the wind more due to the surface area above the water.

I remember paddling the lower Colorado River in Feb. We had strong up canyon winds but lots of current under us. It made for some really interesting paddling. Lots of boils and whirlpools and being shoved around. I miss rivers like that.

 

[lowangle al]

Getting pushed upstream by an upstream wind is pretty easy to visualize. The OP in this thread was pushed upstream by a downstream wind. Much more mysterious.