Dumb Idea? Drift Sock for Downstream Propulsion?

[boy&hisdogs]

I was wondering if one could use a drift sock to pull a boat downstream. Think of it like a sail but it it catches water instead of wind. Would this work like I imagine it working?

I'm in no rush to actually try this, I was just curious what you all think.

 

[Gamma1214]

While it might work (somewhat), it sounds like a great way to create an entanglement problem and/or get hung up on rocks without any advantage gained. Even in the swiftest current, it's not terribly hard to match or exceed drift speed by paddling.

Hard pass IMO

 

[Alan Gage]

I can't see that being anything but a mess.

The canoe by itself will float downstream the same speed as the current so the sock won't pull you any faster. Simply holding a paddle in the water will have the same effect as the drift sock.

Most likely you'd end up with a drift sock tangled in some underwater debris which you would then be tethered to. If there was any downstream breeze, or you made any paddle stroke whatsoever you would quickly overtake the sock.

Alan

 

[Chip]

The boat floats along on the current, so the drift sock won’t add anything, unless there is big wind pushing the boat upstream. But most rivers don’t go straight so a headwind becomes a tailwind around the bend. Mostly, the drift won’t help and presents entanglement risks. I’m with Gamma, bad idea.

 

[ScottS]

It's an invention that did not need to be invented, by someone who doesn't know what they are doing.

 

[SouthernKevlar]

Maybe you could deploy the sock behind you and use it to slow you down; think of it as compression braking for a canoe with an over-enthusiastic paddler. This idea might also be good as a training aid for an additional workout leading up to marathon season.

 

[WonderMonkey]

I think it's a clever idea. I don't think it will work out due to the possible tangles and resulting danger, but maybe in the ideal situation, some speed could be picked up. Sure, you could paddle faster without using it, but then again, would that be clever? No. But using a drift sock on a stretch before getting tangled up would be nifty.

 

[Alan Gage]

I think it's a clever idea. I don't think it will work out due to the possible tangles and resulting danger, but maybe in the ideal situation, some speed could be picked up. Sure, you could paddle faster without using it, but then again, would that be clever? No. But using a drift sock on a stretch before getting tangled up would be nifty.

I bet if you used two of them you could go twice as fast.

Alan

 

[Nick Pending]

I bet if you used two of them you could go twice as fast.

Alan

Alan! Just make it twice as big! < Huge GRIN >

 

[Nick Pending]

Boy'ndogs,
Not trying to belittle your idea with my previous post, but I seem to remember seeing it proposed before. Maybe it was on another site? Not sure. Anyway, it wouldn't work in most of the rivers I've paddled, which are mainly small, some of them tending to meander some. I could see it working at least marginally, maybe even well, in a large river like the Yukon or Mackenzie, especially if there was an upstream breeze or wind blowing. Rivers like that would have much wider currents rather than the narrow and sometimes opposing or splitting ones I get in little streams, or even big streams at low water. If employed, you'd have to be very wary of it catching a deadhead or strainer or rock or whatever. Could quickly cause a capsize. Some float or arrangement to keep the chute relatively near the surface would help, but not negate such problems.

 

[ppine]

Dumb idea because it won;t work and may be dangerous.

 

[Glenn MacGrady]

Late to this thread, which I don't quite understand. Is this sock supposed to be in front of the canoe or behind it?

 

[boy&hisdogs]

Late to this thread, which I don't quite understand. Is this sock supposed to be in front of the canoe or behind it?

The idea was that it would be out front so it's pulling the boat forward like a kite.

I know it's silly, it was just a thought experiment.

 

[Glenn MacGrady]

The idea was that it would be out front so it's pulling the boat forward like a kite.

I know it's silly, it was just a thought experiment.

I don't think the idea is practical, for entanglement and other reasons, but it's an interesting thought experiment.

As a theoretical matter, some might say that anything that is drifting in current, like a boat or sock, will drift precisely at the same speed as the current. After all, that's sort of the definition of "drifting."

However, that's not my canoeing experience. In swift current rivers, I have always noticed that drifting leaves and small sticks on the surface would slowly pass my drifting canoe. I even tested that by putting some small floating items from my canoe next to me in the water. They would begin to go faster than my drifting canoe.

Why?

I assume it's because of some combination of greater air friction and water friction against my drifting canoe than the against the drifting leaves and sticks. As a matter of river dynamics, the current in rivers flows at different speeds in different vertical layers. The layer closest to the bottom is the slowest because of friction between the water and the ground. Each higher up layer flows a bit faster until the very top layer, which flows a bit slower than the one below because of friction between the surface water and the air. So, the water immediately below the surface is the fastest, but then the water gets slower and slower until the bottom. I don't have any idea how thick these various current layers are or, stated differently, how steep the current gradient differential is.

My guess is that my canoe + me offers prodigiously more air friction than the surface layer of the water. I also speculate that the bottom of my canoe might be in slower water than the very surface, which creates more water friction than the leaf or stick is experiencing. Therefore, my canoe + me drifts very slightly slower than a small object on the surface because of some combination of increased air and water friction.

In any event, I suspect the efficacy of the frontal drift sock or drift pail will depend on how deep the sock/pail is and how much water friction it encounters vs. the air and water friction on the canoe + me. I suspect the difference will be trivial and that one wouldn't notice any significant pulling effect from the frontal drift mechanism, especially in slow or moderate current.

 

[yknpdlr]

Not only are there different velocities in different vertical layers, but also in horizontal slices. I learned a lot during the Yukon River races. We could be moving nicely along with current and paddling our hearts out, but there were times and places in that broad massively moving volume of water where if we just shifted by as little as a boat length or less left or right from our present track, we often could gain (or lose) 2mph or even more. Much more difference if close to shore of course, but even in the wide broad open center flow the effect was notable. From my bow seat I could often watch the surface for tell tale signs and ripples that gave away a change in current speed. So many other observations also made significant differences in our efficient down river progress.

 

[recped]

You can easily have an eddy in the middle of the river if there is a big bump in the river bottom that would send the current sideways

 

[yknpdlr]

You can easily have an eddy in the middle of the river if there is a big bump in the river bottom that would send the current sideways

Of course this is true, but what I refer to on the flat wide Yukon was common in deep water areas of the river that were a half mile wide or more with no indication of any "big bump on the river bottom" and the effect of faster side currents lasted for many hundreds of yards before we tested side slipping sideways again to get into another faster current as indicated on the GPS. I do know from speaking with experienced boaters on the river that there are multi level currents that occasionally collide, causing visible upwelling "boils" of water where surface currents may also change.

When the rifver current approaches within as far as a half mile upstream from an upcoming island, the fast current begins to noticeably split to go on both sides. Get yourself on the longer distance side that you don't want to be on and you wil pay heck to paddle hard enough to cross over to get to the other side of the island with distance and current you really want to be on before being swept away wrong and long.

 

[boy&hisdogs]

So here's what I'm thinking:

A canoe only rides a few inches in the water, but sticks a few feet up in the air (with paddler) so there is a significant amount of air resistance compared to the small portion of the canoe in the water.

A symmetrical canoe is equally streamlined from the front as it is from the back so it's not being pushed quite as hard as something like a square stern boat or random floating object

A canoe would be be up top getting pushed around by the wind (head or cross winds), irregularities in the surface, etc where the sock would be fully submerged in the current.


Imagine it's in big water, like the Columbia river, with wind, a slightly choppy surface, and a deep, strong current.

Again, it's not practical, but interesting.

 

[Nick Pending]

So here's what I'm thinking:

A canoe only rides a few inches in the water, but sticks a few feet up in the air (with paddler) so there is a significant amount of air resistance compared to the small portion of the canoe in the water.

A symmetrical canoe is equally streamlined from the front as it is from the back so it's not being pushed quite as hard as something like a square stern boat or random floating object

A canoe would be be up top getting pushed around by the wind (head or cross winds), irregularities in the surface, etc where the sock would be fully submerged in the current.


Imagine it's in big water, like the Columbia river, with wind, a slightly choppy surface, and a deep, strong current.

Again, it's not practical, but interesting.

That's correct, as I allude to in my post above. It could be especially effective in an upstream wind, also noted above. The trouble is, if there's very little breeze, it's very easy to paddle faster than the current as the canoe is already going almost current speed. It doesn't take much effort at all to paddle right past that sock. That makes the whole idea not worth much more than your thought experiment, or at least in my opinion. And the danger factor is in my and others' opinions as you can read above very real, so I'd leave it as a thought experiment. The Columbia is a big river and can kill your butt. And those of the dogs.

 

[Gamma1214]

A safer and more predictable experiment is dragging a short length of chain to slow you (ie: for fishing). Just be sure to tie it in a manner that a quick tug cuts it free (a float on the rope so it can be retrieved is also a great idea)