I just have one last question reguarding all you Sea Lion Skeptics. . . If I were going to make up something to tell the Paddlewise community, why in the hell would I not have come up with something much more interesting to lie about? I promise you, if I ever try to "yank your chain" it will be about my circumnavigation of Greenland, or my solo crossing of the Pacific. . . not about the existance of an old $150.00 boat, that isn't even mine. Thx Rich. P.S. Just so you know , the mystery is solved. I haven't inspected it myself, but my friend tells me that there are two seems across the width of the boat just fore and aft of the seat indicating a home made stretch job. So yes, the 19ft Sea Lion does exist, and no it wasn't factory. -- Your favorite stores, helpful shopping tools and great gift ideas. Experience the convenience of buying online with Shop_at_Netscape! http://shopnow.netscape.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I have been thinking about the wing and wonder if the following makes sense. First a note on efficiency, which by definition is the amount of energy loss, between the place you put energy in and the place you take it out. If you imagine a perfectly vertical paddle, drawn straight back parallel to the boat, then, BETWEEN THE BLADE AND THE BOAT'S FORWARD MOTION, there is no energy loss at all, INDEPENDENT OF THE SHAPE OF THE BLADE. (100% efficiency.) This is because all the work you do on the paddle goes into moving the boat forward. The paddle could be square, or have holes in it and efficiency is still 100%. The paddle is just generating drag and changing the drag coefficient has no effect energy loss between the blade and forward motion. However, it can have a great effect on efficiency between the energy the paddler expends and the energy transferred to the boat. This distinction of where the losses occur is crucial. In practice the paddle is not vertical, nor does it move straight back. The wing stroke uses arms that are essentially locked through the power phase, causing the paddle to naturally move outward as well as back, generating both lift and drag in the same direction. This reduces the energy loss between the energy expended by the paddler and that received by the boat. Changing the size of the wing blade, or length of the paddle changes the gear ratio, just as for the conventional paddle, and should be chosen for the best efficiency of the particular paddler and the particular distance/speed he is racing. The paddler is a motor, and like any motor, is most efficient at a particular speed, which is generally not the speed for maximum torque. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Friday, June 6, 2003, at 11:13 AM, Gerald Foodman wrote: > I have been thinking about the wing and wonder if the following makes > sense. > > First a note on efficiency, which by > definition is the amount of energy loss, between the place you put > energy in > and the place you take it out. If you imagine a perfectly vertical > paddle, > drawn straight back parallel to the boat, then, BETWEEN THE BLADE AND > THE > BOAT'S FORWARD MOTION, there is no energy loss at all, INDEPENDENT OF > THE > SHAPE OF THE BLADE. (100% efficiency.) This is because all the work > you do > on the paddle goes into moving the boat forward. The paddle could be > square, or have holes in it and efficiency is still 100%. The paddle > is > just generating drag and changing the drag coefficient has no effect > energy > loss between the blade and forward motion. You are mistaking drag (a force) for energy. While it is true that for every Newton or pound of force generated by the paddler a equal and opposite unit of force is applied to the paddle by the water. All the force generated by the paddle is indeed transfer to the boat to make it move. This does not mean that all the energy is transferred without loss. The surest way to verify this is to look at the water. If there is any sign that the water moves at all due to the paddle, you must assume that there has been energy added water by the paddle. Moving water indicates kinetic energy in the water that could have been kinetic energy for the kayak. If there is energy in the water from the paddle that could have gone towards moving the boat, you must assume that the paddle is not 100% efficient. There is no such thing as a 100% efficient paddle. This is true regardless of the orientation of the blade or its direction of motion. > > Changing the size of the wing blade, or length of the paddle changes > the > gear ratio, just as for the conventional paddle, and should be chosen > for > the best efficiency of the particular paddler and the particular > distance/speed he is racing. The paddler is a motor, and like any > motor, is > most efficient at a particular speed, which is generally not the speed > for > maximum torque. > Changing the size of the blade does not change the gear ratio. The "gear ratio" is only related to the length of the paddle. Changing the size of the blade changes the speed at which it moves through the water, in other words it changes its efficiency. This is more analogous to having a bicycle chain skip or jump on the gears or having the gear rotate slightly relative to the peddle. Changing the blade size does effect the perceived gear ratio because for a given cadence it will take less force, and for a given force it will require a higher cadence. There are good reasons why people don't use huge blades on their paddle, but everything else being equal, smaller blade area means lower efficiency. There are practical reasons like a paddle with 4' x 8' blades would be hard to fit in the car, would be heavy and would just be awkward to swing around. You need to be able to get a paddle in and out of the water fairly easily and the physical construction of humans place certain limits on what is practical and comfortable. And diminishing returns means that at some point the added efficiency just isn't worth the other problems which come with large size. The right balance of overall efficiency of the paddle and comfort for a given paddler will effect the optimum size for the paddler. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick wrote: > Changing the size of the blade does not change the gear ratio. The > "gear ratio" is only related to the length of the paddle. Changing the > size of the blade changes the speed at which it moves through the > water, in other words it changes its efficiency. This is more analogous > to having a bicycle chain skip or jump on the gears or having the gear > rotate slightly relative to the peddle. Changing the blade size does > effect the perceived gear ratio because for a given cadence it will > take less force, and for a given force it will require a higher cadence. Didn't we thrash this to death last year? ;-) There's a conceptual confusion between the notions of biomechanical efficiency (translating muscle power into propulsion), paddle "efficiency" (translating swept are into propulsion) and mechanical advantage (paddle as lever). I think I noted back then that the "efficiency" of coupling the paddle to the water does *not* equate to efficiency in converting muscle power to propulsion (biomechanical efficiency). Two different things. A small blade doesn't move as much water with each stroke as does a large blade, but at the same time, it doesn't require as much energy input to move through the water. So yes, enlarging the blade has the same end result as does lengthening the paddle: It increases *both* the energy in and propulsion out for a given swept area, even though it accomplishes it in a different way. And both are indeed similar to changing gears on the bike. Shrink the blade or shorten the arm, and you increase the rate to get the same propulsive force over time. And that brings us to biomechanical efficiency. By experimenting with the tradeoff between blade size/paddle length and rate, you can find the optimum combination for you to transfer maximum power *over time*. -- mike ------------------------- Michael Edelman medelman_at_ameritech.net http://www.foldingkayaks.org http://www.findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> And that brings us to biomechanical efficiency. By experimenting with > the tradeoff between blade size/paddle length and rate, you can find the > optimum combination for you to transfer maximum power *over time*. > > -- mike This seems to be sound advice, except for those of us who don't have easy access to a wide range of paddles with different lengths, blade size, shape, etc. In my household we have a) two short "recreational" paddles we bought with our Scramblers - one piece, unfeathered, heavy as all get out; b) a long (240cm?) $30 paddle from Campmor; and c) a long, large carbon fiber paddle from Whetstone. Based on that sample the Whetstone is wonderful and I like it very much. But now I want to buy a paddle for my wife. I'm 6'4", she's 5'8". I've never had a problem with repetitive stress injuries; she has fibromyalgia and often endures painful flareups of her hands, wrists, and forearms. I want to buy her a light paddle that places minimal stress on her body. However, she's also quite strong, and I don't want to buy her something too "wimpy" and have her wish she had something a little more powerful. I doubt if we'll be able to find a range of paddles to try; she's going to have a hard time fitting paddling into her busy life. I'm hoping we can find the perfect paddle based on people's advice and the research I can do, buy it, and go paddling. Therefore, I'm interested in all of these theoretical discussions about paddles, efficiency, etc., as well as their practical applications. Keep 'em coming. Anyone have any advice for my wife and I? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> But now I want to buy a paddle for my wife. I'm 6'4", she's 5'8". I've > never had a problem with repetitive stress injuries; she has fibromyalgia > and often endures painful flareups of her hands, wrists, and forearms. > > I want to buy her a light paddle that places minimal stress on her body. > However, she's also quite strong, and I don't want to buy her something too > "wimpy" and have her wish she had something a little more powerful. Gordon: I'm very happy with my carbon fiber AT (Adventure Technology) paddle. It's bent shaft, which I think is the most important feature for somebody with wrist or arm injuries. It's great for bracing and rolling. Very smooth in the water. I really like a short paddle - mine is 218, and I'd really prefer 216. I'm shorter than your wife (5'5") but I think you get more control with a shorter paddle. There web page is: http://www.atpaddle.com/ This ain't no "wimpy" paddle! Good luck, Dee *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Gordon Snapp wrote: > > But now I want to buy a paddle for my wife. I'm 6'4", she's 5'8". I've > never had a problem with repetitive stress injuries; she has fibromyalgia > and often endures painful flareups of her hands, wrists, and forearms. > > I want to buy her a light paddle that places minimal stress on her body. > However, she's also quite strong, and I don't want to buy her something too > "wimpy" and have her wish she had something a little more powerful. There's a high tech organic matrix material you should look at. It's called "wood." Cricket makes paddles from it. I love mine. -- Steve Cramer Athens, GA *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
"But now I want to buy a paddle for my wife. she has fibromyalgia and often endures painful flareups of her hands, wrists, and forearms. I want to buy her a light paddle that places minimal stress on her body. However, she's also quite strong, and I don't want to buy her something too "wimpy" and have her wish she had something a little more powerful." Hi all, Lots of great paddles out there, but I can tell you that I find myself coming back to my wooden Greenland paddle again and again. A couple of points about it worth mentioning, especially in regards to your query: 1. Paddle is by design unfeathered, thus no chance of rotational injuries from the necessary paddle twist of feathered ones. 2. Paddle is very light weight, and as there are no mass points on each end, the throw weight is very easy to manage. 3. I found it extremely easy to learn to paddle using it, no real learning curve to speak of. 4. I find it to be by far the easiest on my wrist and hands, yet if I want to move out, I can accelerate and move quickly using it, with no trouble (I hit 5.9 MPH today and held it for several minutes with no problem). 5. Because of it's design (it's basically an uncambered, high aspect ratio wing) how much effort you want to put into paddling it is up to you-- paddle a bit harder and with higher RPM if you're in a hurry, paddle with less force and lower RPM if you want to relax. (I know that sounds like any other paddle, but anyone who's tried a Greenland paddle will know what I mean by this.) Mine is a wooden Feathercraft (not sure who really makes it) but I know there are several good makers out there, as well as plenty of tutorials on how to make your own. I'm just not handy enough with woodworking tools, but it doesn't sound hard to make one for someone with a little more skill than I. OK, my 2 cents worth. OBTW, many Kayak shops will let you try different paddles on a sort of test drive basis, just ask around. R/ Kevin *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Kevin wrote: - > 1. Paddle is by design unfeathered, > thus no chance of rotational injuries > from the necessary paddle twist of > feathered ones. G'Day Kevin and Paddlewise, I'm grateful to a woman called Linda Lehman who showed us that it was unnecessary to use the 'wrist cocking' (paddle twist) even with a feathered paddle. Its awkward to start learning but well worth it. It would be good to see the idea of NOT rotating your wrist when paddling more widely advertised. All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 6 Jun 2003 at 17:21, Gordon Snapp wrote: > But now I want to buy a paddle for my wife. I'm 6'4", she's 5'8". > I've never had a problem with repetitive stress injuries; she has > fibromyalgia and often endures painful flareups of her hands, wrists, > and forearms. What little I know of fibromyalgia (based on a recent web search) suggests that a paddle design can neither cause nor reduce the pain. However, a good paddle can reduce the likelyhood of a problem that is unknown becoming a apparent, so getting a good one is probably a good idea. She'll want a short paddle, possibly shorter than many kayak shops would recommend. Around here, they still recommend 230-240 cm for me, but I paddle with a 220 and wish I'd got a 215. She'd want possibly a 210 or even 200 - kayak size will be a factor so try before you buy. It's only too short if she can't get it into the water with all her favourite strokes. A carbon fibre paddle is pricey, but she'd appreciate the light weight. Similarly, a bent shaft will put less stress on her wrists. I'd recommend a variable feather so she can find a feather angle that doesn't require a lot of wrist flex, unless she has a prior preference for unfeathered. The other option that I'd have to recommend is a Greenland style paddle. You can make one for about $20 out of a premium quality 2x4. This will produce a paddle that's a tad less efficient but easy on the body. When I go out for a long day's paddle with mine, I end up with sore muscles rather than sore joints. You can buy one, but they tend to be quite pricey. There's even a carbon fibre version from Superior Kayaks that's quite light ($$). Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Gerald Wrote: - >In practice the paddle is not vertical, >nor does it move straight back. The >wing stroke uses arms that are essentially >locked through the power phase, causing >the paddle to naturally move outward as >well as back, generating both lift and >drag in the same direction. This reduces >the energy loss between the energy expended >by the paddler and that received by the boat. Nick Shade wrote: - >Moving water indicates kinetic energy in the >water that could have been kinetic energy for >the kayak. G'Day Gerald, I'm guessing that a wing stroke is one in which the paddle is at a low angle to the water compared with the vertical or high angle often used when racing kayaks. When I paddle with a high angle, aiming to keep the paddle near the side of the boat throughout the stroke, it feels much less exhausting than using a low angle. This may have nothing to do with efficiency and be a biomechanical effect, due to optimal matching of muscle, tendons and skeleton to stroke. However, it might also be that the low angle stroke is moving water at right angles to the boat and dissipatng energy, in the water and in the human body, that is not associated with forward movement? Arguably a low angle stroke is less efficient than using a high angle. All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick Shade wrote: - >Moving water indicates kinetic energy in the >water that could have been kinetic energy for >the kayak. Not necessarily. Water moving in the opposite direction of the movement of the kayak indicates that energy was transferred to the kayak. We had a lot of discussion some time ago about votex shedding off the blade and how that contributes to the lift generated by the paddle. And so on. -- mike ------------------------- Michael Edelman medelman_at_ameritech.net http://www.foldingkayaks.org http://www.findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Friday, June 6, 2003, at 11:34 PM, Michael Edelman wrote: > Nick Shade wrote: - > >> Moving water indicates kinetic energy in the >> water that could have been kinetic energy for >> the kayak. > > Not necessarily. Water moving in the opposite direction of the > movement of the kayak indicates that energy was transferred to the > kayak. We had a lot of discussion some time ago about votex shedding > off the blade and how that contributes to the lift generated by the > paddle. And so on. Yes, absolutely. Any water motion is energy that in a 100% efficient system would have been kayak motion. In real life water motion is inevitable consequence of applying propulsive force against a fluid, but that does not mean it is not lost energy. Vortex shedding may add to lift, but the vortex is still lost energy. This not to say that a paddle that creates a vortex is not more efficient than one that somehow avoids making the vortex, but lost energy is lost energy regardless of the form it takes. 100% efficiency is only possible when pushing against an absolutely stiff object of infinite mass, for our purposes the solid ground of the earth is a reasonable approximation. Poling your kayak would be as close to 100% efficient as is possible. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick, If the paddle were to be drawn straight back with the blade normal to the velocity, then the force applied by the hand depends on CD, paddle area and velocity. The work done by the hand then also depends on CD, area and velocity. Now if you had two different paddles stroked identically, working at the same velocity, with the same product of CD and area, would they necessarily be equally efficient? Even though the flow pattern around each would be different. Jerry > > Nick Shade wrote: - > Yes, absolutely. Any water motion is energy that in a 100% efficient > system would have been kayak motion. In real life water motion is > inevitable consequence of applying propulsive force against a fluid, > but that does not mean it is not lost energy. Vortex shedding may add > to lift, but the vortex is still lost energy. This not to say that a > paddle that creates a vortex is not more efficient than one that > somehow avoids making the vortex, but lost energy is lost energy > regardless of the form it takes. 100% efficiency is only possible when > pushing against an absolutely stiff object of infinite mass, for our > purposes the solid ground of the earth is a reasonable approximation. > Poling your kayak would be as close to 100% efficient as is possible. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Work is defined as a change in energy. If you measure the work done by your hand and you have all the parameters of your paddle matched such that they multiply together right it is absolutely possible to make the work done by your hand match with substantially different paddles. But remember that the work done by your hand is not the same thing as the work done on your boat. Imagine paddling one boat in free water, while paddling another which is tied to shore. You should be able to make two paddle, one for the free boat and one for the tied boat which when you paddle feel the same. The one for the tied boat will probably be very small, so it doesn't feel that hard to pull when the boat isn't moving. You will be able to pull this paddle and your hand will be doing work, but no work will be done on the kayak because it is tied in place such that its energy can not change. With no change in energy there is no work done to it. All the work you are doing with your hand is going into the water. In an ideal system all the work you do with your hand would transfer directly into work done to the boat. In a real system some of the work is inevitably dumped into the water. The goal is to find a paddle and a technique which reduces the the amount of work done to the water so most of it can go to your boat. On Sunday, June 8, 2003, at 10:05 PM, Gerald Foodman wrote: > Nick, > If the paddle were to be drawn straight back with the blade normal to > the > velocity, then the force applied by the hand depends on CD, paddle > area and > velocity. The work done by the hand then also depends on CD, area and > velocity. Now if you had two different paddles stroked identically, > working > at the same velocity, with the same product of CD and area, would they > necessarily be equally efficient? Even though the flow pattern around > each > would be different. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick Shade wrote: - >>> Moving water indicates kinetic energy in the >>> water that could have been kinetic energy for >>> the kayak. > I replied: >> Not necessarily. Water moving in the opposite direction of the >> movement of the kayak indicates that energy was transferred to the >> kayak. We had a lot of discussion some time ago about votex shedding >> off the blade and how that contributes to the lift generated by the >> paddle. And so on. > Nick replied: > Yes, absolutely. Any water motion is energy that in a 100% efficient > system would have been kayak motion. In real life water motion is > inevitable consequence of applying propulsive force against a fluid, > but that does not mean it is not lost energy. Vortex shedding may add > to lift, but the vortex is still lost energy. This not to say that a > paddle that creates a vortex is not more efficient than one that > somehow avoids making the vortex, but lost energy is lost energy > regardless of the form it takes. 100% efficiency is only possible when > pushing against an absolutely stiff object of infinite mass, for our > purposes the solid ground of the earth is a reasonable approximation. > Poling your kayak would be as close to 100% efficient as is possible. You say "Any water motion is energy that in a 100% efficient system would have been kayak motion", but as you note, water in not a perfectly rigid medium. The only way you can generate motion with a paddle is to move water backwards. Water moving in the opposite direction to the kayak's travel indicates energy that was transferred to the kayak. Newton's second law. Vorticies don't necessarily indicate wasted energy either. We talk about vortices "shedding" but the vorticies indicate a low pressure zone behind the paddle which generates lift. If you had perfectly laminar flow around the paddle you'd have no lift, and hence no propulsion. -- mike ------------------------- Michael Edelman medelman_at_ameritech.net http://www.foldingkayaks.org http://www.findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Sunday, June 8, 2003, at 09:50 PM, Michael Edelman wrote: > Nick Shade wrote: - >>>> Moving water indicates kinetic energy in the >>>> water that could have been kinetic energy for >>>> the kayak. > I replied: >>> Not necessarily. Water moving in the opposite direction of the >>> movement of the kayak indicates that energy was transferred to the >>> kayak. We had a lot of discussion some time ago about votex shedding >>> off the blade and how that contributes to the lift generated by the >>> paddle. And so on. > Nick replied: >> Yes, absolutely. Any water motion is energy that in a 100% efficient >> system would have been kayak motion. In real life water motion is >> inevitable consequence of applying propulsive force against a fluid, >> but that does not mean it is not lost energy. Vortex shedding may add >> to lift, but the vortex is still lost energy. This not to say that a >> paddle that creates a vortex is not more efficient than one that >> somehow avoids making the vortex, but lost energy is lost energy >> regardless of the form it takes. 100% efficiency is only possible >> when pushing against an absolutely stiff object of infinite mass, for >> our purposes the solid ground of the earth is a reasonable >> approximation. Poling your kayak would be as close to 100% efficient >> as is possible. > > You say "Any water motion is energy that in a 100% efficient system > would have been kayak motion", but as you note, water in not a > perfectly rigid medium. The only way you can generate motion with a > paddle is to move water backwards. Water moving in the opposite > direction to the kayak's travel indicates energy that was transferred > to the kayak. Newton's second law. > > Vorticies don't necessarily indicate wasted energy either. We talk > about vortices "shedding" but the vorticies indicate a low pressure > zone behind the paddle which generates lift. If you had perfectly > laminar flow around the paddle you'd have no lift, and hence no > propulsion. You are confusing a "necessary" process with an "efficient" process. Consider the internal combustion engine. When you car engine is cold it runs inefficiently. It needs to heat up before it really runs well. But the biggest source of inefficiency in a car engine is the fact that much of the energy that is contained in the gas is turn into heat. The engine creates so much heat that you actually need a radiator to get rid of the excess. That heat is energy that could have made your car go farther or faster. However, if you were successful in keeping the engine stone cold it would never run as efficiently as it could. It is necessary for the efficient running of the engine that it heat up, and it is also true that the most efficient source of that heat is from the prior combustion of fuel in the engine, but that by-no-means implies that the heat the engine produces is not lost energy and thus inefficient. A source of inefficiency may be harnessed to improve efficiency. But that doesn't eliminate the inefficiency, it just limits it. It is inevitable and necessary that you move water to propel a boat. It is not a contradiction that the most efficient way to propel the boat has built in inefficiency. If you take a snap shot of the vortex system made by a paddle and analyze it you must see that there is energy in that vortex system due to the kinetic energy of the water. That energy had to come from somewhere. You and your breakfast of warm beer and cold pizza is the source of that energy. If you are creating energy systems outside of adding to the energy of the boat itself, those energy systems are inefficiencies. The goal is to minimize the non-kayak-forward-motion-energy-systems. The vortex contributes to creating a forward force on the kayak, it does this by expending a small amount of energy into the water. You improve efficiency by reducing the amount of energy expended to create that force. Just because it is necessary that you expend this energy does not mean it is not lost energy and thus a source of inefficiency. Some inefficiency is necessary, the goal is to limit it. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick Schade <nick_at_guillemot-kayaks.com> wrote: >> Work is defined as a change in energy. If you measure the work done by your hand and you have all the parameters of your paddle matched such that they multiply together right it is absolutely possible to make the work done by your hand match with substantially different paddles. But remember that the work done by your hand is not the same thing as the work done on your boat. >> Nick, a small correction: Classically, work is defined as the force applied multiplied by the distance through which the force is applied ( W = f x d), not a change in energy. The change in energy in the paddler arm/back system is not all directed at accomplishing work. Some goes into generating turbulence in the water ("vortices") which ultimately ends up heating up the water a bit. (The water at the bottom of Niagara Falls is warmer by a tiny fraction of a degree because of the "stirring" achieved by the fall and subsequent random mixing of the water.) Consequently, if one is interested in determining efficiency in the paddler/boat/water system, he/she has to be careful to delineate what is doing work on what. The paddler does work on the paddle (pushing it rearward). The paddle does work on the water (pushing it rearward). And, in turn, the paddler's body does work on the boat, pushing it forward. How much work gets done on the boat, from all the thrashing of the paddle, is the key. I believe the original thesis was whether "wing" paddles were more efficient than traditional Euro paddles (ones with an oval-shaped blade on the end of a shaft). Whether a low pressure area is created behind the paddle as it slices through the water may be moot if other features of paddle passage through water are less efficient. I think, to advance the cause, we need __data__ to sort out what's going on in this system. It is too complex to discuss piecemeal or to solve by gedanken analysis. Albeit, it has been fun to scan what you guys have been writing. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Okay, I've been reading the thread on wing paddles. I've found the discussion very interesting regarding energy expended, work done, efficiency, etc. I guess that's what engineers and physicists deal with, huh? (and boat designers and paddlers.) But I have to admit, I don't think I know exactly what a wing paddle is. Could someone give a definition? Thanks! *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Mon, 9 Jun 2003 16:12:16 -0500, "Gordon Snapp" <grsnapp_at_charter.net> said: > Okay, I've been reading the thread on wing paddles. I've found the > discussion very interesting regarding energy expended, work done, > efficiency, etc. I guess that's what engineers and physicists deal > with, huh? (and boat designers and paddlers.) > > But I have to admit, I don't think I know exactly what a wing paddle > is. Could someone give a definition? Thanks! A wing or propeller paddle is shaped more like an airplane propeller. The top of the blade is curved back and the blade itself is cupped and has a twist in it. The blade is also offset from shaft of the paddle. There are some good movies of olympic paddlers using wing paddles on Fred Mechini's page http://pluto.njcc.com/~fmec You can also get a decent idea of what the paddles look like there. The photos of the Bratcha IV give a decent view of the blade shape and an inkling of how the blade is offset from the shaft - on the wing paddles page of http://www.venturesport.com or http://tinyurl.com/dwcp There's an okay picture of the front side of the blade on the paper that Nick referenced: http://www.isbs98.uni-konstanz.de/fullpaper/FullRossSanders.pdf There are pictures of the back of the blade at http://www.oceanpaddlesports.com/paddles.html I wasn't able to locate a picture of an end on view of a wing paddle. If you still want an end on picture let me know. Kirk -- Kirk Olsen kork4_at_cluemail.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 9 Jun 2003 at 20:42, Kirk Olsen wrote: > On Mon, 9 Jun 2003 16:12:16 -0500, "Gordon Snapp" > <grsnapp_at_charter.net> said: > > But I have to admit, I don't think I know exactly what a wing paddle > > is. Could someone give a definition? Thanks! > > A wing or propeller paddle is shaped more like an airplane propeller. > The top of the blade is curved back and the blade itself is cupped and > has a twist in it. The blade is also offset from shaft of the paddle. Most wing paddles look like the ones in the pictures Kirk referred you to, however, there are a few around that are not twisted. If I understand it correctly, the original designs were not twisted and the twist was added later. IIRC, one is referred to as Swedish and the other Norwegian, but I don't remember which is which. There's also one that looks significantly different than this and is not common in racing - the Schleicher from Nimbus paddles. It's not a thin, hollowed blade, but a thicker blade. The photo at http://www.nimbuspaddles.com/graphite.html doesn't capture the shape - you have to see it; odd looking beast. I've played with one in the shop, but never on the water. It supposedly has better handling for sculling and bracing. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Kirk Olsen" <kork4_at_cluemail.com> wrote: >>A wing or propeller paddle is shaped more like an airplane propeller. The top of the blade is curved back and the blade itself is cupped and has a twist in it. The blade is also offset from shaft of the paddle. There are some good movies of olympic paddlers using wing paddles on Fred Mechini's page http://pluto.njcc.com/~fmec You can also get a decent idea of what the paddles look like there. >> Thanks for posting this URL, Kirk. I have handled wing paddles in shops, and done some air-stroking with them, but seeing a world-class paddler use one is a revelation. Well, actually a couple of revelations: 1. Until I get my muscle mass and leanness to where they are, I bet my stroking with a wing would be pretty pitiful. 2. It seems plain to me they are using a lot more intentional paddle-slide to the outside in the last half of the stroke than I do -- I assume this exploits the airfoil character of the paddle shape. And, with that image firmly in my brain, I can believe Nick's data (repeated below my sig; thanks, Nick!) on the greater efficiency of the wing over a conventional Euro paddle. Now I want to see some movies of world-class users of Greenland sticks! Anybody got some? Or, a URL? -- Dave Kruger Astoria, OR -- >From Nick Schade: >> There is some good data about the relative efficiency. The wing paddle is apparently about 89% efficient and the "conventional" paddle blade is about 74% efficient. What is still an open question is why the wind paddle is more efficient. http://www.isbs98.uni-konstanz.de/fullpaper/FullRossSanders.pdf What this means is that even with an efficient wing blade, 11% of all the energy applied to the paddle goes to do things other than pushing the boat forward. >> *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> > Now I want to see some movies of world-class users of Greenland sticks! > Anybody got some? Or, a URL? this is good Dave- http://www.qajaqusa.org/Movies/movies.html > -- http://studiofurniture.com § http://journalphoto.org http://kayakoutfitting.org § http://furnituresociety.org gabriel romeu *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 9 Jun 2003 at 20:43, Dave Kruger wrote: > Now I want to see some movies of world-class users of Greenland > sticks! Anybody got some? Or, a URL? http://www.qajaqusa.org/Movies/movies.html The QajaqUSA web site should be your first source for Greenland info. What's not on the site is probably on their links page. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Glad to see the Inuit technique response. So what is a wing paddle. Simply a design the Polar folk discarded 2000+ - years ago. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Monday, June 9, 2003, at 12:09 PM, Dave Kruger wrote: > Nick Schade <nick_at_guillemot-kayaks.com> wrote: > >>> Work is defined as a change in energy. If you measure the work done >>> by > your hand and you have all the parameters of your paddle matched such > that they multiply together right it is absolutely possible to make the > work done by your hand match with substantially different paddles. But > remember that the work done by your hand is not the same thing as the > work done on your boat. >> > > Nick, a small correction: Classically, work is defined as the force > applied > multiplied by the distance through which the force is applied ( W = f > x d), > not a change in energy. The change in energy in the paddler arm/back > system > is not all directed at accomplishing work. Some goes into generating > turbulence in the water ("vortices") which ultimately ends up heating > up the > water a bit. (The water at the bottom of Niagara Falls is warmer by a > tiny > fraction of a degree because of the "stirring" achieved by the fall and > subsequent random mixing of the water.) W=F x D is just one form for determining the work. In the most generalized form this can be expressed as Work = [delta] Energy. I've double checked this in my physics book. All the change of energy of the paddler arm/back system does perform work, it is just that some of it doesn't do anything we really find useful. Work is done even when all you produce is heat. > > Consequently, if one is interested in determining efficiency in the > paddler/boat/water system, he/she has to be careful to delineate what > is > doing work on what. The paddler does work on the paddle (pushing it > rearward). The paddle does work on the water (pushing it rearward). > And, in > turn, the paddler's body does work on the boat, pushing it forward. > How much > work gets done on the boat, from all the thrashing of the paddle, is > the key. I agree. Often the problem when trying to analyze paddling efficiency people is choosing an appropriate frame of reference. > > I believe the original thesis was whether "wing" paddles were more > efficient > than traditional Euro paddles (ones with an oval-shaped blade on the > end of > a shaft). Whether a low pressure area is created behind the paddle as > it > slices through the water may be moot if other features of paddle > passage > through water are less efficient. The original thesis as I understood it included the idea that a paddle could be 100% efficient. My goal has been to disabuse that notion. > > I think, to advance the cause, we need __data__ to sort out what's > going on > in this system. It is too complex to discuss piecemeal or to solve by > gedanken analysis. Albeit, it has been fun to scan what you guys have > been > writing. There is some good data about the relative efficiency. The wing paddle is apparently about 89% efficient and the "conventional" paddle blade is about 74% efficient. What is still an open question is why the wind paddle is more efficient. http://www.isbs98.uni-konstanz.de/fullpaper/FullRossSanders.pdf What this means is that even with an efficient wing blade, 11% of all the energy applied to the paddle goes to do things other than pushing the boat forward. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Sorry Rich, but just because we were skeptical doesn't mean we think you were lying. Sorry you got that impression, but really that's not what I for one was thinking - and as it turns out, we *were* right - it's not a Sea Lion, but a new boat modified from a Sea Lion - and since you asked about reviews of the boat originally, this is relevant because with a hull modified this much, I wouldn't think any reviews of the stock boat would have much relevance. Richard wrote: > I just have one last question reguarding all you Sea Lion Skeptics. . > . If I were going to make up something to tell the Paddlewise > community, why in the hell would I not have come up with something > much more interesting to lie about? I promise you, if I ever try to > "yank your chain" it will be about my circumnavigation of Greenland, > or my solo crossing of the Pacific. . . not about the existance of > an old $150.00 boat, that isn't even mine. > > Thx Rich. > > P.S. Just so you know , the mystery is solved. I haven't inspected > it myself, but my friend tells me that there are two seems across the > width of the boat just fore and aft of the seat indicating a home made > stretch job. So yes, the 19ft Sea Lion does exist, and no it wasn't > factory. > > *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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