> Jim Martin wrote: > > > > I just want to add that it feels better into the wind. Down here in the > > deep south it's much cooler into the wind. When paddling down wind it > > feels like there is little or no wind. > > Dang, you paddle down wind? Where I paddle the wind is always in my > face, even when I turn around to go back. What's your secret? It seems that the law around here is that you paddle upwind to start out, thinking that the wind will be with you on your way out. It usually works out that the wind dies right about the time I am ready to paddle out so I have to work hard both ways. degamo_at_mindspring.nospam.com *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Kirk wrote; >This past weekend I did a sea kayak race in the Essex >river basin (massachusetts coast, one of my favorite spots >for a day trip). On the trip out to the turn around island >I stayed dead even with someone, going with the current. When >we turned around and headed back up I immediately pulled ahead. > >This is something I've experienced before. I had assumed the speed of a >canoe/kayak was constant relative to the current. > >Could someone explain what would make one hull faster, than the other >with the current versus against it. I would suspect that both of you were actually working harder against the current in whihc case your speed through the water was greater and the boat with the higher prismatic coefficient had lower wave making resistance at the higher speed. >This time the wind direction and waves could have been a factor, last time it >was in windless calm conditions. This could also have been a factor. > >I'm assuming both of us continued putting in the same level >of effort before and after the turn around. Always a dangerous assumption :-) The psychology of the race has a huge impact. Some people feel defeated when paddling against the current and others feel challenged. > >The first time I experienced this was against a marathon flatwater canoe. >I attributed the difference to their boat slicing through the water as >the water was displaced and ours riding up onto the water as it displaced >the water. This time it was a Seda Glider versus a VCP Nordkapp. This is not likley a factor since canoes and kayaks don't plane in the hydrodynamic meaning of the word. Marathon canoes almost always have high prismatic coefficients and are at their best at high speed length ratios. The Glider should be faster than the Nordkapp in racing conditions and at racing effort. Of course, to talke advantage of the length etc. one has to be paddling at Speed/Length >1.0 . Below that they are less efficient because of the added wetted surface. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
On Thu, 28 May 1998, John Winters wrote: > >Could someone explain what would make one hull faster, than the other > >with the current versus against it. > > I would suspect that both of you were actually working harder against the > current in whihc case your speed through the water was greater and the boat > with the higher prismatic coefficient had lower wave making resistance at > the higher speed. During a short race (an hour or less) I like to think my power output is steady/constant. I know it isn't, just humor me. I'm not sure where the higher speed was. Are you saying that upstream we were going at a higher speed than downstream? In both cases the first half of the race, downstream, we were dead even with other boat, within 50 yards of encountering a change in the direction of the current one of the boats pulled away. The first time it happened we were competing against other people of similar experience and fitness/training. One problem with the recent example was the Seda Glider (versus the nordkapp hm) fell back, and I believe the glider has the higher prismatic coefficient. > Always a dangerous assumption :-) The psychology of the race has a huge > impact. Some people feel defeated when paddling against the current and > others feel challenged. ;-) Psychology was likely a factor in the most recent case. The person in the glider fell back about 15 seconds after I commented that we would have a headwind and quartering waves for the second half of the race too. > >The first time I experienced this was against a marathon flatwater canoe. > >I attributed the difference to their boat slicing through the water as > >the water was displaced and ours riding up onto the water as it displaced > >the water. This time it was a Seda Glider versus a VCP Nordkapp. > > This is not likley a factor since canoes and kayaks don't plane in the > hydrodynamic meaning of the word. I didn't mean planing. I meant that the recreational canoe hull was more likely to ride up onto the water and have more of a downward force as the water was displaced, versus the marathon boat forcing the water more outward than down. > The Glider should be faster than the Nordkapp in racing conditions and at > racing effort. So a simple psych-out is the answer? ;-) Maybe in the more recent case. kirk *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
-----Original Message----- From: Kirk Olsen <kolsen_at_imagelan.com> To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net> Date: Tuesday, May 26, 1998 1:49 PM Subject: [Paddlewise] speed with versus against the current > >This past weekend I did a sea kayak race in the Essex >river basin (massachusetts coast, one of my favorite spots >for a day trip). On the trip out to the turn around island >I stayed dead even with someone, going with the current. When >we turned around and headed back up I immediately pulled ahead. > >This is something I've experienced before. I had assumed the speed of a >canoe/kayak was constant relative to the current. > >Could someone explain what would make one hull faster, than the other >with the current versus against it. > >This time the wind direction and waves could have been a factor, last time it >was in windless calm conditions. > >I'm assuming both of us continued putting in the same level >of effort before and after the turn around. > >The first time I experienced this was against a marathon flatwater canoe. >I attributed the difference to their boat slicing through the water as >the water was displaced and ours riding up onto the water as it displaced >the water. This time it was a Seda Glider versus a VCP Nordkapp. > > >On a separate note Sunday afternoon I got to enjoy my first unplanned swim >from the surf ski. Pulling up on a knee, to brace in waves, only works in >boats with a deck... > >kirk It has always seemed to me harder to paddle against the current as opposed to with. I mean that even with my eyes closed I think I can feel the difference, i.e., without looking at the fixed shoreline. I always attributed this to my imagination since I can't think of a physical reason it could be true. Jerry *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Along these same lines, I'm new to kayaking and I've been going out recently on a lake. For some reason, I seem to paddle straighter and easier going INTO the wind and against the current, heading into the waves. When I turn around and head to shore the way I came but with the wind at my back, I feel awkward and have a hard time keeping on a straight course. Is this difference because it's a lake rather than a river? Thanks, Donna Gerald Foodman wrote: > It has always seemed to me harder to paddle against the current as opposed > to with. I mean that even with my eyes closed I think I can feel the > difference, i.e., without looking at the fixed shoreline. I always > attributed this to my imagination since I can't think of a physical reason > it could be true. > > Jerry > -- ************************ D.R. Ferron Photography D.R. Ferron, Photographer and Writer drferron_at_bellatlantic.net *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
D.R. Ferron wrote: > Along these same lines, I'm new to kayaking and I've been going out recently on > a lake. For some reason, I seem to paddle straighter and easier going INTO the > wind and against the current, heading into the waves. When I turn around and > head to shore the way I came but with the wind at my back, I feel awkward and > have a hard time keeping on a straight course. Is this difference because it's > a lake rather than a river? > > Thanks, Donna > > > > -- > > *************************************************************************** It might be the waves and not the wind that is causing your problem. When hit from behind by a wave boats try to broach, or turn sideways to the wave. All boats tend to broach at least a little, some more than others. The design of the stern is the deciding factor here. Or, if your trim is a little bow heavy, the wind would act as an aid in tracking upwind, but work against you downwind. Try putting a gallon container full of water in the stern and see if it helps. Mike -- Paddling along through fog so thick that only one's thoughts are visible, your reverie is abruptly shattered by the ancient cry of a great blue heron as she lifts uncertainly from the brilliant blue of a mussel-shell beach witnessed only by the brooding, wet spruce....your passage home seems as much back through time as it does through space. Mark H Hunt *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Jerry wrote; > >It has always seemed to me harder to paddle against the current as opposed >to with. I mean that even with my eyes closed I think I can feel the >difference, i.e., without looking at the fixed shoreline. I always >attributed this to my imagination since I can't think of a physical reason >it could be true. > I believe this has to do with one's normal stroke rate. If you are paddling at your normal still water stroke up current the force on your paddle will be less because the paddle speed through the water is lower. To get the same velocity to the water you have to increase the paddle velocity relative to you. Even though the paddle force is the same your rate is higher and that may give the sensation of greater work. Bruce Winterbon once called to my attention to an interesting phenomenon involving the force developed when the blade is inserted in the crest of a wave as opposed to the trough. The ideal would seem to be to make sure the paddle was always inserted in the wave where the flow was opposite the action of the paddle blade for greatest thrust. This may even have some nit picking effect on rolling since the lift effect would be greater when blade is travelling against the flow. Donna wrote; >Along these same lines, I'm new to kayaking and I've been going out recently on >a lake. For some reason, I seem to paddle straighter and easier going INTO the >wind and against the current, heading into the waves. When I turn around and >head to shore the way I came but with the wind at my back, I feel awkward and >have a hard time keeping on a straight course. Is this difference because it's >a lake rather than a river? The reasons for this are rather complicated. Maybe this much simplified explanation will help. The water molecules in a wave travel in circular orbits. At the crest they travel with the wave but in the trough they travel in the opposite direction. When paddling down wind the bow might be in the trough while the stern will be on the crest (also vice versa) . If there is any angle (almost always) there is a turning moment on the boat causing it to veer off course. This is aggravated as the boat travels more closely to the wave speed (period of encounter) when the forces have more time to act on the boat. Against the wind the period of encounter is very short and the relative flow is always in the same direction so there are no (or minimal) turning moments. The only time being in a lake or river would make a difference is when the waves are due to the river flow rather than wind driven waves. Waves cause by velocity variations in a river behave differently from waves caused by wind. If that isn't clear let me know and I will try again. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
On Fri, 29 May 1998, John Winters wrote: > Jerry wrote; > > > > >It has always seemed to me harder to paddle against the current as opposed > >to with. I mean that even with my eyes closed I think I can feel the > >difference, i.e., without looking at the fixed shoreline. I always > >attributed this to my imagination since I can't think of a physical reason > >it could be true. > > > > > I believe this has to do with one's normal stroke rate. If you are paddling > at your normal still water stroke up current the force on your paddle will > be less because the paddle speed through the water is lower. To get the > same velocity to the water you have to increase the paddle velocity > relative to you. Even though the paddle force is the same your rate is > higher and that may give the sensation of greater work. I'm not sure about this. When you say "the sensation of greater work" do you mean that you feel like you're working harder, or that you feel like you're working more efficiently (i.e. more results for same level of effort)? I definitely find that it feels easier to paddle into a light-moderate headwind and seas than to paddle with a light-moderate tailwind and following seas - same as what Jerry was saying. You said that when going upstream: > the force on your paddle will > be less because the paddle speed through the water is lower Now I never took physics past high school, and I'm not mechanical, but won't the force on your paddle be the combination of your force against the water and the water's force against your paddle? So the paddle speed is lower because there is opposing force from the water, but in fact the combined forces should be the same, no? I've never timed myself going upstream and downstream over the same distance in the same conditions. However, I think one of my paddling buddies said he did, and it wasn't an illusion of speed - he actually went upstream/upwind faster than downstream downwind. (Greg, have I got that right?) Earlier this week, before reading this stream, I found just the same thing - out on a lake in a borrowed K-light, going downwind with small following swells was no fun and the boat didn't handle well and definitely moved slowly. I thought I was just tired, but when I turned to go home I positively flew, and it was a blast! I really wish I had timed it. Joy Hecht Arlington VA > > Bruce Winterbon once called to my attention to an interesting phenomenon > involving the force developed when the blade is inserted in the crest of a > wave as opposed to the trough. The ideal would seem to be to make sure the > paddle was always inserted in the wave where the flow was opposite the > action of the paddle blade for greatest thrust. This may even have some nit > picking effect on rolling since the lift effect would be greater when blade > is travelling against the flow. > > Donna wrote; > > >Along these same lines, I'm new to kayaking and I've been going out > recently on > >a lake. For some reason, I seem to paddle straighter and easier going > INTO the > >wind and against the current, heading into the waves. When I turn around > and > >head to shore the way I came but with the wind at my back, I feel awkward > and > >have a hard time keeping on a straight course. Is this difference because > it's > >a lake rather than a river? > > The reasons for this are rather complicated. Maybe this much simplified > explanation will help. > > The water molecules in a wave travel in circular orbits. At the crest they > travel with the wave but in the trough they travel in the opposite > direction. When paddling down wind the bow might be in the trough while the > stern will be on the crest (also vice versa) . If there is any angle > (almost always) there is a turning moment on the boat causing it to veer > off course. This is aggravated as the boat travels more closely to the wave > speed (period of encounter) when the forces have more time to act on the > boat. Against the wind the period of encounter is very short and the > relative flow is always in the same direction so there are no (or minimal) > turning moments. > > The only time being in a lake or river would make a difference is when the > waves are due to the river flow rather than wind driven waves. Waves cause > by velocity variations in a river behave differently from waves caused by > wind. > > If that isn't clear let me know and I will try again. > > Cheers, > John Winters > Redwing Designs > Specialists in Human Powered Watercraft > http://home.ican.net/~735769/ > > (Greg, Mike - in case you're not on Paddlewise, I thought this discussion would interest you. I think you have to be on the list to respond, though. - Joy) *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
John Winters wrote: (Donna wrote:) > >When I turn around and > >head to shore the way I came but with the wind at my back, I feel awkward and > >have a hard time keeping on a straight course. Is this difference because it's > >a lake rather than a river? > > The reasons for this are rather complicated. Maybe this much simplified > explanation will help. > > The water molecules in a wave travel in circular orbits. At the crest they > travel with the wave but in the trough they travel in the opposite > direction. When paddling down wind the bow might be in the trough while the > stern will be on the crest (also vice versa) . If there is any angle > (almost always) there is a turning moment on the boat causing it to veer > off course. This is aggravated as the boat travels more closely to the wave > speed (period of encounter) when the forces have more time to act on the > boat. Against the wind the period of encounter is very short and the > relative flow is always in the same direction so there are no (or minimal) > turning moments. > > The only time being in a lake or river would make a difference is when the > waves are due to the river flow rather than wind driven waves. Waves cause > by velocity variations in a river behave differently from waves caused by > wind. The above (response to Donna) is correct, as well as qute lucid -- thanks, John. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Winters wrote: > > Jerry wrote: > > > > > >It has always seemed to me harder to paddle against the current as opposed > > >to with. I mean that even with my eyes closed I think I can feel the > > >difference, i.e., without looking at the fixed shoreline. I always > > >attributed this to my imagination since I can't think of a physical reason > > >it could be true. > > I believe this has to do with one's normal stroke rate. If you are paddling > at your normal still water stroke up current the force on your paddle will > be less because the paddle speed through the water is lower. To get the > same velocity [through] the water you have to increase the paddle velocity > relative to you. Even though the paddle force is the same your rate is > higher and that may give the sensation of greater work. I have about the same experience as Winters, and agree with John's analysis here. There is another effect, however. It is most apparent at the transition time when one crosses from water going WITH you to water going AGAINST you. In fact, most times when I paddle across a shear line onto a "new" batch of water which is moving AGAINST my motion, it momentarily "feels" easier. Here's my tentative analysis: Imagine yourself paddling in water which is traveling in the same direction you are, and at a comfortable cadence and paddle force, at a CONSTANT velocity. In the language of physics, the forces of resistance on the paddler/boat system are exactly balanced by the propulsive forces on the system, so the NET force on the system is zero. (To slow down or speed up, the NET force has to change.) The resistive forces are: 1. water resistance (FW), and, 2. air resistance (FA). The propulsive force (FP) is that from the paddle interacting with the water. So, the relationship is: FP = FW + FA As you slide across the shear line onto water which is going AGAINST your motion, the momentum of the paddler/boat system will maintain your velocity for a second or so. BUT, because the water is now sliding past your boat at a greater relative velocity, you will find that (momentarily) paddling gets "easier" at the *same* cadence you had before. In other words, (momentarily) the paddle force drops -- that's why it feels "easier." (This is like the effect which occurs as one briskly walks on fixed ground and steps onto a treadmill moving AGAINST your direction -- it feels like your feet will fly out from underneath you! Try it!) Of course, soon you notice you have slowed down relative to a fixed point on the shore, and you increase your cadence (and paddle force) to regain the same effort you were putting out before. BUT, because of the opposing current, your true speed *over ground* will be SMALLER. This makes the resistance due to the air, FA, SMALLER because you are travelling less rapidly through the air. Now go look at the little equation I wrote above. If FA is smaller than it was before, and you are truly putting out the same "effort" -- meaning FP is about the same magnitude as before -- then the resistance due to passage through the water (FW) must be GREATER. This can occur only if your hull speed through the water is greater, so your craft will be moving *through the water* a little faster. No, you won't be travelling over the ground faster than before, because the opposing current offsets some of that hull speed. BUT, you may experience the sensation of "easier" travel, if you focus on the water and notice you are travelling through it faster than before. That's what I experience when paddling against a current -- exactly the opposite sensation which Jerry experiences. In fact, when paddling *with* the current, I notice I have to apply a markedly GREATER force on the paddle (at the same cadence), and feel I am working harder going *with* the current -- which makes sense, because there is greater air resistance at the greater speed over the ground. Sometime I should paddle with Jerry and we should discuss these "sensations" and try to sort out the differences in our perceptions. Sorry for going on so long. Took a lot of words to get this out. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Joy wrote; (SNIP) > >I'm not sure about this. When you say "the sensation of greater work" do >you mean that you feel like you're working harder, or that you feel like >you're working more efficiently (i.e. more results for same level of >effort)? I definitely find that it feels easier to paddle into a >light-moderate headwind and seas than to paddle with a light-moderate >tailwind and following seas - same as what Jerry was saying. Whenever one changes pace from natural pace to a new slower or faster pace the sensation of work increases even if effective work remains constant. > >You said that when going upstream: > >> the force on your paddle will >> be less because the paddle speed through the water is lower > >Now I never took physics past high school, and I'm not mechanical, but >won't the force on your paddle be the combination of your force against >the water and the water's force against your paddle? So the paddle speed >is lower because there is opposing force from the water, but in fact the >combined forces should be the same, no? The force on the paddle is F = CdAv^2 If velocity through the water is reduced the force is reduced. When you are paddling upstream the water has a velocity in the same direction as your paddle. In context, to maintain the same thrust while paddling upstream one must paddle at a faster blade velocity relative to the paddler (and boat). To develop the same thrust as you would in still water the blade velocity through the water must be the same. > >I've never timed myself going upstream and downstream over the same >distance in the same conditions. However, I think one of my paddling >buddies said he did, and it wasn't an illusion of speed - he actually went >upstream/upwind faster than downstream downwind. (Greg, have I got that >right?) Not very likely. > >Earlier this week, before reading this stream, I found just the same >thing - out on a lake in a borrowed K-light, going downwind with small >following swells was no fun and the boat didn't handle well and >definitely moved slowly. I thought I was just tired, but when I turned >to go home I positively flew, and it was a blast! I really wish I had >timed it. Here you are adding an additional factor - a boat that handles poorly. If it were a better handling boat your downwind speed would have been much better than your upwind speed. You might even get the boat to surf if the waves were large enough. It is possible that some boats handle so poorly downwind that they might actually be slower but that is never the case with a well designed boat. Anyone with such a poor boat should seriously consider selling it to some poor unsuspecting chump that you don't much like. Do not confuse the performance of one boat with the performance of all boats. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
I may have a fundamental misunderstanding of the original post, but I will comment anyway: John Winters wrote (in response to Joy): > >snip > > > >Now I never took physics past high school, and I'm not mechanical, but > >won't the force on your paddle be the combination of your force against > >the water and the water's force against your paddle? So the paddle speed > >is lower because there is opposing force from the water, but in fact the > >combined forces should be the same, no? > > The force on the paddle is F = CdAv^2 > > If velocity through the water is reduced the force is reduced. When you are > paddling upstream the water has a velocity in the same direction as your > paddle. In context, to maintain the same thrust while paddling upstream > one must paddle at a faster blade velocity relative to the paddler (and > boat). To develop the same thrust as you would in still water the blade > velocity through the water must be the same. The V, of course, is velocity of the paddle relative to the water. So, if you are paddling with the same cadence and stroke length, etc. (neglecting for the moment the effect of wind speed on your velocity relative to the water), you produce the same thrust whether you are paddling upstream or down. You also move at the same velocity relative to the water. Your speed made good (speed over ground) is then the vector sum of your velocity relative to the water and the velocity of the water relative to the ground. Of course, you do feel your acceleration/deceleration (relative to ground) when you enter water that is moving. Maybe that's the basis for the feeling that you're working harder when you're paddling in a contrary current. It doesn't explain the apparent difference in boat performance, however... > > > > >I've never timed myself going upstream and downstream over the same > >distance in the same conditions. However, I think one of my paddling > >buddies said he did, and it wasn't an illusion of speed - he actually went > >upstream/upwind faster than downstream downwind. (Greg, have I got that > >right?) > > Not very likely. > > > > >Earlier this week, before reading this stream, I found just the same > >thing - out on a lake in a borrowed K-light, going downwind with small > >following swells was no fun and the boat didn't handle well and > >definitely moved slowly. I thought I was just tired, but when I turned > >to go home I positively flew, and it was a blast! I really wish I had > >timed it. > > Here you are adding an additional factor - a boat that handles poorly. If > it were a better handling boat your downwind speed would have been much > better than your upwind speed. You might even get the boat to surf if the > waves were large enough. It is possible that some boats handle so poorly > downwind that they might actually be slower but that is never the case with > a well designed boat. Anyone with such a poor boat should seriously > consider selling it to some poor unsuspecting chump that you don't much > like. > > Do not confuse the performance of one boat with the performance of all > boats. I have noticed that when paddling with the wind, I "feel" like I'm going slower. But I'm pretty sure it's just because my velocity relative to the wind and waves is slower, so it "appears" like I'm going slower. In hot weather, I think the additional cooling one gets when paddling into the wind is significant. Also, sometimes when going with the waves (wind), I have to work harder to keep the boat going straight. Especially if I'm using poor technique. This is related to wind and waves, and not directly to current speed/direction. My contribution, Dave Carlson *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
At 10:04 PM 5/29/98 -0700, > >> > Jerry wrote: >> > > >> > >It has always seemed to me harder to paddle against the current as opposed >> > >to with. I mean that even with my eyes closed I think I can feel the >> > >difference, i.e., without looking at the fixed shoreline. I always >> > >attributed this to my imagination since I can't think of a physical reason >> > >it could be true. >> OK. . . here's a "literary critical" take on this question. Let's "problematize" the reading of "harder." In addition to "harder" meaning "more strenuous" it can also imply "requiring more skill and attention." This latter reading was in fact my first take on this statement. I think it's a given that paddling in following seas is some of the most demanding because the waves sneak up behind you, and because of many boat's tendency to broach in following seas. The rest of the paragraph *suggests* "more strenuous" as implied particularly in the allusion to sensations of relative speed contained in the clause: "without looking at the fixed shoreline." Nonetheless, I'd suggest that paddling may seem "harder" in the broadest of connotations, not only because the paddling may seem more involved (i.e. "harder") but also because the flow of the water is not coming past the boat and instead is flowing with the boat thereby providing the sensation of less speed. So is this a question of hydro-physics or a demonstration of "textual indeterminacy" and problematic reading? Geo. M.A. Lit., M.A. Linguistics Rhetorician/Provacateur In a SW suburb of Portland *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Dave wrote; (Large SNIP) > >As you slide across the shear line onto water which is going AGAINST >your motion, the momentum of the paddler/boat system will maintain your >velocity for a second or so. BUT, because the water is now sliding past >your boat at a greater relative velocity, you will find that >(momentarily) paddling gets "easier" at the *same* cadence you had >before. In other words, (momentarily) the paddle force drops -- that's >why it feels "easier." (This is like the effect which occurs as one >briskly walks on fixed ground and steps onto a treadmill moving AGAINST >your direction -- it feels like your feet will fly out from underneath >you! Try it!) I wish I had said that. The analogy is apt. Just last week I was at the Milwaukee airport and almost fell on my butt for this reason. Can't talk and walk at the same time :-) Wish I had your way with words Dave. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
George M.A. Lit., M.A. Linguistics Rhetorician/Provacateur wrote; > OK. . . here's a "literary critical" take on this question. Let's >"problematize" the reading of "harder." In addition to "harder" meaning >"more strenuous" it can also imply "requiring more skill and attention." >This latter reading was in fact my first take on this statement. I think >it's a given that paddling in following seas is some of the most demanding >because the waves sneak up behind you, and because of many boat's tendency >to broach in following seas. Good point and this ties in with the "perceived effort" that we have been talking about. It works both ways. Those who enjoy downwind paddling find it easy even when they are busting their butt to catch a wave. > (SNIP) > So is this a question of hydro-physics or a demonstration of >"textual indeterminacy" and problematic reading? Always a possibility. That's what makes it so interesting. Does the couple experiencing simultaneous orgasm have the same view as the researcher studying the event? Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
David wrote; (SNIP) > >The V, of course, is velocity of the paddle relative to the water. So, >if you are paddling with >the same cadence and stroke length, etc. (neglecting for the moment the >effect of >wind speed on your velocity relative to the water), you produce the same >thrust whether you >are paddling upstream or down. Keep in mind that you are paddling at the same cadence relative to the boat and yourself. The paddle velocity relative to the water is the key point. The thrust developed is a function not of the paddle velocity relative to the boat but the velocity relative to the water. >You also move at the same velocity >relative to the water. Maybe maybe not. Even if the force developed is the same you may not move at the same speed due to the way the transverse wave system forms around the boat. I don't klnow if nayone has studied this but my observation is that the wave system created by the boat is much modified by the flowing water. Perhaps Bruce has some thoughts on this. Are you there Bruce? >Your speed made good (speed over ground) is then the vector sum of your >velocity >relative to the water and the velocity of the water relative to the >ground. Also not necessarily so since it assumes that the two are perfectly additive but they aren't because of the time between strokes when the boat will slow at different rates. > >Of course, you do feel your acceleration/deceleration (relative to >ground) when >you enter water that is moving. Maybe that's the basis for the feeling >that >you're working harder when you're paddling in a contrary current. It >doesn't >explain the apparent difference in boat performance, however... A good possibility. We feel the tug on the boat and maybe that gives a sensation of speed. (SNIP) >I have noticed that when paddling with the wind, I "feel" like I'm going >slower. But >I'm pretty sure it's just because my velocity relative to the wind and >waves is >slower, so it "appears" like I'm going slower. In hot weather, I think >the additional >cooling one gets when paddling into the wind is significant. Also, >sometimes when going >with the waves (wind), I have to work harder to keep the boat going >straight. Especially >if I'm using poor technique. This is related to wind and waves, and not >directly >to current speed/direction. That is A really important point that Dan makes. Often our sensations of speed are not consistent with speed and that is why designers either like or dislike subjective opinions of speed depending on the result. :-) Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ . and *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
-----Original Message----- From: John Winters <735769_at_ican.net> To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net> Date: Saturday, May 30, 1998 4:18 PM Subject: Re: [Paddlewise] speed with versus against the current >David wrote; > >(SNIP) >> >>The V, of course, is velocity of the paddle relative to the water. So, >>if you are paddling with >>the same cadence and stroke length, etc. (neglecting for the moment the >>effect of >>wind speed on your velocity relative to the water), you produce the same >>thrust whether you >>are paddling upstream or down. > >Keep in mind that you are paddling at the same cadence relative to the boat >and yourself. The paddle velocity relative to the water is the key point. >The thrust developed is a function not of the paddle velocity relative to >the boat but the velocity relative to the water. > >>You also move at the same velocity >>relative to the water. > >Maybe maybe not. Even if the force developed is the same you may not move >at the same speed due to the way the transverse wave system forms around >the boat. I don't klnow if nayone has studied this but my observation is >that the wave system created by the boat is much modified by the flowing >water. Perhaps Bruce has some thoughts on this. Are you there Bruce? > >>Your speed made good (speed over ground) is then the vector sum of your >>velocity >>relative to the water and the velocity of the water relative to the >>ground. > >Also not necessarily so since it assumes that the two are perfectly >additive but they aren't because of the time between strokes when the boat >will slow at different rates. >> In my note in this thread I was referring only to paddling with or against current. No wind; No waves. I think, (not sure), that with my eyes closed I could tell whether it was with or against. John Winters says that the velocities of water, and of boat with respect to water, are "not necessarily additive". This accords with my sense. But I still can't think why, assuming that you are in a steady state and not crossing eddylines. As far as wind is concerned (another topic entirely), I can't imagine why a wind at your back is not easier from an effort, not handling, point of view than a wind in your face. Jerry *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Kirk wrote; > >During a short race (an hour or less) I like to think my power output is >steady/constant. I know it isn't, just humor me. I'm not sure where >the higher speed was. Are you saying that upstream we were going at >a higher speed than downstream? In both cases the first half of the >race, downstream, we were dead even with other boat, within 50 yards >of encountering a change in the direction of the current one of the >boats pulled away. The first time it happened we were competing >against other people of similar experience and fitness/training. Could have been going faster through the water. People react to adversity differently. (SNIP) > >> >The first time I experienced this was against a marathon flatwater canoe. >> >I attributed the difference to their boat slicing through the water as >> >the water was displaced and ours riding up onto the water as it displaced >> >the water. This time it was a Seda Glider versus a VCP Nordkapp. >> >> This is not likely a factor since canoes and kayaks don't plane in the >> hydrodynamic meaning of the word. > >I didn't mean planing. I meant that the recreational canoe hull was more >likely to ride up onto the water and have more of a downward force as the >water was displaced, versus the marathon boat forcing the water more outward >than down. Not sure what you mean here. In displacement mode the pressure on the hull always acts normal to the hull surface but that doesn't mean it has more "lift" since the total hydrostatic forfec is equal to the displacement regardless of hull shape. . > >> The Glider should be faster than the Nordkapp in racing conditions and at >> racing effort. > >So a simple psych-out is the answer? ;-) >Maybe in the more recent case. I would be proud of myself. If I can get hold of the Glider's lines I will run a resistance check and let you know what the difference might be. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
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