"The other comment here is, "A skeg is a failed rudder."" I can't agree with this. A skeg is a device for adjusting the center of lateral resistance of a boat whereas a rudder is a device for causing the boat to turn relative to the water. They serve differrent purposes. Nick Lyle *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
At 12:25 pm 14/10/99 -0700, you wrote: >"The other comment here is, "A skeg is a failed rudder."" > >I can't agree with this. A skeg is a device for adjusting the center of >lateral resistance of a boat whereas a rudder is a device for causing >the boat to turn relative to the water. They serve differrent purposes. > >Nick Lyle They set out to achieve the same result in slightly different ways, that is, change the handling of the kayak. The rudder straight ahead obviously changes the centre of lateral resistance (like a skeg set further aft) AND also can be used to cause the kayak to turn. Two jobs - one device? Alex . . Alex (Sandy) Ferguson Chemistry Department University of Canterbury New Zealand *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Nick Wrote: > >I can't agree with this. A skeg is a device for adjusting the center of > >lateral resistance of a boat whereas a rudder is a device for causing > >the boat to turn relative to the water. They serve differrent purposes. Then Alex said: > They set out to achieve the same result in slightly different ways, that > is, change the handling of the kayak. The rudder straight ahead obviously > changes the centre of lateral resistance (like a skeg set further aft) AND > also can be used to cause the kayak to turn. > > Two jobs - one device? I'm not arguing, just trying to match what is being discussed with my (limited) experience with skegs and rudders: I agree the rudder changes the lateral resistance, but it's more like a switch, on or off. (In the water or out) Both a rudder and skeg are designed to help you hold a given course. I've been taught that a rudder is not for turning and the kayak should still be leaned to help turn even with a rudder. A rudder helps hold course by applying a turning force that holds you in the direction you want to go. (I know, crappy description. Someone can explain this better than me) A skeg helps hold course by controlling at what angle (to the wind) the bow and stern reach equilibrium and slip sideways at equal speeds. Retracted, a skegged boat should turn into the wind (the stern initially slips faster than the bow until it is pointed into the wind). As the skeg is deployed, the stern slips less, and the bow turns into the wind less before it reaches equilibrium. Continuing to deploy the skeg further will find the bow and stern at right angles to the wind (the bow and stern now have equal lateral resistance). Fully deploying the skeg should have the stern more laterally resistant and the bow is now downwind of the stern. So, a rudder helps you hold course by applying a turning force to counteract the turning force of the wind. And a skeg helps you hold course by controlling the amount of lateral drag difference between your bow and stern. Is this description somewhat correct? Woody P.S. Yeah, I still use my rudder to turn my kayak, but I try not to as the turning radius is very large when just using the rudder. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
"They set out to achieve the same result in slightly different ways, that is, change the handling of the kayak. The rudder straight ahead obviously changes the centre of lateral resistance (like a skeg set further aft) AND also can be used to cause the kayak to turn. Two jobs - one device? Alex" I don't mean to be a pedant, but there is a functional differrence between skeg and rudder. The skeg allows adjustment of the center of lateral resistance over a range. This is supposed to allow you to fine tune the ballance of the boat in the wind, perhaps from weather helm, through neutral helm and all the way over to lee helm. In practice you should be able to set the skeg at a certain spot and leave it while you paddle the kayak in perfect ballance on a given course. I haven't got a skeg om my own boat, so I haven't been able to test this very extensively myself. With a rudder you do alter the center of lateral resistance when you drop the rudder, but you cannot adjust the CLR over a range, instead you must continually maintain a certain rudder position to steer the boat onto it's course. Nick Lyle *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
>I don't mean to be a pedant, but there is a functional differrence >between skeg and rudder. OK, but the final result which is what I was "short-circuiting" the discussion to..... >...In practice you >should be able to set the skeg at a certain spot and leave it while you >paddle the kayak in perfect ballance on a given course. In theory... > With a rudder you do alter the center of lateral >resistance when you drop the rudder, but you cannot adjust the CLR over >a range, instead you must continually maintain a certain rudder >position to steer the boat onto it's course. Given wind = waves, so one "kicks" a little rudder on to redirect the heading as required (start a heading change), not necessarily leaving a rudder angle on all the time. Depends on the wind and wave angles and boat's reaction/amount of weather helm as to whether there will be more drag from a constant rudder angle or occassional. The skeg is there all the time. The skeg can need "fiddling" with, using one hand while the rudder uses the otherwise unused feet. AND THERE ARE NO MUSHY pedal conplaints please. Any complains are your (or the kayak builder's) fault. Alex . . Alex (Sandy) Ferguson Chemistry Department University of Canterbury New Zealand *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 10/14/99 11:56:26 PM EST, woodardr_at_tidalwave.net writes: > > A skeg helps hold course by controlling at what angle (to the wind) the bow > and stern reach equilibrium and slip sideways at equal speeds. Retracted, a > skegged boat should turn into the wind (the stern initially slips faster > than the bow until it is pointed into the wind). As the skeg is deployed, > the stern slips less, and the bow turns into the wind less before it > reaches equilibrium. Continuing to deploy the skeg further will find the bow > and stern at right angles to the wind (the bow and stern now have equal > lateral resistance). Fully deploying the skeg should have the stern more > laterally resistant and the bow is now downwind of the stern. > > So, a rudder helps you hold course by applying a turning force to counteract > the turning force of the wind. And a skeg helps you hold course by > controlling the amount of lateral drag difference between your bow and > stern. > > Is this description somewhat correct? It's the most meaningful description I've ever read. Hank Berger *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
The drop down skeg VS rudder discussion provides a pleasant change form the usual rudder VS no rudder debate and gives me the opportunity to serve up some more pedantry. :-) First, drop down skegs and rudders "do" the same thing, I.E. they alter the turning moments about the Center of Gravity. Both can provide lift due to an angle of attack with the water flow. You can get a more complete discussion of these turning moments at http://home.ican.net/~735769/control.htm Often we tend to think of directional stability in terms of the center of lateral area and, while valid for hulls and control surfaces that generate little or no lift it doesn't really apply well to lifting surfaces. Sailboat designers learned that early on when they shifted from long keels to high lift keels and their "rule of thumb" methods for finding the center of lateral resistance no longer worked so well. Rudders increase the effect by allowing an even greater angle of attack and, if the rudder has a suitable section shape, it can provide significant increases in lift. The two differ in degree of effect and in the ability of one to allow a wider range of effect over the other. The skeg varies the turning moments through adjusting the exposed area and the rudder (most often) adjusts it by altering the angle of attack. In anticipation of some one raising the resistance issue, it seems that rudders more resistance per unit area due to surface piercing effects or, in the case of under hull rudders, due to cross over effects between the hull and rudder but that does not mean that the net effort to paddle the boat increases. As I have pointed out before, if the designer plans on using a rudder or skeg he can design the boat with significantly less surface area that, when coupled with any reductions in leeway and reductions in resistance due to heel should offset the added resistance of the rudder. Unfortunately most people look at rudders and skegs as "additive" only as in "If we add a rudder to XYZ boat it will have more resistance" rather than "if we design boat ABC for a rudder or a skeg it will have less". Individually one has to decide whether one sees operating a rudder with the feet over a skeg with the hands as an advantage. One can easily set up the skeg to operate with the feet so I don't see any inherent advantage in one over the other in operation. I personally have no problem with deck mounted controls but that has to do with my style of paddling. I kind of enjoy steering with the paddle and heel but then I come from a canoe background. An interesting aspect of skegs comes from their location. Both skegs and rudders generate lift to offset leeway. A skeg mounted well forward would work in much the same way as a centerboard on a sail boat producing a net increase in efficiency when paddling in conditions that produce leeway. A rather neat aspect deriving (possibly) from a more amidships location comes in the form of both reducing leeway and weathercocking that, depending upon the shape of the hull, may not inhibit maneuverability. Alex makes a good point when he blames builders for mushy foot pegs. I would place the blame for include almost every ill attributed to rudders (Ditto for skegs) squarely on the backs of builders. Floppy, flat plate rudders with improperly swaged fittings and nylon straps for length adjustment etc. will make a person weep. Many of the ills ascribed to rudders have nothing to do with rudders and a lot to do with builders. I have seen swages crimped with pliers, no thimbles, wires bearing on the threads of bolts, stretchy nylon adjustment straps, foot pegs that slide right of the tracks, Etc. Etc. If we had built sailboats that way we would have lots more room at marinas and overcrowding in cemeteries. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
> Rudders increase the effect by allowing an even greater angle of > attack and, > if the rudder has a suitable section shape, it can provide significant > increases in lift. The two differ in degree of effect and in the > ability of > one to allow a wider range of effect over the other. I've seen you guys refer to rudders and lift before. I've seen reference to making rudders in a foil shape, is this what you mean by section shape? I've seen probably 30-40 rudders mounted on kayaks, but they've all been the flat blade types, although I've been told foil shaped blades exist. > An interesting aspect of skegs comes from their location. Both skegs and > rudders generate lift to offset leeway. Here is where I'm really lacking in understanding all of this: How does a skeg, essentially a flat piece of metal or composite, aligned with the boat, generate lift? I see the skeg as creating lateral resistance. Is this the same thing as lift? Woody *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert Woodard wrote: > > > Rudders increase the effect by allowing an even greater angle of > > attack and, > > if the rudder has a suitable section shape, it can provide significant > > increases in lift. > I've seen you guys refer to rudders and lift before. I've seen reference to > making rudders in a foil shape, is this what you mean by section shape? I've > seen probably 30-40 rudders mounted on kayaks, but they've all been the flat > blade types, although I've been told foil shaped blades exist. > > > An interesting aspect of skegs comes from their location. Both skegs and > > rudders generate lift to offset leeway. > > Here is where I'm really lacking in understanding all of this: How does a > skeg, essentially a flat piece of metal or composite, aligned with the boat, > generate lift? I see the skeg as creating lateral resistance. Is this the > same thing as lift? Woody, I'm pretty sure they are talking about "lift" to the side, which can not be generated without some resistance (an aircraft maxim: no drag, no lift; high lift to drag *ratio* is good; low lift to drag ratio is bad). In other words, a force at right angles to the rudder/skeg surface. So, the rudder/skeg, when hit from the left (port) side, for example, by water as you move through it, produces a force, due to its "airfoil" shape and its angle of attack, to the right, analogous to the lift (in the vertical direction) which an airplane wing generates as it moves through air. Any airfoil which moves through any fluid, be it air or water, will generate "lift" if it has a positive angle of attack (ignoring stalling, to simplify things). The discussion about the influence of rudder/skeg cross-sectional shape ("airfoil" used in a different sense) on the *efficiency* of the lift/drag combination seems to be drifting towards the conclusion that flat plates are not as good as virtually any airfoil, and that some airfoils are better than others. Winters (and others) must have tank test and/or field test data to suggest what is the best airfoil. At the Reynolds numbers a yak rudder operates at, I wonder how much difference it might make, and am really curious what data exist to show an airfoil makes enough difference for me to notice when paddling. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Dave K wrote: > Any airfoil which moves through any fluid, be it air or water, > will generate > "lift" if it has a positive angle of attack (ignoring stalling, > to simplify > things). Ok, I understand that part, but how does a skeg get applied at a positive angle? Doesn't it run in line with the keel (and direction of travel)? I can understand the rudder producing lift, as it can be turned to a positive direction (left or right). But, a skeg I just can't seem to get through my head as a lift producing device. Lateral resistance, yes. Heck, I've even observed the kayak doesn't "rock side-to-side" as much with the skeg deployed (uh oh hope this doesn't start something new). Are we talking about in a turn with the skeg deployed? That moment when the kayak is turned but the kayak still has a little momentum in the original direction? Or maybe it's just beyond my understanding. I think I'll just shut up and listen. Someone may explain it one day where it all clicks for me. I've been sitting here thinking about this for a few minutes: Is the lift created because in the wind, your real direction is slightly different the where your bow is pointed? Aha! This could be the positive angle? The more skeg exposed, this would generate more lift. AND this would explain why my skeg setting at rest or slow speed is not the same needed at higher speeds (more speed, more lift?). Just wondering, Woody *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert Woodard wrote: > > Dave K wrote: > > > Any airfoil which moves through any fluid, be it air or water, will generate > > "lift" if it has a positive angle of attack (ignoring stalling, > > to simplify things). > > Ok, I understand that part, but how does a skeg get applied at a positive > angle? Doesn't it run in line with the keel (and direction of travel)? [snip] > I've been sitting here thinking about this for a few minutes: Is the lift > created because in the wind, your real direction is slightly different than > where your bow is pointed? Aha! This could be the positive angle? The more > skeg exposed, this would generate more lift. AND this would explain why my > skeg setting at rest or slow speed is not the same needed at higher speeds > (more speed, more lift?). I **think** so, but must defer to those who have used skegs in battle conditions. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert Woodard wrote: > Ok, I understand that part, but how does a skeg get applied at a positive > angle? Doesn't it run in line with the keel (and direction of travel)? > ...<snip>... The above statement explains quite clearly the source of your confusion. Unless you are paddling directly into the wind or directly downwind, the direction of travel is not in line with the keel. A suggestion: Pour yourself a glass of Merlot, put your feet up, and think about this a bit... :-) Dan Hagen *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert Woodard wrote: > Ok, I understand that part, but how does a skeg get applied at a positive > angle? Doesn't it run in line with the keel (and direction of travel)? > ...<snip>... > I've been sitting here thinking about this for a few minutes: Is the lift > created because in the wind, your real direction is slightly different the > where your bow is pointed? Aha! ... Whoops! Sorry about my previous post--I see that you *do* understand this. I simply did not read your post carefully. (Shame on me!) Dan Hagen *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
John Winters wrote: > > ...<big snip>... > > An interesting aspect of skegs comes from their location. Both skegs and > rudders generate lift to offset leeway. A skeg mounted well forward would > work in much the same way as a centerboard on a sail boat producing a net > increase in efficiency when paddling in conditions that produce leeway. A > rather neat aspect deriving (possibly) from a more amidships location comes > in the form of both reducing leeway and weathercocking that, depending upon > the shape of the hull, may not inhibit maneuverability. > ... Very interesting points. I wish we had more information regarding the effectiveness of skegs (and various hull shapes) in reducing leeway, and the implications for efficiency. This may or may not be important for sea kayaks. In principle it seems as though it may be important, but when paddling with others I have not noticed any obvious changes in relative speed among boats with various designs (some with skegs) when encountering conditions that produce leeway. I suspect that this is the sort of thing that could only be detected with very carefully controlled experiments, which is another way of stating that the effects are not large. But maybe I would be surprised. One major difference between skegs and rudders that I have not seen mentioned (in this recent discussion) is the tendency for rudders to lift free in steep seas. I suppose that this is also something that can be attributed to poor design, since it is a function of rudder placement. This can be avoided by mounting the rudder under the hull, and yes (in anticipation of the standard reaction) it *is* possible to mount a *retractable* rudder under the hull. I recently saw one such design that fully retracts. In addition to avoiding "lift out" and surface piercing effects, I was told by the designer that there is another advantage to this type of rudder. He claims that a foil-shaped rudder can create lift more efficiently if it is in line with the boat's keel. The standard stern-mounted rudder does not pivot about its center, but instead swings out to the side. Does this really make a difference? Of course there is a simpler path. "Clean hands, Clean heart, Clean stern" (and clean keel) Dan Hagen *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
>One major difference between skegs and rudders that I have not seen >mentioned (in this recent discussion) is the tendency for rudders to >lift free in steep seas. We have one designer who places the rudder on the side (on Skerries), known as the Southern Viking rudder because he put it on the port and not on the steerboard side and they only appear on Southern Hemishpere kayaks. >...since it is a function of rudder >placement. This can be avoided by mounting the rudder under the hull, He has also modified a Skerry so that the rudder is mounted on the trailing edge of a cut back skeg, all retractable and retractable when striking the bottom. >The standard stern-mounted rudder does not pivot about its center, >but instead swings out to the side. Not necessarily, a number of us design and build them with a bit of balance, that is some of the blade is in front of the hinge line. Alex . . Alex (Sandy) Ferguson Chemistry Department University of Canterbury New Zealand *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
On Oct 18, 22:00, "Robert Woodard" wrote: } Subject: RE: [Paddlewise] skeg ups > Dave K wrote: > > > Any airfoil which moves through any fluid, be it air or water, > > will generate > > "lift" if it has a positive angle of attack (ignoring stalling, > > to simplify > > things). > > Ok, I understand that part, but how does a skeg get applied at a positive > angle? Doesn't it run in line with the keel (and direction of travel)? I can > understand the rudder producing lift, as it can be turned to a positive > direction (left or right). But, a skeg I just can't seem to get through my > head as a lift producing device. > > Lateral resistance, yes. Heck, I've even observed the kayak doesn't "rock > side-to-side" as much with the skeg deployed (uh oh hope this doesn't start > something new). Exactly, lateral resistance. Lateral resistance implies that you have some *sideways* motion to resist. That's what causes the angle of attack that produces the lift. > I've been sitting here thinking about this for a few minutes: Is the lift > created because in the wind, your real direction is slightly different the > where your bow is pointed? Aha! This could be the positive angle? The more > skeg exposed, this would generate more lift. AND this would explain why my > skeg setting at rest or slow speed is not the same needed at higher speeds > (more speed, more lift?). Yes, lift will vary with speed. At a constant angle of attack (not likely) the lift will vary as the square of the speed. -- Bob Myers InteleNet Communications, Inc. Email: bob_at_InteleNet.net 18101 Von Karman Avenue, Suite 550 Phone: 949-851-8250 x227 Irvine, CA 92612 Fax: 949-851-1088 http://www.intelenet.net/ InteleNet Communications is a subsidiary of FirstWorld Communications, Inc. http://www.firstworld.com/ *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Dan wrote; >This may or may not be important for > sea kayaks. In principle it seems as though it may be important, but > when paddling with others I have not noticed any obvious changes in > relative speed among boats with various designs (some with skegs) when > encountering conditions that produce leeway. I suspect that this is the > sort of thing that could only be detected with very carefully controlled > experiments, which is another way of stating that the effects are not > large. But maybe I would be surprised. This problem of "noticeability" pops up a lot. I have found people rather poor at noticing changes in effort etc. Many, many kilometers of paddling hooked up to a B&G Speed Boss just depress me about my ability to detect differences in effort etc. According to some fairly extensive studies on perceived effort done by G.T. Fechner the "Just Noticeable Difference" is one that a person can notice 50% of the time and tends to run about +/- 10%. Not very good if true. Many paddlers believe they can sense smaller differences. I will gladly pass on a rather sneaky test I have used to test paddler abilities to sense differences in effort if anyone has an interest. In any case, I suppose one could calculate the lift etc. of rudders and skegs (maybe I will do this on cold day this winter) since the lift data comes prepackaged in Abbott and Doenhoff "The Theory of Wing Sections". calculating the lift of hulls presents a bigger problem since they have aspect ratios so low as to slither off the scale. In short, they probably don't produce much lift but they can produce measurable lateral drag forces. This would lend itself to easy investigation for anyone interested but I think one can do it mathematically with a bit of thought by adapting existing drag formulas. In fact, I think I can do it with my boat drag formula now that I have an improved low speed transom method. HMMMM. > > One major difference between skegs and rudders that I have not seen > mentioned (in this recent discussion) is the tendency for rudders to > lift free in steep seas. I suppose that this is also something that can > be attributed to poor design, since it is a function of rudder > placement. Not sure this constitute poor design but designers and builders certainly need to address it. Since the water in following waves travels roughly in the same direction as the boat the rudder has less effect on direction anyway. Of course, this applies to any part of the hull and it would seem a mistake to rely upon the rudder as the sole source of directional control in large following waves. It may actually occur that the water in the wave crest moves from stern to bow thus reversing the effect of the rudder. >This can be avoided by mounting the rudder under the hull, > and yes (in anticipation of the standard reaction) it *is* possible to > mount a *retractable* rudder under the hull. I recently saw one such > design that fully retracts. In addition to avoiding "lift out" and > surface piercing effects, I was told by the designer that there is > another advantage to this type of rudder. He claims that a foil-shaped > rudder can create lift more efficiently if it is in line with the boat's > keel. The standard stern-mounted rudder does not pivot about its center, > but instead swings out to the side. Does this really make a difference? I cannot imagine why. Woody asked about "lift" and skegs and I think that got answered rather nicely. I would add that every time the stern wiggles due to a stroke the skeg develops lift or drag to offset the turning moment. Alex mentioned some variations on rudders. North Americans rarely see these variations and tend to think that the flat plate type typifies all rudders and draw their conclusions based on this assumption. Rather a shame because a "good" rudder really does make a huge difference in controllability. Dave asked about the best airfoil and , yes, we do have lots of information on this. I see the NACA 0012 section most often on sailboats. I have a bit of partiality to the NACA 2006 as providing a better lift to drag ratio but I know some who would argue for laminar flow blades. The section one chooses depends upon objectives. For aggressive steering the 0012 delays stall best while for subtle steering techniques a laminar flow section (NACA 16-006) might work better. The laminar flow section should work better on skegs. Dan also wrote; >A suggestion: Pour yourself a glass of Merlot, put your feet up, and >think about this a bit... A good suggestion even if you don't feel like thinking. :-) Cheers, John Winters Redwing Designs Web site address, http://home.ican.net/~735769 *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:04 PDT