Talk:High-performance sailing/Archive 2

Revised treadmill experiment
We want to demonstrate that a device can sail or propel itself dead downwind faster than the wind. We decide to use a treadmill. We assume a tailwind of 10mph and so we set the treadmill at 10mph and we leave it flat - no incline required. We leave the electric fan turned off because, at 10mph, there is no apparent wind. We put out miraculous model on the treadmill and hold it there with our finger so it neither moves forward or backward. It's wheels are turning and they're geared to the model's propeller. We remove our restraining finger. Does the device accelerate forward on the treadmill and continue to move forward? That's the experiment I want to see. I know the result and I am offering long odds to all comers! Paul Beardsell (talk) 14:17, 6 June 2010 (UTC)


 * That is ancient history.  demonstrates progress dead downwind faster than the wind in real conditions, not on a treadmill.--Gautier lebon (talk) 08:38, 7 June 2010 (UTC)


 * No! It is a hoax. There are ten-a-penny hoaxers with gadgets and equipment AND WEB SITES peddling their perpetual motion machines. It's a hoax!  Energy from nowhere.  If their argument were true there would be no limit to the downwind speed achievable!  Paul Beardsell (talk) 09:03, 7 June 2010 (UTC)


 * It is not energy from nowhere. The energy comes from the wind.  There is a limit to the speed that can be achieved: that limit comes from the friction on the surface and the resistance from the induced apparent headwind.--Gautier lebon (talk) 12:26, 7 June 2010 (UTC)

The problem with the YouTube video
You're on the model, and the model is on the treadmill. We imagine a tailwind of 10mph so we run the treadmill at that speed. What would the real-life apparent wind be to (mini-)you? Zero. So why is there an electric fan behind the treadmill? [I do not refer to the fan on the model, but the fan on the ground behind the treadmill.] Assume further that the machine works as desribed. Now we are travelling faster (say 12mph) than the wind, downwind (10mph, say). [That is the claim!] What should (mini-)you experience on the model on the treadmill? A headwind of 2mph! So the electric fan on the floor behind the treadmill should in reality be in front of the treadmill providing the 2mph headwind. That is NOT what the YouTube video shows! Paul Beardsell (talk) 09:00, 7 June 2010 (UTC)


 * Forget the YouTube video. That is ancient history.  The relevant material is at .--Gautier lebon (talk) 09:12, 7 June 2010 (UTC)


 * So you agree the YouTube vid proves nothing? In which case the only people who say they've made a nonsense of thermodynamics are the hoaxters themselves? And some here.  Paul Beardsell (talk) 09:33, 7 June 2010 (UTC)


 * No, I did not say that. I said that the You Tube video has been superseded by more detailed and convincing evidence.--Gautier lebon (talk) 12:25, 7 June 2010 (UTC)

Perpetual motion
Another way to demonstrate the perpetual motion nature of this is to ask what the theoretically maximum multiplier of the downwind speed is. Downwind 10mph, what 's the limit of the vehicle's speed? No limit according to the reasoning presented! Paul Beardsell (talk) 14:33, 6 June 2010 (UTC)


 * That is not correct, of course there is a limit. But is is not easy to compute because it depends on many factors. As the article clearly states, the limit comes from the friction of the hull (or wheels or runners) on the surface, the resistance induced by the apparent head wind and the efficiency of the device (sail or propeller) that captures the energy from the wind.  According to, a dead downwind speed of 3 times wind speed is possible. That seems reasonble when you look at actual performance data from iceboats.  Please look at the cited references before concluding that things are impossible which are in fact well known to be routine to people who have experience with iceboats, sand yachts, and high-performance catamarans.--Gautier lebon (talk) 09:15, 7 June 2010 (UTC)


 * No, limits come not only from friction. E.g. the carnot cycle shows the absolute limit of a petrol engine as being far far less than 100%.  We are not talking friction.  There has to be a theoretical limit to the maximum downwind speed achievable by this contraption of yours.  I say it is less than the windspeed.  You say it is unlimited except by friction.  Wow.  Paul Beardsell (talk) 09:36, 7 June 2010 (UTC)


 * What does the carnot cycle have to do with this? We are not burning fuel here.  It is not I that says that it is unlimited, it is a number of cited sources, which include actual observed runs.  Whereas you provide no citations, only your personal opinion. Surely this is not how Wikipedia is supposed to progress?--Gautier lebon (talk) 12:24, 7 June 2010 (UTC)


 * Actually, the answer is simple: In a purely theoretical sense, there's no limit, but in practice, materials always limit you.  It's like asking questions about the leverage provided by a lever.  What is the theoretical maximum multiple of the speed at which one end of a lever moves that the other end moves at?  There isn't one.  What is the *practical* maximum?  Depends on your materials.  But, no, there is not a theoretical limit, because the limitations are purely a question of materials. Wikiseebs (talk) 18:31, 10 June 2010 (UTC)

Sailing faster than the wind, but at an angle?
Also, those who say that one can sail a boat directly downwind faster than the wind by not proceeding directly but at an angle are WRONG. A floating baloon still gets to the directly downwind point before you no matter how you tack. You tack a modern sailboat because it is quicker to do that and gybe to get to a point directly downwind than trying to do it directly but that's still not quicker than the balloon. Paul Beardsell (talk) 14:33, 6 June 2010 (UTC)


 * It is quite amazing that you come to such a strong conclusion against overwhelming empirical evidence (ice boats, Amarica's Cup multihulls, sand yachts). The whole beauty of the idea of sailing faster than the wind is that it seems counter intuitive, to run against the 'laws of physics' (It doesn't - if it would, the topic would be discussed on the front page of the New York times!). MrBeanBob (talk) 23:56, 7 June 2010 (UTC)


 * As I make perfectly plain below, of course you can travel faster than the wind. But by keeping the wind on your quarter.  Assuming a no loss of speed gybe you still get to the downwind point after the floating balloon, despite your speed over the ground.  Paul Beardsell (talk) 12:03, 8 June 2010 (UTC)

Sure, you can travel at 1.2 x the speed of the wind, downwind, in a modern sailing dinghy, but at a considerable angle to the wind, the distance you have to travel to get to a point directly downwind is considerable more than 1.2 times the direct distance! It's quicker if the angle is 60degs or less because the direct downwind sailing speed is at best 0.6 the wind speed. But quicker is the free floating balloon. Paul Beardsell (talk) 14:36, 6 June 2010 (UTC)


 * Please read the cited references, as others have. When you work out the trigonometry, you can indeed have downwind VMG greater than windspeed, and thus arrive faster than the baloon.  You deleted numerous reliable sources that say that.--Gautier lebon (talk) 08:39, 7 June 2010 (UTC)


 * No! No source I have deleted has said that. You (and others) may have interpreted them as saying that but NO THEY DO NOT SAY THAT.  They DO say they can travel faster accross the ground than the windspeed (and I do not deny it - having done it myself) but they DO NOT say that the VMG towards the directly downwind speed is greater than windspeed.  I tell YOU, *YOU* work out the trig.  The angle and the speed are inter-related by the inequality (speed across the ground)/cos(angle to the wind) < (wind speed).  If the angle and the speed break that inequality then they are an invalid combination.  Sorry! You cannot beat the balloon. Paul Beardsell (talk) 09:07, 7 June 2010 (UTC)


 * Paul, please read the source before saying that it does not say what it actually says. The trigonometry is indeed worked out, and anybody can see how it works, if you take the time. What is unclear is whether the theoretical trigonometry can be achieved in practice, because of resistance, inefficiency, etc.  The cited sources give multiple examples of verified cases where it was achieved in practice, not least during the America's Cup.--Gautier lebon (talk) 09:18, 7 June 2010 (UTC)


 * America's Cup? No. I followed the refs and could not see the assertions claimed. It was WP:SYN by you or another WP editor.  I suggest the downwind point was not DIRECTLY downwind.  The course marks are set and then the wind changes, they do not change the marks.  Even in top flight sport the basic laws of Physics remain unbroken.  Strange that!  Paul Beardsell (talk) 09:31, 7 June 2010 (UTC)


 * Actually there were direct quotations from the people on the boats to the effect that they went downwind faster than a balloon. Again, you cite laws of physics, but provide no citation nor any detailed explanation of why some particular law would be broken.--Gautier lebon (talk) 12:21, 7 June 2010 (UTC)


 * I saw nothing in the quote you provided to say any such thing. They said they went faster across the water than the wind, but they did not say they beat the wind to a point directly downwind.  Paul Beardsell (talk) 12:04, 8 June 2010 (UTC)


 * You have not read the citations carefully enough. They do say that progress to the downwind mark was faster than the wind.--Gautier lebon (talk) 11:32, 11 June 2010 (UTC)

Disputed tags
What I dispute is the assertion made in the article and here that it is possible to sail downwind faster than the wind to reach a point directly downwind faster than a free floating balloon. This is impossible. The vector diagrams are incorrect in that whereas they presume to tell us that a sailing boat can travel at 1.2 times the speed of the wind through the water (or an ice yacht can travel at 5 times the speed of the wind over the ice) those making the argument fail to note the angle to the wind that must be travelled. Given zero friction, to travel at twice the speed of the wind downwind you must travel at an angle of 60 degs to it (cos 60 = 0.5). To get to a point directly downwind you have to gybe half way and you get there, with your 100% efficient yacht, at precisely the same time as the free floating balloon. Paul Beardsell (talk) 15:06, 6 June 2010 (UTC)


 * Your trigonometry is simply incorrect, and you have deleted the graphic that shows the correct trignometry. I find this most disappointing.--Gautier lebon (talk) 12:47, 7 June 2010 (UTC)

Why, therefore, you may ask, do sailors bother to travel at an angle to the wind downwind? Because their boats and sails are so abysmally inefficient directly downwind. Sailing with your wind on the quarter is quicker than directly downwind, but still SLOWER than the free floating balloon to reach a point *directly* downwind. Paul Beardsell (talk) 15:06, 6 June 2010 (UTC)

Hence the "disputed" tag at the beginning of the article. Paul Beardsell (talk) 15:06, 6 June 2010 (UTC)

Further I strongly suggest that the cited refs do not support the assertion that in the America's cup downwind progress was quicker than a free floating balloon. If it is WP:SYN I cannot see how it was synthesized. But that or WP:OR neither are acceptable. Paul Beardsell (talk) 17:05, 6 June 2010 (UTC)


 * The only OR here is your own: you say that things that are said by relilable sources are impossible, but you do not provide any source that supports your assertion. We have been there before, I find it puzzling that we have to have the same discussion over and over again when it suffices to read the cited sources to understand why it is indeed possible to have a downwind VMG greater than windspeed.--Gautier lebon (talk) 08:41, 7 June 2010 (UTC)


 * No the onus is the other way. You want to include something then if I challenge it you must provide WP:VSs. Not just some self promoting web site from some hoaxters with corporate sponsorship. No!  SciAm or New Scientist would do me.  There is no onus on ME to say why what you say is wrong.  You want to include material, you must support it.  Please read WP:VS, WP:OR and WP:SYN.  Thanks.  Paul Beardsell (talk) 09:11, 7 June 2010 (UTC)


 * Indeed, but there were extensive discussions at an earlier stage, and numerous Wikipedia editors agreed that the citations provided were reliable and so the material was suitable for inclusion in Wikipedia. You have a different view, and I do think that it is appropriate to discuss that on this page, and to include a "disputed" tag in the article.  But I don't think that it is appropriate do delete what represents a lot of work by many people until we have further dicussed it on the discussion page.--Gautier lebon (talk) 09:23, 7 June 2010 (UTC)


 * I agree. And I leave unobjectionable but questionable material on the page.  But material with irregular citing of the hoaxters to support the hoaxters' claims, the WP:SYN citing of refs which DO NOT support the assertions made in the text, that comes OUT. It is not worthy of remaining in the pedia pending discussion.  I believe WP policy suports me here.  As does the (lack of) quality of the argument here resulting.  Paul Beardsell (talk) 09:40, 7 June 2010 (UTC)


 * But you have added a flagrant OR, namely that a boat cannot reach the downwind mark faster than a balloon. You have deleted all the citations showing the contrary, and you have added that totally unsupported statement.  Surely this is not how Wikipedia is supposed to be edited?  If you have a citation to support your statement, please provide it.--Gautier lebon (talk) 12:49, 7 June 2010 (UTC)


 * Remove it if you must, but I added it to allow the unsubstantiated sentence preceding to remain. It goes, that goes. Paul Beardsell (talk) 12:06, 8 June 2010 (UTC)


 * The previous sentence is not unsubstantiated, it is supported by numereous citations.--Gautier lebon (talk) 11:34, 11 June 2010 (UTC)

Removed section
I just removed the whole section on sailing downwind faster than the wind. It's all nonsense. I did try fixing it a bit but the only refs which actually supported the argument were to this talk page. The rest of it is to a HOAX and a set of links to perpetual motion machines. Paul Beardsell (talk) 17:19, 6 June 2010 (UTC)


 * That is your assertion, again not backed by any source. Whereas the material that you deleted was based on reliable sources.  Please do not substitute your original research for verifiable citations.--Gautier lebon (talk) 08:44, 7 June 2010 (UTC)


 * Not reliable as per WP:VS. Paul Beardsell (talk) 09:28, 7 June 2010 (UTC)


 * That is your opinion, not the opinion of the many other editors who worked on this article.--Gautier lebon (talk) 12:17, 7 June 2010 (UTC)


 * There is much of merit in the article. Those editors have not provided questionable sources for the material they have added. The material I have removed is supported only by the claims of the hoaxters/heroes themselves on their own website. Not WP:VS.  Paul Beardsell (talk) 12:10, 8 June 2010 (UTC)


 * This is not correct. You removed a great deal of material that was supported by perfectly reliable citations.--Gautier lebon (talk) 11:36, 11 June 2010 (UTC)

Please help, aeronautical engineers
The "propeller machine" needs to be explained. If sustained faster speed (rather than quick "hops") is possible, then it can be modeled and an expert can explain it. If the wheels and propeller alternate as prime mover, then how is equilibrium reached? Does the craft ride on a pressure wave? Do the air vectors form a standing wave in relation to the craft? Storing momentum and then accelerating quickly is cheating. What minimum speed over what minimum distance proves the novelty of the case? Anthony717 (talk) 17:50, 6 June 2010 (UTC)


 * It is explained, in several different ways, on the talk pages. And it is demonstrated at .  There is no alternation, it is a steady state situation, in which sufficient energy from the wind is captured to allow downwind progress faster than the wind itself.--Gautier lebon (talk) 08:47, 7 June 2010 (UTC)


 * This claim is unsubstantiated. Paul Beardsell (talk) 09:22, 7 June 2010 (UTC)


 * There is no need for WP to explain the unexplainable. Or to attempt to. We can just wait for a reputable journal such as Scientific American or New Scientist to report that it works and reflect their report here. This is *not* Popular Mechanics, we do not need to speculate, this is an encyclopedia.  So until then we need do nothing and, even then, there is no urgency.  Paul Beardsell (talk) 22:30, 6 June 2010 (UTC)


 * But for those who ache to be told it isn't a hoax, its a hoax! Paul Beardsell (talk) 22:30, 6 June 2010 (UTC)


 * Furthermore, aeronautical engineers are in particular not required. The credibility of an engineer can only be damaged by endorsing a perpetual motion machine. Paul Beardsell (talk) 22:30, 6 June 2010 (UTC)


 * Again, this is your unsupported assertion.  proves otherwise. It is not a hoax.--Gautier lebon (talk) 08:47, 7 June 2010 (UTC)


 * Perhaps, perhaps not. But "unsupported assertions" may appear on a Talk page. They may NOT appear in the encyclopedia themselves. Any assertion in WP itself which is challenged must be supported by WP:VS or face removal.  That is WP policy.  The hoaxters web site does not qualify as WP:VS.  I note even they shy away from using the word "proof" and that the NLASA does not (yet) support the claims.  But NLASA is not NASA so who cares one way or the other!  "NLASA says Second Law of Thermodynamics is invalid" is a headline we won't see anywhere reputable soon.  Paul Beardsell (talk) 09:51, 7 June 2010 (UTC)


 * One feature of all hoaxes is that it must take some people in! I know this is not a compelling argument.  But conservation of energy is something which nearly all people believe in.  Paul Beardsell (talk) 09:27, 7 June 2010 (UTC)

You keep talking about conservation of energy, but you never explain why this is violated. Once again, the energy contained in the wind is very large. An efficient device such an an iceboat can capture more than enough energy to overcome the frictional resistance (from the surface and the apparent headwind) to go 5 or more times faster than the wind. When you work out the trigonometry, it is obvious that downwind VMG is greater than wind speed. There is no violation of conservation of energy or any other physical law. Please provide a citation that says otherwise.--Gautier lebon (talk) 12:16, 7 June 2010 (UTC)


 * You continue to get this the wrong way around. What must be supported by WP:VS is that which is IN the article. Not so supported? It can be removed. I removed it. The only sources given for the claims are those of the claimants themselves. It would be helpful were I to provide refs for my assertions here but do not have to: This is not a pedia page it's a talk page. Paul Beardsell (talk) 12:13, 8 June 2010 (UTC)


 * Again: you deleted material that WAS supported by reliable citations. And you did that on the basis of assertions that cannot be proved (such as violation of conservation of energy) because those assertions are incorrect.--Gautier lebon (talk) 11:38, 11 June 2010 (UTC)

More unsupported text removed
I have removed this:


 * Other sailboats (such as the 18ft Skiff) can make good downwind at speeds faster than the wind. Indeed, it can be seen from the polar chart for the 18 ft Skiff that it can make good about 12 knots downwind at a windspeed of 10 knots, by jibing back and forth at about 140 degrees off the true wind.   The polar chart in Figure PS1 of the cited book High Performance Sailing'' shows that boats that were sailing in 1996 were able to make good downwind at about 1.5 times the speed of the wind.

''

I followed the 1st citation (the yoavraz2 one). It does NOT say VMG is greater than windspeed. It says you travel at an angle to the wind and sometimes at a speed greater than windspeed across the earth, but it does NOT say ANYWHERE that VMG > windspeed. Remember VMG is speed towards the directly downwind point, not speed across the earth. Further, an interpretation by a WP editor of a diagram quite possibly not drawn to scale or maybe exaggerated in order to illustrate an argument is not a WP:VS verifiable source.

Paul Beardsell (talk) 08:21, 7 June 2010 (UTC)


 * Please read the book before saying that it does not way what it does indeed say. It is not an interpretation of a diagram, it is a direct summary of what the diagram shows, and what the text of the book itself says in several places.  The book is easily available: please go to a library and read it (or buy a copy and read it) before challenging the material in question.--Gautier lebon (talk) 08:49, 7 June 2010 (UTC)


 * You obviously have the book. You can quote from it, therefore? Even so, if I find a book that challenges the laws of thermodynamics does that mean I can make outlandish claims on the thermodynamics page of an ENCYCLOPEDIA.  Sailing DWFTTW would be in contravention of 2nd law of thermodynamics / conservation of energy, by the way.  Paul Beardsell (talk) 09:25, 7 June 2010 (UTC)


 * I did quote from the book, but you deleted the quotes! Please explain how the second law of theormodynamics or the law of conservation of energy are violated. To do that, you need to show that the energy used by the boat as it progresses is greater than the energy that it captures from the wind.  Please produce a citation that gives the equations and calculations.  I (and the other editors) have produced citations of actual observations of the phenomenon.  Please produce a citationt to support your bald that all those references are wrong or hoaxes.--Gautier lebon (talk) 12:13, 7 June 2010 (UTC)


 * Please feel free to re-add anything you genuinely feel is WP:VS supported which I have removed erroneously. But as a discussion has opened up you do, I think, need to specifically justify that, here, when you do.  Paul Beardsell (talk) 12:14, 8 June 2010 (UTC)

factual Dispute initiated and sustained by PB
This article was developed collaboratively over a period of many months. As seen above, there was extensive discussion and a stable version was finally produced. Recently, Paul Beardsell (PB) has asserted that the article is incorrect. This implies that all the people who worked on the article made mistakes. Of course that is possible and the matter should be discussed. But I do not think that we are going about this the right way, as explained below.--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)

procedural issues
According to my understanding of Wikipedia policies, PB should have tagged the article as being the subjet of a dispute (which he did) and then discussed the matter on the discussion page. This is not what PB did. PB proceeded to delete material that was supported by citations, arguing that the citations were wrong. PB goes so far as to dispute information derived from a book by Bentwaithe, a known authority (the book is published by a reputable publisher). Surely this is not compatible with Wikipedia policies.--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)

Worse, PB added to the main article the statement "[a boat's downwind progrss] remains slower than the time taken for a free floating balloon to travel the downwind track directly". PB does not provide any citation to support this assertion. It is thus Original Research that cannot be allowed to remain in the article. Further, the assertion is directly contradicted by the citations that PB deleted.--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)

substantive issues
PB asserts that downwind VMG cannot exceed the speed of the wind, because that would violate the law of conservation of energy. He provide no citation to support that assertion. As explained above, there is no violation of the law of conservation of energy.--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)

PB's hypothesis, if you work out the trigonometry, means that VMG must be less that 1/cos(gamma) times wind speed, where gamma is the angle between dead downwind and the course (that is, gamma = 0 if dead downwind). In terms of course with respect to the upwind mark, this means that VMG, in terms of multiples of wind speed, would be limited to 1 for 180-degrees (dead downwind), 1.1 for 155, 1.22 for 145, 1.41 for 135, 2 for 120, 2.9 for 110, 3.9 for 105, 5.7 for 100, and infinite for 90. Of course infinite is not possible, because friction and the limits of how close the boat can sail to the apparent wind will come in. So PB's hypothesis is that VMG, as a multiple of wind speed, must be less than the minimum of the numbers given at the now deleted section Sailing_faster_than_the_wind#Speed_made_good and the numbers given above. But that hypothesis is falsified by published polar charts and by information on iceboats, which can go 5 times faster than the wind while sailing lower than 100 degrees off the wind. PB claims that all those citations are unreliable and incorrect. But the fact remains that there are citations that contradict PB's hypothesis. Also, there should be a physical explanation to support PB's hypothesis: what physical phenomenon limits to boat to VMG=1? As noted above, it cannot be the wind, because what counts is the apparent wind, and that would not limit VMG to 1. And it cannot be conservation of energy. Please also note the following quote from ThinAirDesigns, who is apparently a graduate student in aeronautics: "Most involved here in these discussions acknowledge that it's possible to steady state sail a traditional sailing rig at a fixed angle to the wind where the downwind VMG of the craft is greater than 1x windspeed (even 2x, 3x ...). Those who do not agree with this should review the data collected by NALSA (nalsa.org) on the topic." (see Talk:Sailing_faster_than_the_wind#DDW_faster_than_the_wind_thought_experiment). As stated on their web site, several students, and a professor, have built a device that has proven that it is possible to progress dead downwind faster than the wind, see. So, if PB's hypothesis is correct, then (1) a lot of people have gone to a lot of trouble to fabricate false or misleading reports and (2) many people, including graduate students and professors, have been fooled into believing the impossible. Further, as an experienced sailor stated:--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)


 * VMG: Let's be clear. VMG is the speed towards your target point, not speed over the ground.  GL and ThinAirDesigns seem to change the definition of this term from argument to argument, and this has led I believe to GL's misinterpretaion of Bentwithe (sp?).  Boat speed can be greater than wind speed, yes.  VMG can be greater than boat speed, yes, but not for all desired points!  When the desired point is a point directly downwind, VMG (i.e. towards that directly downwind point) is never greater than windspeed, but boatspeed over the ground (i.e. currents aside, thru the water) may exceed windspeed while attempting to get to that dead downwind point.  The angle at which you travel means however that (waterspeed)/cos(angle travelled to true wind) < (true wind speed), and that allows the free floating balloon to beat you, every time.  Faster than windspeed has never ever been denied.  What is denied is that you can independently choose your speed and your angle as implied by a diagram I deleted from the article.  Paul Beardsell (talk) 10:36, 8 June 2010 (UTC)


 * What we are discussing here is downwind VMG, that is, velocity made good in the dead downwind direction (in vector terms, the component of the speed vector that points in the downwind direction). We are not talking about VMG in any other direction. You again assert that downwind VMG cannot exceed wind speed.  But Bentwaithe says otherwise, and provides polar charts that show otherwise.  The data from the America's Cup also shows otherwise.  The diagram you deleted did not show that you can independently choose your speed and angle.  It showed the relation that MUST hold between speed and angle, given the laws of trignometry.  The question then is whether or not those particular combinations can be achieved in practice. Again, data provided in several references (all deleted by you) show that indeed those combinations can be achieved in practice by iceboats, sand yachts, and some high-performance sailboats.--156.106.202.4 (talk) 13:29, 8 June 2010 (UTC)


 * If your book says that, it is wrong. If the data says that, it is wrong. Yachting's achievements are many but overthrowing classical mechanics is not one of them.  See new section below.  Paul Beardsell (talk) 15:17, 8 June 2010 (UTC)


 * Nobody is overthrowing classical mechanics. The issue is that you are misunderstanding and misapplying the relevant physical concepts.  Many of us have tried to explain this to you, see below.--Gautier lebon (talk) 15:44, 10 June 2010 (UTC)


 * "VMG, in terms of multiples of wind speed, would be limited to 1 for 180-degrees (dead downwind), 1.1 for 155, 1.22 for 145, 1.41 for 135, 2 for 120, 2.9 for 110, 3.9 for 105, 5.7 for 100, and infinite for 90" thanks for working those out. Very handy. So... I need to find a boat that will go faster than 1.41x TWS @ 135 degrees off the wind. Many boats can do that."


 * Name the boat. Paul Beardsell (talk) 10:26, 8 June 2010 (UTC)


 * Any iceboat. Look at the NALSA web site.--Gautier lebon (talk) 15:37, 10 June 2010 (UTC)

dispute: proposed resolution
I propose that we revert the article back to where it was before PB started editing it, but with a "diputed tag" and then use this discussion page to agree what, if any, modifications are needed.--Gautier lebon (talk) 09:38, 8 June 2010 (UTC)

The standard way forward
There is no need to personalise this. Nevertheless I stand by what I have done. I have removed text fromm the article not properly supported as per WP:V. Several citations were to thought experiments on this Talk page! Others were to the web site of the faster than the wind downwind device. It is those questionable assertions (to be polite) which I removed from the article. Also removed were those assertion resulting from WP:SYN and WP:OR. This is agreed (in part at least by GL) and others have said some of the text should not have been included. The GL-proposed solution is not the WP way. If you want to reinclude the some text then please DO SO, FEEL FREE, I WILL NOT OBJECT if it is either obviously non-controversial or if it is supported by what is obviously acceptable as per WP:VS. The WHOLESALE reversion of my edits would seem to imply that I have done nothing in value. Just do it on a one by one basis, being careful to state OBJECTIVELY and to back this up. Paul Beardsell (talk) 10:13, 8 June 2010 (UTC)

For example. "The XYZ Group claimed 33 remember 2020 that they had achieved faster than the wind downwind speeds.[3rd party citation]" is acceptable. What is not is "On 33 remember 2020 FTTWDW speeds were achieved.[XYZ Group]" Paul Beardsell (talk) 10:13, 8 June 2010 (UTC)


 * That might be a path forward, but it would result in the restoration of the entire section on VMG, which you have, so far, violently objected to. Let's give others a chance to comment, and maybe we can then agree a path forward.--Gautier lebon (talk) 10:16, 8 June 2010 (UTC)


 * Is is a standard way forward. You replace anything you like but only if not saying claims are facts, and as a VERY STRONG preference using 3rd party citations, not from the parties themselves. Please see WP:V.  Paul Beardsell (talk) 10:22, 8 June 2010 (UTC)

I too was involved in lengthy discussions on many of these points at Talk:Sailing. I was sceptical about the physics, as well as the references and the WP:OR. At one point I too tried to clarify the terminology, saying, "Let us agree at least that we are talking about sailing downwind faster than the wind, not just sailing faster than the wind, and also that we are not talking about coasting downwind faster than the wind immediately after a very fast beam reach."
 * The physics
 * In the end it was this discussion above that convinced me that we don't have a fundamental problem with the physics, or any requirement for previously-stored energy etc. Alpha Ralpha Boulevard's spaceship-and-gun model described above has the true wind at 90 deg to the boat and so there is no progress downwind. However, my contribution to that model shows that it is the boat's ability to sail close-hauled (while still overcoming friction and drag) that is the limiting factor. (Paul B, you mention above that there must be a limit, or we probably have 'perpetual motion' - that is it). It is only one more step to imagining the true wind at, say, 135 deg, the boat accelerating until it is again close hauled 10 or 20 deg off the apparent wind, and all the physics is in place for VMG downwind greater than the true wind speed, with gybes to reach a downwind point. All this talk about iceboats, sandyachts and spaceships on rails comes about because real sea-going boats rarely can sail much better than 45 or 40 deg off the apparent wind. Some modern ultralight catamarans may be able to do this in calm water.


 * The references, the OR and the SYN
 * Here I have to agree more with Paul B. Some of the sourcing here was not up to standard, and it needs to be. We cannot say that all this trigonometry, thought experiments, models and then real polar diagrams are 'just connecting obvious facts'. There is far too much synthesis required for some of the statements that have been removed. If all this is true and downwind VMGs are being recorded greater than windspeed, then it won't be long before they start appearing explicitly described as such in reliable secondary sources. Until that happens, I think we have to be patient and wait for these sources to appear. In the meantime, the title of this article is 'Sailing faster than the wind' and there is plenty that is well-sourced to say about that in general before getting into downwind VMGs greater than windspeed. I have not reviewed all the sources and so can't say how much of what we had was well-sourced, but some of it certainly was not. --Nigelj (talk) 13:09, 8 June 2010 (UTC)


 * Nigel: I can accept most of your suggestions. Regarding "it won't be long until they start appearing explicity described as such in reliable secondary sources", sorry, but this is all so obvious to the people who sail these machines that they don't see the need to write it up.  That is also the reason why there aren't articles in refereed physics journals: it is too obvious to be published in a referred journal.  I've scoured for write-ups, and found the Bentwaithe book and the NALSA web site. I agree that those are not exactly secondary sources, but it seems to me that they are close enough.  In particular Bentwaithe summarizes data regarding various boats, so that part of his book is a secondary source.--Gautier lebon (talk) 13:34, 8 June 2010 (UTC)


 * Yes. You are going to have a hard time finding a paper in a physics journal on the revolutionary topic "Mixing red and yellow paint sometimes produces orange paint." Wikiseebs (talk) 18:53, 10 June 2010 (UTC)


 * There are other reasons why something doesn't get published in refereed journals. E.g. they're laughably wrong.  Paul Beardsell (talk) 14:59, 8 June 2010 (UTC)


 * Yes, but this is not one of those situations.--Gautier lebon (talk) 15:45, 10 June 2010 (UTC)

For the record
As this discussion becomes increasingly difficult to follow and no way forward emerges, I would like to make the following statement for the record: In my opinion the article version of 6 May 2010 did not contain (1) arguments violating the laws of physics, (2) any Original Research, nor (3) any not-permitted Synthesis. The many references amply supported the main - and intriguing - arguments that (a) velocities over ground greater than wind speed are possible and that (b) VMGs towards the dead-downwind direction greater than wind speed are possible (faster than the air baloon). Nevertheless a more concise text seems possible and desirable. (Please do not edit this paragraph.) MrBeanBob (talk) 21:44, 8 June 2010 (UTC)

I have been reading these arguments that Paul Beardsell has been making. When I was an engineering student at a major engineering university, I took a course in statics. We worked this exact problem. You get an extra vector when sailing at an angle to the wind. That vector adds to your speed. There are no "conservation of energy" requirements that says a vessel cannot tack back and forth and beat a boat (or balloon) sailing directly downwind. If the vessel has enough sail and enough keel and does not have too much friction, it can get lots and lots more speed. It is difficult for sailboats to do this, (some can, but just barely), but it is easy for ice boats to do it. Ice boats do it all the time, with room to spare. I suggest Paul Beardsell do some googles on ice boat sailing. Some of the ice boat forums address this exact issue. To solve this problem in a scientific (engineering) way, one needs to draw vectors. This is exactly what the author Gautier lebon has done. Paul Beardsell needs to take a class in Statics so he can understand these vector diagrams. Thousands of engineering students taking statics have solved this very problem. Thousands of ice boat racers have proven that an ice boat tacking back and forth beats an ice boat going straight downwind. It is a common ice boat race, then they switch positions and get the same results, with identical ice boats and closely matched pilots. Any good book on sailing theory will address the issue. There is no scientific question that Gautier lebon's assertions are correct here. The theory is correct and the experiments back it up! Revert the article to Gautier lebon's assertions and get rid of the factual accuracy is disputed. There is no dispute amongst engineers who are informed on this issue. What makes it hard to understand, is the correct answer is not intuitive in this case. To understand it, you need to understand the vectors, the sail and the keel. Pontificating on some "law of energy conservation" isn't the right way to understand the issue. The sail converts the wind into the force necessary to propel the craft. The keel translates some of that force into speed in the desired direction and dumps the rest off into friction and the vectors allow us to obtain theoretical numbers on how a "perfect" boat would behave. Good work Gautier lebon! —Preceding unsigned comment added by Aviatorpilotman (talk • contribs) 03:58, 12 June 2010 (UTC)


 * Hear, hear! I think we have a clear consensus here. There's no need to list all the people who agree against the one who doesn't. Let's fix the article. --Nigelj (talk) 10:30, 12 June 2010 (UTC)


 * Agreed. Whaleswatcher had already reverted the edits by Paul Beardsell.  I will now remove the disputed tags and add a warning so that, hopefully, we will not get into this sort of conflict again.--Gautier lebon (talk) 13:39, 12 June 2010 (UTC)

There may be some useful ideas from all this PB controversy. When an uninformed reader come in he may ask himself a question such as: If a sailboat can outsail the wind by tacking on a downwind course, why then do they proceed on a downwind course and put up their spinakers? And they may assert the same arguments as PB did. You may wish to address these ideas. I also think some more emphasis on how important the keel is would be useful. Without a keel (a flatbottom sailboat), the sailboat could not do what it does. In my thought experiement I envision a sailcraft on a set or RAILS. A top rail and a bottom are laid at an angle to the wind, say for a 2 mile course. The top rail keeps the boat from tipping over. The rails are well oiled and have little friction. In a sailboat, the keel acts as such a "rail".


 * Re why put up a spinnaker: (1) some boats can and do tack downwind even with a spinnaker, but of course only if they cannot accelarate enough so that the apparent wind is forward of the beam; such is the case for most keel boats. (2) Most sail boats, in most conditions, cannot accelerate enough so that the apparent wind is forward of the beam; in that case, there isn't that much to gain from tacking downwind, so people don't bother, except in tight regattas. But you are correct that this should be explained, I've added it to the fallacies.--Gautier lebon (talk) 12:40, 13 June 2010 (UTC)

I have a statement regarding the propeller driven cart. A propeller is NOT a sail!! A propeller "tacks" through the wind! It has angles on its blades. Although I don't claim to completely understand their clever contraption, I don't think it is "sailing". Sailing uses sails, not props! The prop can use the same extra vector that a sailboat gets when it sail off the wind. I question whether such a device should even be in an article such as this. It is interesting but a bit distraction from the main points. Perhaps it needs it's own article? —Preceding unsigned comment added by Aviatorpilotman (talk • contribs) 18:32, 12 June 2010 (UTC)


 * Hello Aviatorpilotman. One of the very common misconceptions regarding the propeller driven cart is that it is somehow using it's airfoils different than a common sailing rig on a broad reach does.  There are many ways to show that this isn't true and that the propcarts airfoils are nothing more than the common sail on a broad reach of a smaller radius than folk are normally accustomed to seeing. If I  may, here is a link to an animation that might help you visualize this.  http://www.youtube.com/watch?v=UGRFb8yNtBo   The kicker here is that most folks (even sailors) hold the belief that a traditional sailing rig always acts as a turbine (slowing down air relative to itself) while in fact there are many points of downwind sail that a traditional rig acts as a propeller (*accelerating* air relative to itself).  It's just one more of the many counterintuitive aspects of sailing that this topic has brought to the surface. ThinAirDesigns (talk) 19:02, 12 June 2010 (UTC)


 * As I understand it, it is the same as the difference between a rotating wing flying craft (helicopter or autogyro) and a fixed wing flying craft (airplane). Boats usually used fixed sails.  The dead downwind cart uses rotating "sails".  Theoretically, one could use rotating "sails" on points of sail other than dead downwind, see .  I agreee that most people would not consider a rigid propeller blade to be a sail.  But from the functional point of view it is, in this context.  Recall that old windmills used blades that were in fact very similar to conventional sails: cloth panels streched over a wooden frame.  Modern windmills use propellers, but the function is exactly the same: to catch the wind, deflect it, and generate energy from that deflection.  This is exactly what a conventional sail does, and what the propeller on the dead downwind cart does.--Gautier lebon (talk) 13:02, 13 June 2010 (UTC)

Question for Gautier lebon: In the article drawing labeled "Downwind", is the line labeled "sin(beta)" a vector created by the wind pushing at right angles to the keel? (The keel would be in line with your vector labeled "Boat speed"). If so this might be useful to someone trying to understand the vector diagrams. Also, it seems to me the line labeled cos(beta) is the magic 'extra vector' that allows the boat speed to exceed the wind speed. I am just pointing out some ideas that I see that are important for me to understand how the vectors translate to real world and vice versa. Nice drawings, BTW! —Preceding unsigned comment added by 75.70.3.228 (talk) 00:23, 14 June 2010 (UTC)


 * No, the line labelled "sin(beta)" is not a vector at all. It is merely the length of that segment of the graph.  I put it there so that people can understand how the formula is derived.  Similarly, "cos(beta)" is not an extra vector.  It is simply the length of that segment of the graph.  Again, it is there in order to explain how the formula is derived.  You need to add "cos(beta)" to the segment "x" in order to find the boat speed.--Gautier lebon (talk) 09:28, 14 June 2010 (UTC)

PB's arguments
As far as I can tell, Paul Beardsell presents the following arguments:--Gautier lebon (talk) 08:19, 9 June 2010 (UTC)

1) VMG > windspeed violates the law of conservation of energy. No source is provided to support that statement.
 * No CREDIBLE source is provided to support the alternative view either.--QuietJohn (talk) 07:04, 14 June 2010 (UTC)


 * This is not correct. Bethwaite is a very credible source, as is the observered performance of USA 17, not to mention any iceboat.--Gautier lebon (talk) 09:17, 14 June 2010 (UTC)

2) VMG cannot exceed windspeed because, if it did, there would be no force on the sails. This argument is based on the fallacy that the sails are sensitive to the true wind, whereas in fact they are sensitive to the apparent wind.  The deleted material included numerous references to textbooks that explain this.
 * What you are saying is that it is the APPARENT wind - created the movement of the vehicle itself which allows it to go faster. So the energy of the vehicle moving provides the energy to make the vehicle move faster.... Hmmmmmm? QuietJohn (talk) 07:04, 14 June 2010 (UTC)
 * No, you are confusing velocities with energy. The apparent wind is the velocity difference between the sail and the airmass. The apparent wind determines the force on the sail. The energy on the other hand, always comes from reducing the true wind.Eyytee (talk) 08:43, 14 June 2010 (UTC)
 * Please provide a quote - along with citation (FROM A CREDIBLE TEXTBOOK) to support your claim that VMG downwind CAN exceed windspeed --QuietJohn (talk) 07:04, 14 June 2010 (UTC)


 * It is already there, in the main article: Bethwaite, iceboat data, and USA 17 data.--Gautier lebon (talk) 09:17, 14 June 2010 (UTC)

3) Because of some combination of the above, it cannot be true that USA 17 sailed from the upwind mark to the downwind mark at a speed of 19 knots over the ground in 5-10 knots of wind. Never mind the published accounts, which also state that wind shifts were relatively minor (less that 20 degrees).--Gautier lebon (talk) 08:19, 9 June 2010 (UTC)
 * Again, provide your claimed "published account". Nineteen knots OVERGROUND isn't the same as 19 knots DDW -unless the boat course was DDW. --QuietJohn (talk) 07:04, 14 June 2010 (UTC)


 * But that is the point: the course WAS essentially dead downwind. The first regatta was a banana: up to the mark, back down again.  The data in question are from the first regatta.--Gautier lebon (talk) 09:17, 14 June 2010 (UTC)

4) Because of some combination of (1) and (2) above, the polar charts and other diagrams found in Bentwaithe's book are wrong. That is, the word of one person, unsupported by any citations, should prevail over a book by a well-known expert, published by a reliable publishing house.

Is something wrong here?--Gautier lebon (talk) 08:19, 9 June 2010 (UTC)

Retracting my position: sailing faster *is* possible
I want to apologize for not catching on more quickly here and in the Sailing discussion. This article in Science Daily finally explained this in a way that made intuitive sense to me:.
 * This is what the Science Daily article says..."As the boat speed approaches the wind speed, the relative wind drops towards zero and so there is no force on the sail. So you can't go faster than the wind.".


 * That is a misleading quotation. The full quotation from Science Daily is:--Gautier lebon (talk) 11:06, 14 June 2010 (UTC)


 * Note the key point: you travel at an angle in order to go faster than the wind. Up to two times faster, according to the article.  Which can result in downwind VMG greater than wind speed, as can be seen from elementary trignometry and the polar charts published by Bethwaite and the data from iceboats and USA 17.--Gautier lebon (talk) 11:06, 14 June 2010 (UTC)

Another thing that helped, after reading this article was to think of a spacecraft in space, in two situations. In one situation, particles are shot, all at the same speed, from a fixed location at an object that is floating freely: the object accelerates. At the point the object's speed reaches the speed of the shot particles, the particles can no longer catch the object: the object and the particles are moving at the same speed. In the other situation particles are again shot at an object in space, from a fixed direction, but NOT from a fixed position. All in the same direction -- across miles of space. ALSO, the object is riding on a fixed, straight rail. The particles are shot at 90 degrees to the object -- and at a "sail" that is faced 80 degrees away from path the particles, i.e, almost in line with the direction of travel. Each particle hitting the sail increases the speed of the object -- that is, up until the point where none of the particles can catch the object. That object speed will be MUCH faster than the speed the individual particles are traveling.

Both situations are analogous to a sailing boat. The "particles" are wind, in both situations. In the second situation, the role played by the "fixed straight rail" is similar to the role played by a the boat's keel. Duh. It seems obvious, now. Lol. Regards to all, Alpha Ralpha Boulevard (talk) 19:43, 9 February 2010 (UTC)


 * ...all except for your penultimate sentence in the main para: the particles will always be able to reach the spacecraft as it is on a fixed rail parallel to the one the gun's on. The limit comes from your choice of an 80-degree 'sail'. "Each particle hitting the sail increases the speed of the object -- that is, up until the point where the particles begin to pass down both sides of the 'sail' without hitting it, or are as likely to hit the back or the front of the sail." Nice one. Well done. --Nigelj (talk) 21:07, 9 February 2010 (UTC)

Folks: thank you for your kind comments, but absolutely no apologies are required. As mentioned previously, I too was intially convinced that this was not possible, and it took me a couple of months of research and carefuly thinking to (1) document that is not only possible but commonplace and (2) figure out how it works. And I greatly benefitted from your skeptical comments because they helped me to figure out how to explain the situation more clearly.--Gautier lebon (talk) 13:31, 10 February 2010 (UTC)

Fallacious text cut from article
I have cut the following text from the article and expect to cut more:


 * Note that, if a boat can accelerate until it is sailing at 45 degrees off the apparent wind when sailing 135 degrees off the true wind, then its speed will be 1.41 times the speed of the wind. Thus its velocity made good downwind will be equal to the velocity of the wind.  If it can accelerate until it is sailing closer than 45 degrees to the true wind, then its velocity made good downwind will be greater than the velocity of the wind: see the more detailed discussion in the section Speed made good below.

No! Never, ever is it possible for the hull speed multiplied by the cosine of the apparent angle to the wind to exceed the actual wind speed. No citation is given, and if one is, it would still be wrong! You cannot choose the speed and the angle independantly! They are not independant variables.

It is of course advantageous not to steer directly downwind when trying to reach a point directly downwind. But that is because sails never work well directly downwind. Steering on a broad reach is better than attempting a direct course but still you will NOT beat a free floating balloon.

Paul Beardsell (talk) 16:41, 6 June 2010 (UTC)


 * Actually, there were several citations, but apparently you did not read them, in particular the citations to ice boats and sand yachts. Please read citations before asserting that material is nonsense.--Gautier lebon (talk) 08:43, 7 June 2010 (UTC)


 * I DID read what I could. Some refs are to offline books I do not have.  But I did not want to read them as I understand physical mechanics and I know no mecano-set sailing machine is going to disprove conservation of energy.  BUT NAD THIS IS THE POINT THE REFS DO NOT SAY WHAT YOU WANT THEM TO SAY.  They do talk about 5*windspeed but not about VMG>windspeed.  Except for the hoaxters' site.  Paul Beardsell (talk) 09:14, 7 June 2010 (UTC)


 * It is not about conservation of energy, because the energy contained in the wind is very large. It is about how much of that energy you can harvest in order to overcome resistance from the surface and the induced headwind.  That is explained in the cited sources, please read them again, more carefully.  You assert that  is a hoax site.  But nobody else asserts that.  What is your citation to support your assertion, other than your conviction that such a thing is not possible?--Gautier lebon (talk) 09:21, 7 June 2010 (UTC)


 * The onus is not on me. You want something in the encyclopedia, YOU must find the WP:VSs.  Paul Beardsell (talk) 09:52, 7 June 2010 (UTC)


 * That is not correct. I and others contributed material based on citations.  You challenge the reliability of the citations, which include a book published by a reputable publisher and written by a well-known sailor.  So it is up to you to provide citations that indicated that the original citations were not in fact reliable.--Gautier lebon (talk) 12:19, 7 June 2010 (UTC)


 * I deny your citations supported the text you provided. Alternatively, the citations were to thought experiments here, or they were to the web site of the supposed heroes themselves. None of that meets WP:V Paul Beardsell (talk) 12:08, 8 June 2010 (UTC)


 * As you can see from the discussion below, you are the only person who takes that view. Everybody else agrees that the material was supported by reliable citations.--Gautier lebon (talk) 11:35, 11 June 2010 (UTC)

Nope - I'm with Paul. You can change that by making the statements you wish to make, then providing the citation to support them, preferably as a web page and line numbers. Perhaps even quoting the statements in the web pages so we can find them easily. --QuietJohn (talk) 09:58, 14 June 2010 (UTC)


 * I'm sorry, but the citations are already there. If you carefully read the cited material on the web, you will see that it supports the statements in the article.  For example, please read the whole Science Daily article, not just selected bits.  I have cited Bethwaite.  For copyright reasons, I cannot reproduce in the article his diagrams.  But the diagrams in the article are based on what can be found in most textbooks on sailing.--Gautier lebon (talk) 11:09, 14 June 2010 (UTC)

Reversions
Practically every change I have made to the article has been reverted. I justified every one of the changes here on the Talk page. The reversion is unreasoned. So I have unreverted. Note: Nothing can be in the WP unless supportable by WP:VS. WP policy must be obeyed, like it or not. It is not for us to engage in WP:SYN or WP:OR. Read these policies, please, and ensure you comply with them before re-adding deleted material to the page. Thanks. Paul Beardsell (talk) 10:12, 7 June 2010 (UTC)


 * This is not correct. Your edits were not supported by citations. The article now includes unsupported assertions and original research.  It cannot be allowed to stand as it is. In my opinion, it is your edits that violate WP policy, and that is why I reverted them.  In turn, I would ask you to adhere to WP policy, which is to discuss disputes on the discussion page and not engage in editing wars.  Clearly we need input from other editors.--Gautier lebon (talk) 12:02, 7 June 2010 (UTC)


 * You do need to realise that I do not have to show something is false to remove it from WP. I just have to show it is not properly supported by WP:VS.  The onus on citations etc is on the person adding material.  Paul Beardsell (talk) 12:18, 8 June 2010 (UTC)


 * Please feel free to remove any material which is not supported by WP:VS and which you know to be untrue. Paul Beardsell (talk) 12:16, 8 June 2010 (UTC)


 * Paul, seriously. You're wrong.  You're hilariously wrong.  I've waved this past any number of physicists, engineers, and sailors.  Every time, they say "oh, of course that won't work", and then they do the math to "prove" it, and they say "oh, wait.  I guess it does work.  Neat!"  It's a brain-teaser.  It is counter-*intuitive*.  But intuition isn't science...  That ships can beat the wind downwind is something we have known for literally *centuries*.  It's surprising, sure, but it turns out not to be impossible or anything.  Please stop massively editing an article in a field you apparently know nothing about and are unwilling to learn.  If you really want to have this discussion, go to a *discussion forum*, talk about it, exchange arguments, and come back here once you've either persuaded people or been persuaded. Wikiseebs (talk) 18:35, 10 June 2010 (UTC)

Then get one of your "boffins" to provide a plausible analysis and put it on this page. I'm fascinated but utterly skeptical. Here I am,living on a sailboat, dying to know how to go faster! Come-on - Tell me! Tell me!


 * None of this applies to a conventional sailboat, because its speed is limited by its hull. What we are discussing applies to iceboats, sandyachts, some high-performance catamarans, and some high-performance planing boats such as the 18-foot Skiff.  Bethwaite explains in great details how to go faster: that is what his book is about.  It is readily available, being still in print.  Basically, you need to reduce dramatically the friction on the surface, and you need a rig that will allow you to point very high.  Take a look at USA 17 or Alinghi 5 under sail on the downwind leg of the first regatta and you will see the point: those boats were designed to sail on one float only and they have rigs optimized to sail very close to the apparent wind.  They were designed for optimum VMG up and downwind, whereas most boats have a wider performance range.  The article explains the physics behind the performance.  Bethwaite explains the technologies.--Gautier lebon (talk) 11:15, 14 June 2010 (UTC)

Article directions
1) Paul Beardsell I spent years at a research center specializing in aerodynamics, and I made the same points to Gautier lebon that you did. I discovered on more careful examination that I was wrong, and he was right. There's no violation of conservation of energy involved. You're drawing a false analogy to an object floating free in space, where it cannot exceed the velocity of "wind" impelling it. A boat is not floating freely, it has a keel. I've explained this elsewhere, so I won't repeat.


 * Then how about a link to the explanation? The web is fuullof hoaxers saying "i've explained it" or "I've seen it with my own eyes", but noe REAL corroboration.--QuietJohn (talk) 10:06, 14 June 2010 (UTC)

2) Although WP:V is a Wikipedia core value, the fascination with ruthless application of WP:V to every date, name, and fact is the hobgoblin of little minds. The key phrase there is "This policy requires that anything challenged or likely to be challenged", and this is taken by hobgoblins to mean EVERYTHING. If it meant everything, then it would say everything. The fact you have a disagreement does not necessarily mean that Gautier lebon has to justify himself.

3) On the other hand Gautier lebon, Paul Beardsell has a certain point about WP:SYN. Another pernicious behavior in Wikipedia is believing that because something has been printed, it is encyclopedic. This runs into problems in academic circles, for example, where there are 100s of papers on a subject, and some Wiki editor decides to pick-and-choose which are the most important. In practice these often end up being recent ones published on the Internet. What they should be is the pivotal articles defining the subject that are well-agreed upon as authoritative by that professional community. The selection of those articles should come, preferably, from ANOTHER WP:V source. I.e., the reference source should be the one picking the most important references, not the Wiki editor. This is rarely done — unfortunately the level of scholarship of the typical Wiki editor often does not tend to a wide, professional level of competence in a field. Hence "one off" references tend to be accepted.

I would call out the cited report of the work the experiment-in-progress by San Jose State University as an example of what should not be included. The experiment could fail to prove the hypothesis. It is not necessarily a significant, peer-reviewed experiment. It is crystal ball WP:CRYSTAL.

4) Paul Bearsell is also correct that these paragraphs, for example, does not belong in Wikipedia:


 * "At first, it would seem impossible to sail dead downwind faster than the wind: a wind-driven machine cannot progress dead downwind faster than the wind using only sails. This is because the apparent wind will be zero if the speed of the boat equals the speed of the wind, so the boat cannot possibly go any faster than that. However, in theory, it can sail dead downwind faster than the wind using only energy obtained from the wind while moving (that is, it does not need to stock energy while in the port). Some sort of mechanical device can be used to transfer energy from the surface on which the machine is moving in order to increase the speed of the machine."

Wikipedia is WP:NOT a textbook (Section 2.7). And another Wikipedia article is not a valid reference (let alone a talk page discussion!) Phrases such as "At first, it would seem" and "However, in theory" and "some sort of mechanical device" are signals that the article is straying into being a textbook. These are things professors might say in a classroom. They are not the formal language of an encyclopedia. Read a few articles at random in the Encyclopedia Britannica to get an idea where to anchor your language. Regards to both, Alpha Ralpha Boulevard (talk) 10:59, 7 June 2010 (UTC)


 * The comments from Alpha Ralpha are constructive. I have no problems with improving the article, and indeed there has been a great deal of constructive work in the past.  However, I strongly feel that the edits by Paul Bearsell are inappropriate because they are not supported by any citations and contradict material taken from reliable sources.  In my opinion, the article should be reverted to where it was before Paul Beardsell edited it, and we should discuss improvements on this page.  That will allow the article to be improved, as opposed to its current status, which is most unsatisfactory.--Gautier lebon (talk) 12:07, 7 June 2010 (UTC)

It is well-known that boats can sail faster than the wind. There are thousands of examples, and it is well covered in the physics-of-sailing literature. One good example can be found here Physics of Sailing in Physics Today Magazine (note also the notes to that article for other sources). (Here is another source for references on the subject). Recently (the last four years or so) advances in materials technology have allowed boat builders to build very light craft with reduced drag which not only can sail faster than the wind they can achieve VMG faster than the wind calculated dead downwind. This is a fact. Editors who are arguing here that on one hand examples don't prove anything because it is "original research" and on the other hand, vector diagrams and equations are out-of-bounds because "Wikipedia is not a textbook" are making it impossible for this article to exist. The article needs to explain both the physics of wind-powered vehicles, and to provide examples that prove the case. If folks don't think this article is written well enough to prove the point, they should chip in and re-write it and find better references, not use their discomfort as an excuse to excise large chunks of the article and thus "prove" that you can't sail faster than the wind. I don't mind editors adding tags asking for specific cites or clarification, but deleting things that are demonstratively verifiable facts, is wrong. I wonder what Wikipedia would have said about the shape of the Earth in ~1480?


 * Last point first. An encyclopedia may have said the world was flat in 1480. And that would be correct for an encyclopedia. An encyclopedia reflects established science (even if it is wrong), not controversy.  There is no room for controversy here.  When a WP:VS such as SciAm or NS says it works then WP will say it works.  Until then most we can do is present the controversy.  We are not allowed to engage in WP:SYN or WP:OR in the article pages.  I am happy enough to see it here, on the Talk page, but it cannot leak thru to the article until established as fact by an external verifiable source that satisfies WP:V.  Paul Beardsell (talk) 08:25, 8 June 2010 (UTC)


 * No, it would not have been correct for a 1480 encylopedia to have stated that the world is flat, because all educated people, and all sailors, knew that the world was round since at least 400 BC. The 1480 encyclopedia should do exactly what everybody except Paul Beardsell wants to do.  It should have explained that the world is obviously round because if you watch a boat disappers off the horizon it does not get smaller and smaller; on the contrary, first the hull disappears, then the mast slowly sinks out of sight.  I suppose somebody, in 1480, would have tacked on a "citation needed" tag.  Those people would probably tack a "citation needed" tag on the statement "the sun rises in the East". The point here is whether Wikipedia should contain verifiable facts that contradict common folklore.  The answer to that is obviously yes.  Lots of Wikipedia articles contain information that is not known to people that haven't done the research for themselves: that is the very purpose of any encyclopedia, including Wikipedia.--Gautier lebon (talk) 08:44, 8 June 2010 (UTC)


 * How petty! The point is not about whether the world is flat or not and when the consensus switched from one to the other. The point is that an encyclopedia is NOT controversial.  That we all agree, surely?  If something is controversial better it is NOT in the encyclopedia as we must be able to rely on the pedia, that's the goal.  [As an aside, some clever Greeks knew the world was round millenia ago, they just couldn't carry their point. Maybe that's what you downwind fantasists may have to console yourselves with here.]  Paul Beardsell (talk) 09:02, 8 June 2010 (UTC)


 * Indeed, we agree that controversial, unverifiable statements should not be included. For example, the controversial, unverifiable statement "a boat cannot sail downwind faster than a balloon" should not be included.  The material that you deleted was not controversial. It was developed over a period of months by people who actually took the time to study the citations and undertand the issues.  There is only one person who thinks that the material is controverial: Paul Beardsell.  And the only argument put forward is a supposed violation of conservation of energy.  But, as explained below, there is no violation of conservation of energy. So we are in a situation where one person is using his unsupported assertion to block the patient work of many others.  Further, that person even disputed the suitability of material taken from a book published by a reputable publisher and written by a well-known expert.  Surely this is not consistent with Wikipedia policies?--Gautier lebon (talk) 09:16, 8 June 2010 (UTC)


 * Sigh! The text I removed together with supposedly-supporting citations from the expert was removed BECAUSE the citation did not support the assertion. An editor wrote something which I knew was wrong and what was written was supported, supposedly, by a citation. I followed the link, it said nothing of the kind!  I removed the text and the assertion.  And I said what I had done here on the Talk page.  That is WP policy. Paul Beardsell (talk) 12:23, 8 June 2010 (UTC)


 * The above paragraph (according to the Talk history written by Paul.h) summarises the current editing situation very well. The proposal for an article structure with (at least) an evidence and a physics explanation section is excellent. The latter needs good diagrams like the one proposed by Eyytee below. MrBeanBob (talk) 06:29, 8 June 2010 (UTC)


 * Sorry, but the diagrams are illustrative but misleading. They do not show the vectors at their correct lengths or directions.  They are not proper physical vector diagrams.  The numeric quantity e.g. 1.5 on the diagram is not derived but merely guessed at.  It is difficult to draw good diagrams, I grant you.  But those are little more than pretty pictures, sorry again.  Paul Beardsell (talk) 08:38, 8 June 2010 (UTC)