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how a sail works, who can help me explain?
Boy, are you gonna be happy.
"PIM" wrote in message ... I just translated my dutch website about sail theory into English. English is not my first language, so if someone can help me to make it easier to read and help with some nautical words, that would make me happy. |
how a sail works, who can help me explain?
On Tue, 8 Jul 2003 00:32:51 +0200, "PIM" wrote
this crap: I will not include the latest theories of what deck gun is best. Wuss. Ave Imperator Bush! Bush Was Right! Four More Beers! |
how a sail works, who can help me explain?
The leeward side of a sail is the side that is convex as opposed
to the windward side which is the side that is concave. The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Faster flow equals lower pressure. This low pressure combined with the normal or slightly increased pressure on the windward side is what creates lift. "Oz1" wrote in message ... On Mon, 7 Jul 2003 08:15:31 -0400, "Simple Simon" wrote: A very naive explanation of how a sail works, indeed! Why igore what happens on the leeward side of the sail? OK Cappy, you dropped the hint, now tell us what happens on the leeward side of the sail....first you'd better explain which is the leeward side! Oz1...of the 3 twins. I welcome you to crackerbox palace,We've been expecting you. |
how a sail works, who can help me explain?
"Simple Simon" wrote in message
The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Shouldn't that be "chord"? -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
Yea man!
"Wally" wrote in message ... "Simple Simon" wrote in message The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Shouldn't that be "chord"? -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
I think you should do a little research into Bernouilli and Venturi.
"PIM" wrote in message ... "Simple Simon" wrote The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Faster flow equals lower pressure. This low pressure combined with the normal or slightly increased pressure on the windward side is what creates lift. Dear Simon, I am not neglecting what happens on the leeward of the sail, the leeward of the sail is also deflecting air and thereby creating lift. as I am explaining in www.sailtheory.com/sail.html According the "longer path theory" you use it would not matter how much you pull your sail in, since there is always the same difference in pathlength between windward and leeward. Please read www.sailtheory.com/wrongtheory.html for more examples why it is wrong. The "longer path theory" is not easy to use and is wrong. It is the reason I started my site. Clearly I am not clear enough at this point :) Many agree with me that the longer path theory is wrong: jeff raskin: http://tinylink.com/?RD9ntJyTuz university frankfurt (under 2.2) http://www.informatik.uni-frankfurt..../MIS/mis6.html University of washinton: http://www.aa.washington.edu/faculty/eberhardt/lift.htm Bill beaty: http://www.amasci.com/miscon/miscon4.html#wing And so do the most aerodynamicists as far as I know. I tried to adjust above theories from a wing into a sail. Best Regards Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
I hate to be the one to tell you this, but PIM is correct. Lift is to air as buoyancy is to water.
"Simple Simon" wrote in message ... I think you should do a little research into Bernouilli and Venturi. "PIM" wrote in message ... "Simple Simon" wrote The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Faster flow equals lower pressure. This low pressure combined with the normal or slightly increased pressure on the windward side is what creates lift. Dear Simon, I am not neglecting what happens on the leeward of the sail, the leeward of the sail is also deflecting air and thereby creating lift. as I am explaining in www.sailtheory.com/sail.html According the "longer path theory" you use it would not matter how much you pull your sail in, since there is always the same difference in pathlength between windward and leeward. Please read www.sailtheory.com/wrongtheory.html for more examples why it is wrong. The "longer path theory" is not easy to use and is wrong. It is the reason I started my site. Clearly I am not clear enough at this point :) Many agree with me that the longer path theory is wrong: jeff raskin: http://tinylink.com/?RD9ntJyTuz university frankfurt (under 2.2) http://www.informatik.uni-frankfurt..../MIS/mis6.html University of washinton: http://www.aa.washington.edu/faculty/eberhardt/lift.htm Bill beaty: http://www.amasci.com/miscon/miscon4.html#wing And so do the most aerodynamicists as far as I know. I tried to adjust above theories from a wing into a sail. Best Regards Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote in message
The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Shouldn't that be "chord"? Yea man! The chord is a straight line, not the curved part that the air moves faster over. -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
"Simple Simon" wrote: I find your sources leave somewhat to be desired. Most can't even spell Bernouilli. Some experts!!! You are right about that, many people have problems spelling "bernuli" ;-) Does a wrong spelling makes their theory wrong? I hope not, because my spelling is really worse. :-) It are not my real sources of course, just what I could find online, and that made any sense to me. (although Jeff raskin inspired me to look up the Coanda effect) I think you can also find several links supporting "the longer path theory" Best Regards, Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. The air does not need to speed up to cover the extra length. When you take a longer way to go home home, you will just come home later! same goes for water in a garden hose. The length of the garden hose does not influence the speed through it. Diameter and water flow is of importance. (ok, a really long hose will have so much resistance that the flow will drop) Best Regards, Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote in message
Negative a chord is a straight line joining two points on a curve. This contradicts what you said here... The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
I don't hate to say it but you and PIM are BOTH incorrect.
You both have only a laymans idea of how a sail works. Fact: Venturi effect is proven and accepted Fact: Venturi effect causes lower pressure in the area of the venturi. Fact: Lower pressure is cause by the lower density of the gas molecules in the area. Fact: An object with low pressure on one side and higher pressure on the other side if free to move will move in the direction of the low pressure. THAT is how a sail works. All that other crap is extraneous to the situation at hand aboard a sailboat. There is no high-horsepower motor available to make the sail act as a plane like PIM suggests. All the force is generated by a difference in pressure between the leeward and windward sides of the sail which force acts against the foil in the water and the planeform of the hull to produce forward motion. "jlrogers" wrote in message .com... I hate to be the one to tell you this, but PIM is correct. Lift is to air as buoyancy is to water. "Simple Simon" wrote in message ... I think you should do a little research into Bernouilli and Venturi. "PIM" wrote in message ... "Simple Simon" wrote The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Faster flow equals lower pressure. This low pressure combined with the normal or slightly increased pressure on the windward side is what creates lift. Dear Simon, I am not neglecting what happens on the leeward of the sail, the leeward of the sail is also deflecting air and thereby creating lift. as I am explaining in www.sailtheory.com/sail.html According the "longer path theory" you use it would not matter how much you pull your sail in, since there is always the same difference in pathlength between windward and leeward. Please read www.sailtheory.com/wrongtheory.html for more examples why it is wrong. The "longer path theory" is not easy to use and is wrong. It is the reason I started my site. Clearly I am not clear enough at this point :) Many agree with me that the longer path theory is wrong: jeff raskin: http://tinylink.com/?RD9ntJyTuz university frankfurt (under 2.2) http://www.informatik.uni-frankfurt..../MIS/mis6.html University of washinton: http://www.aa.washington.edu/faculty/eberhardt/lift.htm Bill beaty: http://www.amasci.com/miscon/miscon4.html#wing And so do the most aerodynamicists as far as I know. I tried to adjust above theories from a wing into a sail. Best Regards Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
It does depend on the length difference as stated in the principles
of the venturi effect. The speed of the air is increased when it is forced through a smaller area. The sail acts like one side of a venturi in that the air has a smaller area to go through because of the extra length. The air above that air on the surface of the foil acts like a venturi also to a small degree. The net effect is the air moves faster, the molecules become spaced farther apart and the pressure is decreased. This decreased pressure is a greater factor causing lift than the air pushing up on the windward side of the sail. You might know a lot but you need to learn more when it comes to the practical application of single-surface foils used on sailboats. "PIM" wrote in message ... "Simple Simon" wrote: I think you should do a little research into Bernouilli and Venturi. I did, see www.sailtheory.com/bernoulli.html I am not denying that air goes faster on the leeward, But it is not depending on the length difference (leeward to windward) I used to be a Naval Architect/Yacht designer. Now I am a designer of exhaust systems, for what you need a lot of aerodynamics. So I know of Bernoulli. That I do not use formulas is to make it easy for people who did not study maths muchs Best Regards -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
Ahah! Now, you've finally gotten to the crux of the matter.
You say diameter is the important thing. You are right because when you put a venturi into a hose you get a suction effect at the ventur. The suction proves lower pressure exists in the area of the venturi. In the case of a single surface foil the lower pressure IS caused by the increased length of the surface which has the effect of making a smaller pipe for the air to pass through. "PIM" wrote in message ... "Simple Simon" wrote This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. The air does not need to speed up to cover the extra length. When you take a longer way to go home home, you will just come home later! same goes for water in a garden hose. The length of the garden hose does not influence the speed through it. Diameter and water flow is of importance. (ok, a really long hose will have so much resistance that the flow will drop) Best Regards, Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote in message
It's only a contradiction if one chord from leading edge to trailing edge is envisioned. That is what you envisioned but your vision is apparently limited. The chord I referred to is a combination of many small straight lines (chords) that describe the curve in question. What a feeble wriggle. -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
Hey PUTZ! A misspelled word because of ignorance is
on thing and a misspelled word because of failing to touch a key hard enough is another. By the way, your use of vis-a-vis is incorrect as well as the presentation of it. It should appear as vis-à-vis. "Wally" wrote in message ... Vis-a-vis the use of "cord" instead of "chord"? -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
It's called angle of attack. Increase angle of attach to too
great a degree and the telltales will start telling their tales in in more of a radiating manner. "Oz1" wrote in message ... On Mon, 7 Jul 2003 12:37:55 -0400, "Simple Simon" wrote: The leeward side of a sail is the side that is convex as opposed to the windward side which is the side that is concave. The convex side of the sail or the leeward side directs the air over a longer path. This longer path for the air lowers the pressure because said air must move faster to cover the increased cord. Faster flow equals lower pressure. This low pressure combined with the normal or slightly increased pressure on the windward side is what creates lift. Hmmm can you then eplain why telltales on the concave side of the sail continue to flow? One would have to assume that the air to cover a shorter path would be required to travel in a straight line rather than remain attached to the curve. Oz1...of the 3 twins. I welcome you to crackerbox palace,We've been expecting you. |
how a sail works, who can help me explain?
"Simple Simon" wrote in message news:wN-
Hey PUTZ! Neal! Step *away* from the mirror... A misspelled word because of ignorance is on thing and a misspelled word because of failing to touch a key hard enough is another. And not checking the spelling before posting is the sort of sloppiness you abhor, isn't it? -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
I just translated my dutch website about sail theory into English.
English is not my first language, so if someone can help me to make it easier to read and help with some nautical words, that would make me happy. www.sailtheory.com If some theory Guru out here could help with the content, He (or She) is also welcome. I will not include the latest theories of what deck gun is best. best regards, Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
You are making a mistake: why the air speeds up at leeward.
It has nothing to do with the length difference. If you do not want to leave your good old theory, please consider the one I suggest as an extra. my theory : "the sail deflects the air (on the windward side as well as on the leeward side)" It is very satisfying, it explains a lot. Any way, all theories are a simplification of the reality. more theories to describe the same are possible. The best theory is the one that is the simplest and explains the most. It does not mean all other theories are rubbish! By the way, how do you explain that a flatter sail sails better "pointing" close hauled as a deep(=curved) sail? The more curve the more force according your theory, so what is the use of flattening the sail? (my answer: www.sailtheory.com/sail.html#ch) In reply of your previous post: "Simple Simon" wrote in message Fact: Venturi effect is proven and accepted Venturi effect is in a pipe, in a venturi, There it is indeed proven and accepted. A sail is no venturi. Fact: Venturi effect causes lower pressure in the area of the venturi. yes. Fact: Lower pressure is cause by the lower density of the gas molecules in the area. density difference is not of importance. A keel works just as a sail prducing sideways lift, but density of water stays the same. Fact: An object with low pressure on one side and higher pressure on the other side if free to move will move in the direction of the low pressure. Yes. THAT is how a sail works. There is no venturi. There is a sail. That is the error. All that other crap is extraneous to the situation at hand aboard a sailboat. oh. There is no high-horsepower motor available to make the sail act as a plane like PIM suggests. I do not want to suggest a motor. Sorry if I did. (with "power" I mean energy/time, or force x speed, so not a motor, on my site you can read "force" instead of "power" in most places. It is a small translation error. "power" is in Dutch different from "motorpower" thanks for the hint. This helps improving my site ) All the force is generated by a difference in pressure between the leeward and windward sides of the sail yes, and these pressures are created by changing the direction of the wind locally. which force acts against the foil in the water and the planeform of the hull to produce forward motion. yes. Best regards, Pim www.sailtheory.com -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote It does depend on the length difference as stated in the principles of the venturi effect. The speed of the air is increased when it is forced through a smaller area. I agree. The sail acts like one side of a venturi in that the air has a smaller area to go through because of the extra length. No, there is no real smaller area. The air above that air on the surface of the foil acts like a venturi also to a small degree. !!The distance of the leeward and windward part of the sail is the same!! only when you have some distance from the sail you have some length difference because of taking the "inner turn" ! This means the further away from the sail the bigger the lenght difference so the more the speed difference? I do not think so. The net effect is the air moves faster, the molecules become spaced farther apart and the pressure is decreased. the molecules being spaced further apart are no issue. A wing, sail, or keel can also produce lift under water, and water can not be compressed. This decreased pressure is a greater factor causing lift than the air pushing up on the windward side of the sail. Why? You might know a lot but you need to learn more when it comes to the practical application of single-surface foils used on sailboats. Practical application of sails: I am always learning to become better in sailing. Theoretical: I rule :-) Best regards, Pim -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
"Simple Simon" wrote in message
And not checking the spelling before posting is the sort of sloppiness you abhor, isn't it? Never once did I claim to abhor misspelling. I didn't say you had. It was an example of sloppiness, and I believe I'm right in saying that sloppiness is something that you can't abide. The key phrase was "... is the sort of sloppiness ...". I simply stated that in a published work done at the college level I don't recall you saying "in a published work done at the college level". ... one would tend to doubt the credibility and accuracy of an author who misspells the very topic upon which he expounds. I think that doubting the credibility and accuracy of an author should be based on the truth or otherwise of his premises, and the logical validity of his arguments. And, I did check the spelling with the spell checker but it just so happens that both chord and cord are words correctly spelled. What on earth are you using a spell checker for?? Those things are rubbish! As you ably demonstrated but a few posts ago! What's your excuse for vis-a-vis? I don't speak French, my keyboard doesn't have squggly characters readily to hand, and I don't particularly give a ****. -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
"Simple Simon" wrote in message ... It does depend on the length difference as stated in the principles of the venturi effect. The speed of the air is increased when it is forced through a smaller area. The sail acts like one side of a venturi in that the air has a smaller area to go through because of the extra length. The air above that air on the surface of the foil acts like a venturi also to a small degree. The net effect is the air moves faster, the molecules become spaced farther apart and the pressure is decreased. This decreased pressure is a greater factor causing lift than the air pushing up on the windward side of the sail. You might know a lot but you need to learn more when it comes to the practical application of single-surface foils used on sailboats. If I didn't already know the answer, I'd be tempted to measure both sides of my mainsail - to see if you were right. Fortunately, I am not stupid enough to think that there is a significant difference between the lengths of the windward and leeward surfaces. Where do you get this rubbish from? Are you reading a "definitive" book on the subject? Regards Donal -- |
how a sail works, who can help me explain?
"Wally" wrote in message ... "Simple Simon" wrote in message I think an incorrect spelling of an important name serves to notify the reader that the writer is not very careful or observant. Both are attributes that cause doubt as to the veracity of the author's work. Vis-a-vis the use of "cord" instead of "chord"? Correction - You should have said - "cord" instead of "an infinite series of chords". Regards Donal -- |
how a sail works, who can help me explain?
"Wally" wrote in message news:tbnOa.4848
But the air on each side behaves differently, does it not? On the leeward side, it's passing over a convex shape, on the windward, is it getting fouled inside a concave shape? If so, isn't there a case for saying that the air within the convex Brain slip - should be "... air within the concave ..." -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
Your theory is just not complete. And, to deny an object shaped like a venturi does not act like a venturi is not logical. Just because one generally thinks of a venturi as a tube like in a carburetor it does not mean that a venturi can only be a tube. Air passing over the restriction does not care if it is circular of flattened out. "PIM" wrote in message ... A single surface sail has the same length on leeward as on the windward side. so there IS NO increased length of the surface. I am not denying a Venturi, I am denying that a sail acts as a venturi. Anyway, what is wrong with my theory ? it offers a good explanation of what is happening. Best Regards, Pim www.sailtheory.com "Simple Simon" wrote: Ahah! Now, you've finally gotten to the crux of the matter. You say diameter is the important thing. You are right because when you put a venturi into a hose you get a suction effect at the ventur. The suction proves lower pressure exists in the area of the venturi. In the case of a single surface foil the lower pressure IS caused by the increased length of the surface which has the effect of making a smaller pipe for the air to pass through. -- Posted by news://news.nb.nu |
how a sail works, who can help me explain?
Some things may remain unsaid especially for those too lazy to read the material in question. One cannot spend all one's time complicating a discussion by including everything some reader may have missed. If you had visited the links that were being discussed you would have known. Had you just examimed the links alone without visiting them you would have seen that a couple of them were colleges. "Wally" wrote in message ... I don't recall you saying "in a published work done at the college level". |
how a sail works, who can help me explain?
"Simple Simon" wrote in message news:ie-
Some things may remain unsaid especially for those too lazy to read the material in question. One cannot spend all one's time complicating a discussion by including everything some reader may have missed. If you had visited the links that were being discussed you would have known. Had you just examimed the links alone without visiting them you would have seen that a couple of them were colleges. Gosh. So they were... -- Wally I demand rigidly-defined areas of uncertainty! www.art-gallery.myby.co.uk |
how a sail works, who can help me explain?
"PIM" wrote in message ... By the way, how do you explain that a flatter sail sails better "pointing" close hauled as a deep(=curved) sail? The more curve the more force according your theory, so what is the use of flattening the sail? (my answer: www.sailtheory.com/sail.html#ch) You forget an important concept that of drag. A foil is a compromise between lift and drag. NACA did extensive studies on differently shaped foils and it was all about lift vs.drag. One can make a foil with maximum lift but if it also has maximum drag it will not function very well. If a foil is to full in higher winds it creates more drag. a flatter foil creates less lift but proportionately less drag so overall it is more efficient. A sail is no venturi. Yes it is. Take a venturi. Cut it and unroll it so it is spread out. It is still a venturi but just not a cylindrical venturi. Air molecules don't know if they are passing over a curve in a closed cylinder or a curve in a spread out cylinder. View the sail as a spread out cylinder. Fact: Lower pressure is cause by the lower density of the gas molecules in the area. density difference is not of importance. A keel works just as a sail prducing sideways lift, but density of water stays the same. Density is all important because things happen on a molecular level. It is a fact of physics that lower density equals lower pressure. The measure of pressure of a gas tells you its density. Fact: An object with low pressure on one side and higher pressure on the other side if free to move will move in the direction of the low pressure. Yes. THAT is how a sail works. There is no venturi. There is a sail. That is the error. Incorrect as explained above with respect to the opened and spread out cylinder and how molecules of air see no difference. |
how a sail works, who can help me explain?
You're as bad as PIM in forgetting what angle of attach does to the lengths of the sides of single sided foil. Think of the distance the air molecules must move on the leeward side as opposed to the windward side. The nice curves indicating the movement of individual air molecules demonstrate this nicely. Measure them and see for yourself. Print it out and use a divider. You will be surprised. "Donal" wrote in message ... "Simple Simon" wrote in message ... It does depend on the length difference as stated in the principles of the venturi effect. The speed of the air is increased when it is forced through a smaller area. The sail acts like one side of a venturi in that the air has a smaller area to go through because of the extra length. The air above that air on the surface of the foil acts like a venturi also to a small degree. The net effect is the air moves faster, the molecules become spaced farther apart and the pressure is decreased. This decreased pressure is a greater factor causing lift than the air pushing up on the windward side of the sail. You might know a lot but you need to learn more when it comes to the practical application of single-surface foils used on sailboats. If I didn't already know the answer, I'd be tempted to measure both sides of my mainsail - to see if you were right. Fortunately, I am not stupid enough to think that there is a significant difference between the lengths of the windward and leeward surfaces. Where do you get this rubbish from? Are you reading a "definitive" book on the subject? Regards Donal -- |
how a sail works, who can help me explain?
"Simple Simon" wrote in message ... You're as bad as PIM in forgetting what angle of attach does to the lengths of the sides of single sided foil. Think of the distance the air molecules must move on the leeward side as opposed to the windward side. The nice curves indicating the movement of individual air molecules demonstrate this nicely. Measure them and see for yourself. Print it out and use a divider. You will be surprised. Nonsense! There is an absolutely negligible difference in length between the windward and leeward paths. The wind pushes the windward side of the sail. The keel stops the boat from moving sidways, and the pressure is relieved by the forward movement of the boat. Try pushing a knife through butter to see what I mean. If your theory were correct, then a boat would go *faster* upwind. Regards Donal -- "Donal" wrote in message ... "Simple Simon" wrote in message ... It does depend on the length difference as stated in the principles of the venturi effect. The speed of the air is increased when it is forced through a smaller area. The sail acts like one side of a venturi in that the air has a smaller area to go through because of the extra length. The air above that air on the surface of the foil acts like a venturi also to a small degree. The net effect is the air moves faster, the molecules become spaced farther apart and the pressure is decreased. This decreased pressure is a greater factor causing lift than the air pushing up on the windward side of the sail. You might know a lot but you need to learn more when it comes to the practical application of single-surface foils used on sailboats. If I didn't already know the answer, I'd be tempted to measure both sides of my mainsail - to see if you were right. Fortunately, I am not stupid enough to think that there is a significant difference between the lengths of the windward and leeward surfaces. Where do you get this rubbish from? Are you reading a "definitive" book on the subject? Regards Donal -- |
how a sail works, who can help me explain?
How a sail owrks: Big stick...big piece of cloth....wind.....wind pushes boat...what else do you need to know/
-- katysails s/v Chanteuse Kirie Elite 32 Ad eundum quo nemo ante iit. http://katysails.tripod.com "Women and cats will do as they please, and men and dogs should relax and get used to the idea." - Robert A. Heinlein |
how a sail works, who can help me explain?
"katysails" wrote ... How a sail owrks: Big stick...big piece of cloth....wind.....wind pushes boat...what else do you need to know? how full the ice box is? Scotty |
how a sail works, who can help me explain?
how full the ice box is?
Right now it's full of kimchee and tofu....gonna get those kids to eat nasty old peanut butter if it kills me.... -- katysails s/v Chanteuse Kirie Elite 32 Ad eundum quo nemo ante iit. http://katysails.tripod.com "Women and cats will do as they please, and men and dogs should relax and get used to the idea." - Robert A. Heinlein |
Neal has sex with his dead father!
Bwahahahahaha!
RB |
how a sail works, who can help me explain?
Neal,
Be very careful with your statement on this discussion. You are about to be swallowed by Newton's first three laws. I can feel the smiling, sneering faces.. They know "Bernoulli' is incomplete about sail action. Newton's 1st,2nd,and 3rd Laws are true and more complete BUT either is Newton's Laws. They don't cover the Cosanda (probably wrong spelling) or the apparent circulation forces. I'm still in a muddle about this since the first time thru it. Our Newtonians are using flight theories, which are based on vertical forces. They use terms like ground effects, updrafts and downdrafts which haven't been truly converted to horizontal. They are probably right but also incomplete. Let it go Neal, my friend, Bernoulli will not stand up to close examination. The Newtonian are dingking around for answers they don't have. Drop it on them! And; "I'LL DRINK TO THAT!" Ole Thom P/S Bernoulli will answer your sailing needs. |
how a sail works, who can help me explain?
A Chord is a combination of musical tones.
A scale is a freckle on a fish So What? |
how a sail works, who can help me explain?
Will move in the direction of the lower pressure
Why in the hell couldn't you see that when we were talking about weather systems? OT |
how a sail works, who can help me explain?
"Wally" wrote in message ... "Donal" wrote in message news:bed29j$spv$1 There is an absolutely negligible difference in length between the windward and leeward paths. I just drew a 3000mm long polyline in a CAD package and bent it into an approximation of a section through filled sail viewed in plan. I then offset a new polyline from this by 1mm, simulating the thickness of the cloth. The lengths of the inner and outer surfaces on my model are... Inner: 3016.6077mm Outer: 3016.9590mm Delta: 0.3513mm (For reference, after manipulation, the chord is 2999.6548mm, and the depth of the 'belly' is 114.2920mm, 715.08mm from the leading edge.) Doesn't seem like that could have much effect. Perhaps the Cappy's sails are 2mm thick?? The wind pushes the windward side of the sail. The keel stops the boat from moving sidways, and the pressure is relieved by the forward movement of the boat. Are you saying that the *only* force moving the boat forward is the push on the windward side of the sail? If so... Ahhhh! What is the difference between "push" and "pull". The sail only notices a "difference". If your theory were correct, then a boat would go *faster* upwind. ...does it go fastest downwind? Yes! I've done 15 kts downwind. (using a spinaker). Me best hourly average (8.2kts) was done on a beam reach......... hmmm! That might not be true. I've done Portsmouth entrance to St. Vaast lock in 9:45 under spinaker. WE must have had a few hours of 8.5 kts in that trip. I suspect that we weren't writing up the log on that one. Otherwise I'd remember it. I'll have a look tonight. Regards Donal -- |
how a sail works, who can help me explain?
That's precisely why I give more credence to Venturi.
I like to keep it simple as my name suggests. Why clutter a good physical reality with extra theories that may or may not be applicable? "Thomas Stewart" wrote in message ... Neal, Be very careful with your statement on this discussion. You are about to be swallowed by Newton's first three laws. I can feel the smiling, sneering faces.. They know "Bernoulli' is incomplete about sail action. Newton's 1st,2nd,and 3rd Laws are true and more complete BUT either is Newton's Laws. They don't cover the Cosanda (probably wrong spelling) or the apparent circulation forces. I'm still in a muddle about this since the first time thru it. Our Newtonians are using flight theories, which are based on vertical forces. They use terms like ground effects, updrafts and downdrafts which haven't been truly converted to horizontal. They are probably right but also incomplete. Let it go Neal, my friend, Bernoulli will not stand up to close examination. The Newtonian are dingking around for answers they don't have. Drop it on them! And; "I'LL DRINK TO THAT!" Ole Thom P/S Bernoulli will answer your sailing needs. |
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