Definition of Sailing?

[Kiteship]

Seems trivial enough. We all "know" what it is, so it should be simple enough to define, right?

I'm having a significantly hard time at it, though. I want a succinct, accurate, exclusive definition of "sailing." I want to to encompass all known forms of sailing (including land and ice sailing--and also theoretical ice-ice and land-land sailing), and exclude forms of wind powered motion which aren't sailing (using a turbine to charge a battery, then using the battery to move the boat; or using potential energy to story transient vagaries of wind, as sea birds do). I want to include Peter Sharp's "powered alternate sailing" (if you aren't familiar with this you should be; it's fascinating), but should probably exclude "solar sailing" (though photons have no mass, they do posses momentum--so sailing using them should be possible. OTOH, "sailing" ought to require two fluids (or other material media), it seems to me and solar sailing only has the one--it uses gravity as a second "working fluid", which clearly isn't kosher. (I think!)

I am also having trouble including such simple "sailing" as a leaf (or a clipper ship) being blown DDW across a pond; if this is not sailing (no second "medium;" the water need not be involved), then what is? (eg; if a leaf blowing across a pond is sailing, then why is a leaf blowing through the air, not?) No, it isn't just about drag; If I use a kite to pull a hovercraft DDW, the friction is trivialized--but I am still clearly "sailing," or at least motorsailing)

"Interface vehicle" is the most succinct I can manage to date, but I don't pretend it is a sufficient definition. (and damn, "most succinct" smacks of redundancy itself!)

What do *you* think?

Cheers,

Dave Culp

[gggGuest]

> or using potential energy to story transient vagaries of wind, as sea birds do).

And so does every flecible sailboat rig - its a key factory in "gust reponse"

> uses gravity as a second "working fluid", which clearly isn't kosher. (I think!)

Its kosher enough in the Racing rules of sailing:-)

I think there's why you're getting in trouble Dave, you're attempting to posit a rigid boundary to a flexible condition... I don't think you can get a rigid definition.

[Kiteship]

But, you don't even offer a flexible definition. ;-)

What *is* sailing?

D

[Crag Cay]

To use the power of the wind alone to move 'a vessel' to a given point decided upon by the skipper.

This eradication of mearly being 'blown along', seperates sailing from trash in the street, leaves on a pond and Westsail 32's.

[Tim B]

Sailing may be defined as the act of going somewhere across water, propelled by the wind and supported, primarily by bouyancy due to displacement of said water.

Tim B.

[Doug Lord]

Maybe: "Non-random movement as a direct result of wind pressure"

[Kiteship]

Sailing is not limited to wind, or water. What about land sailing, ice sailing, and air-to-air sailing? (also what about solid-solid sailing--it *is* possible)

[Doug Lord]

There are no limitations on my definition except the use of wind pressure to create the movement and the fact that it is not random movement.

[Kiteship]

You do not need wind to sail, Doug. You could, for instance, use a river's current on a windless day. You could also use a river current, coupled to a heavy craft running on the river's bottom (like land sailing, but using water, not air). FWIW, the craft doesn't need to be underwater, but could be on the shore, coupled to the river current by a line (this is then kite sailing--still not using wind). It is also possible to "sail" between two solid surfaces, so long as they are moving, relative to each other, and so long as you can couple the two together. You can also "sail" between relative moving bodies of water (as between a current and still water nearby) and also in the air, between different air currents (this time you do use "wind" but you use nothing else!)

C'mon folks, let's think harder! There is some good info about this in recent AYRS publications.

There are no limitations on my definition except the use of wind pressure to create the movement and the fact that it is not random movement.

[Mychael]

Hmm, so would you consider flying a glider that uses thermals to provide lift as a form of sailing.?? When there are no thermals so therfore no positive lift, then you are just gliding.

Mychael

[Kiteship]

Typically, no. A glider uses the vertical lift from thermals. Blowing things vertically with vertical currents isn't "sailing," I think you'd agree. However, the reasons why soaring isn't sailing might be helpful in developing a definition of sailing.

FWIW, this isn't *my* definition of sailing--it's not a quiz. Sailing is sailing. What we're looking for is a definition.

D.

Hmm, so would you consider flying a glider that uses thermals to provide lift as a form of sailing.?? When there are no thermals so therfore no positive lift, then you are just gliding.

Mychael

[yipster]

ok you opened the thread under sailboats
but wonder isnt a powerboat also sailing on water?
a quik look in the dictionairy here:
sail=controlling+fload (thrue)
sailing=to sail+boattrip

[DGreenwood]

Utilizing a decoupled flow at an interface of two fluids or a fluid and a solid, to advance a vehicle through or over one of two said media.

Jeez this is getting ridiculous

[DGreenwood]

"Sailing boats exploit the discontinuity in fluid flow that exists at the air/water interface in order to propel themselves."

Joseph Norwood

High Speed Sailing-Design Factors- A study of high performance multihull yacht design
1979
Adlard Coles-Granada Publishing UK

Not a complete definition under Kiteships required inclusion of land sailors.

[LP]

not original, but. . .

Going nowhere slowly at great expense.

And my addition.

Going there a little faster at excessive expense.

:D :D :D

[DGreenwood]

Or if you wish to include gliding:

The utilization of the interaction of two natural forces for the determinate propulsion of a vehicle.

Don't like the word "natural" but I couldn't think of another. One of the two forces, of course, would be gravity.

Now it's really getting crazy

[DGreenwood]

Getting way too deep into this, one could describe how said vehicle uses a couple between two media to effect propulsion?

OK OK I'll stop!

[yipster]

you mean propulsing the adhesion between the gasses we sail in :D

[Doug Lord]

You do not need wind to sail, Doug.
----------
Says who? Give me a break! Wind is the essence of sailing.... You may be able to contrive other forms of movement similar to sailing but sailing requires wind .

[DGreenwood]

Yipster
English is my second language---I don't have a first!
So once an idea has filtered through the disorganized mess of my brain and then translated by dutchman, we have something really scary...but you know I think I get your drift.

[DGreenwood]

So Doug...what about solar sailing? Space ships do it.

[Doug Lord]

You answered your own question, DG: you didn't say what about sailing you said what about solar sailing....Similar to(perhaps) but not including...

[markdrela]

How about this:
"Extracting propulsive energy from the airmass moving past another medium, such as water, ice, or ground."

This eliminates passively drifting objects like leaves, balloons, or free buoys moving down a river.

You could make the concept more general by allowing the "other medium" to be another airmass with a different velocity. In this case you can "sail" in the shear layer between them using a dirigible equipped with two sails -- one sail is in the airmass above, and another sail (a keel in effect) is in the airmass below. As long as the shear layer is present, such a dirigible could move in almost any direction, outside of the minimum pointing angle limits.

"Sailing" on a horizontal air shear layer can be more easily done with heavier-than-air vehicles if done dynamically. The albatross does this in the shear layer (boundary layer) just above the ocean surface. A much more spectacular example is "Dynamic Soaring" by RC gliders, in the lee side shear layer behind a mountain crest. The current speed record is 301 mph in roughly a 45 mph wind shear layer velocity. Here's some info and a bunch of videos:
http://en.wikipedia.org/wiki/Dynamic_soaring

[ron17571]

Its when a sailboat moves because theres wind.when ur sailboat dosent have any wind and u sit there it isnt sailing,its hell.you get the idea.

[Kiteship]

No, please don't stop. You are making great progress. Yes, there must be a couple between two media. Yes there must be propulsion. Yes, it is a vehicular concept. Keep it coming!

Dave

Getting way too deep into this, one could describe how said vehicle uses a couple between two media to effect propulsion?

OK OK I'll stop!

[DGreenwood]

And as I said before I think it must be determinate propulsion. Not random drifting in a fluid stream.
So...
The determinate or controlled propulsion of a vehicle effected by a couple developed between at least one natural energy source and an interfacing counter influence.

Damn...I am not a trained physiscist and I've run out of words. I'd say without causing me to get a headache that isabout as close as I can get.

I'm geting the impression you already have a source for this deifinition or come up with one yourself.

[Kiteship]

Thanks for coming into the thread, Mark. I feel honored.

I think we're all seeing that, just as with the "definition of 'boat'" thread, it is sometimes a semantics issue, but moreover, it's a matter of stating what sailing *isn't*, then developing a (hopefully simple) definition from what's left.

So, sailing is clearly propulsion. Devices whose primary job is to produce power aren't sailcraft, then (unless they move!)

It's also clear that another friend of mine, Pater Sharp, accurately defines at least of 6 sailing "contexts:" air/water, air/air, water/solid, water/water, solid/air, and solid/solid. Ordinary water "sailing" uses one of these, land/ice sailing another. Mark points out a third (air/air), and I proposed a fourth and fifth in an earlier email (water/water and water/solid), and hinted at the sixth, solid/solid. Only this last fails to appear naturally--unless you consider things like plate techtonics or iceberg/landmass motion (which I suppose *should* be considered, so I retract the "fails to appear naturally" comment). Yeah, I can imagine a "sailcraft" designed to exploit the movement of continental plates in order to move things--like, maybe million-ton "sailboats."

Actually, Peter counts 12 contexts; introducing reference point of view to each of the above; thus he defines a difference between sailing on motionless water with wind and sailing in a current on a windless day. I count these as identical, as they only differ in relative point of view, but there you are.

Question; are there other contexts for sailing? Are Mark's suggestions re: slope soaring or time-shifted sheer boundary flight (the albatross), both of which use potential energy (gravity) to "couple" the differing media sailing? Including--or excluding--things like potential energy would go a long ways towards a common definition; Is gliding sailing? The sport gets its energy entirely from transient vertical movements of air masses, then cleverly translates this energy to horizontal movement (horizontal movement = propulsion, no? Thus horizontal motion--or more generally, motion parallel to the interface between media--is probably a requirement of sailing. Do you agree or disagree?)

Also, should the utilization of vertical movements of the media (more generally, movement perpendicular to the interface) be "allowed" in sailing? Slope soaring certainly requires uplift of wind currents--and also gravity as a "working fluid" even though no net potential energy is gained (or does it? Mark?). Careful, if we allow vertical movement of the media, things like soaring become sailing, as do things like "slope soaring" of wind deflected off waves, which seabirds use extensively. Is this sailing?

I like the concept of momentum exchange between the coupled media as part and parcel of "sailing." Without momentum exchange, there is only drifting, not sailing (does this mean that a leaf, or a clipper ship, moving directly downwind is only "drifting," not "sailing"?) I also like the restriction to movement (generally) in a plane parallel to the interface between media (thus a sailboat must stay on the surface of the sea, in order to remain a sailboat. Amick Flying boats, therefore, aren't sailcraft (search "freepatentsonline" for Amick Flying boat if not familiar with it.)

Then again, though massless, photons do have momentum. Thus "solar sailing" is possible--or is it? Where's the second medium for coupling photon momentum exchange to? Gravity? Hmmm. Gravity is a force, not a moment...

Cheers,

Dave

How about this:
"Extracting propulsive energy from the airmass moving past another medium, such as water, ice, or ground."

This eliminates passively drifting objects like leaves, balloons, or free buoys moving down a river.

You could make the concept more general by allowing the "other medium" to be another airmass with a different velocity. In this case you can "sail" in the shear layer between them using a dirigible equipped with two sails -- one sail is in the airmass above, and another sail (a keel in effect) is in the airmass below. As long as the shear layer is present, such a dirigible could move in almost any direction, outside of the minimum pointing angle limits.

"Sailing" on a horizontal air shear layer can be more easily done with heavier-than-air vehicles if done dynamically. The albatross does this in the shear layer (boundary layer) just above the ocean surface. A much more spectacular example is "Dynamic Soaring" by RC gliders, in the lee side shear layer behind a mountain crest. The current speed record is 301 mph in roughly a 45 mph wind shear layer velocity. Here's some info and a bunch of videos:
http://en.wikipedia.org/wiki/Dynamic_soaring

[Kiteship]

No, I really don't, and I haven't. I've wrestled with this for a long time, though. Definitions are important.

I'm getting the impression you already have a source for this definition or come up with one yourself.

[DGreenwood]

The crazy thing is that solar sailing does actually rely on gravity as well. Much of how it is used is counter intuitive. The crazy thing is that a vehicle can sail and increase speed going directly toward the sun without using power conversion as we normally think of that. Any way in order to have a derterminate effect on the coarse of said vehicle we do need the second effecting force of gravity.
Somebody can correct me if I'm wrong, but ouside the effect of gravity, and if we could still have the effects of photons we would be rudderless and require artificial propulsion of some sort to direct our course.

[Kiteship]

NASA, via NIAC (NASA Institute for Advance Concepts) recently funded an investigation into both horizontal air shear exploitation and also buoyancy-altering LTA/HTA soaring for extra-planetary exploration 2 years ago. Some interesting stuff in their final report here: http://www.niac.usra.edu/studies/study.jsp?id=1010&cpnum=04-01&phase=I&last=Woolsey&first=Craig&middle=&title=A%20Self-Sustaining,%20Boundary-Layer-Adapted%20System%20for%20Terrain%20Exploration%20and%20Environmental%20Sampling&organization=Virginia%20Polytechnic%20Institute%20&%20State%20University&begin_date=2004-10-01%2000:00:00.0&end_date=2005-03-31%2000:00:00.0

Or try this, using SnipURL: http://snipurl.com/13d1p


"Sailing" on a horizontal air shear layer can be more easily done with heavier-than-air vehicles if done dynamically. The albatross does this in the shear layer (boundary layer) just above the ocean surface. A much more spectacular example is "Dynamic Soaring" by RC gliders, in the lee side shear layer behind a mountain crest. The current speed record is 301 mph in roughly a 45 mph wind shear layer velocity. Here's some info and a bunch of videos:
http://en.wikipedia.org/wiki/Dynamic_soaring

[markdrela]

Question; are there other contexts for sailing? Are Mark's suggestions re: slope soaring or time-shifted sheer boundary flight (the albatross), both of which use potential energy (gravity) to "couple" the differing media sailing?
Gravity or potential energy is not required for Dynamic Soaring (DS). An RC glider DS'ing at 300 mph is pulling something like 50g turns, so gravity is only 2% of the overall forces involved.

What is required is sufficient inertia, or more precisely, a sufficiently large L/D or ballistic coefficient. This allows maintaining most of the kinetic energy in between the periodic kicks provided by the shear layer crossings. If most of the kinetic energy were to bleed off between kicks, the DS cycle could not be sustained.

[Doug Lord]

Perhaps starting with the definition of definition= "a statement expressing the essential nature of something". This is going away from describing the essential nature of sailing; it is delving into area's similar to sailing but not sailing-in my humble opinion.
I still like:
"Non-random movement as a direct result of wind pressure"

[rayk]

What about a surface vehicle equiped with a wing that provides propulsive force in the form of lift... from the wind... contrary to ....that can be propelled in any direction... contrary to the...
Sailing must be a human deflecting a moving mass...argggh wind wind dammit!
Its a guy on a boat who can make it go in any direction (usually somewhere safe to anchor with a good pub on the waterfront) just by putting a sail up. No. To simple.
Anyway I there must be a martyr/victim/fool/person rolled into this definition somehow. Or sailing will end up like NASA,where the tecchies moan about wasting money on live meat space exploration. Everyone knows no one is gonna live on Mars. Who wants to live on the moon, it must be easier but theres no point. :confused:
Where was I?

:idea:
Sailing is done on the sea in a boat with a sail. Anyone else using the word without these ingredients is just ripping off the word. And then having the cheek to say sailing needs a clearer definition!:mad:
Whoever invented ice yachts or solar sailing could have extended their genius to inventing a new word I think.
Sailing is an old definition not a broad one. And it doesnt need to get jazzed up and modern. :P

[DGreenwood]

Maybe you should look up the word "essential" Doug

[Doug Lord]

Sure DG:

essential=
1) of ,relating to ,or constituting essence,
2) of the utmost importance: basic,indispensable,
necessary
------
You know- like "wind pressure" and "non-random"- in any realistic, practical, usable definition of sailing....

[DGreenwood]

Wow! Is it just me or does the word essence seem to imply something more than "a dude on a boat on an ocean" explaination?

And I see you are getting mighty commanding with those words "realistic" and "practical" and my particular fave..."usable"

Even if we are over defining it...what is it about the fun of trying that bothers you so much?

[Doug Lord]

I'm not bothered in the least but having to explain this(or something like it) to some kid at Kelly Park on the weekend could be bothersome:
"Now, looky here kid, sailing is utilizing a decoupled flow at an interface of two fluids or a fluid and a solid, to advance a vehicle through or over one of two said media-now get out there and show us what you've learned!"
DG, you said:" Geez, this is getting ridiulous"
and I'm just agreeing with you.....

[yipster]

this is clear cut forexample
Its when a sailboat moves because theres wind.when ur sailboat dosent have any wind and u sit there it isnt sailing,its hell.you get the idea.
but the definition stretches couse you agree a motorboat also sails ya?
can we say a keel does? think so, think we can even say a prop does.
dont realy know if we can say an electron "sails" around hydrogen though

[DGreenwood]

Gravity or potential energy is not required for Dynamic Soaring (DS). An RC glider DS'ing at 300 mph is pulling something like 50g turns, so gravity is only 2% of the overall forces involved.

What is required is sufficient inertia, or more precisely, a sufficiently large L/D or ballistic coefficient. This allows maintaining most of the kinetic energy in between the periodic kicks provided by the shear layer crossings. If most of the kinetic energy were to bleed off between kicks, the DS cycle could not be sustained.

I see your point. But without that potential energy we could not have travel in the direction of the wind source. So we come back to Daves question...is that the defining criteria. how much freedom do you need in your choice of movement before you can call it sailing.
It brings to mind those characters that crossed the Atlantic from New York on a floating pile of rubbish that had a blue tarp sticking out the top. They definitely had drifting confused with sailing.

[DGreenwood]

Doug
You say you are not bothered..but you seem very bothered.

My comments about getting ridiculous are called "having fun"...can you say "fun" ...I'll betcha' can!?

[rayk]

....how much freedom do you need in your choice of movement before you can call it sailing.


A boat would have to make ground against the wind I think. Thats what makes sailing so cool. You can make ground using the very thing thats trying to blow you away.
It is like trying to use gravity to climb up a wall.
:confused:

[Kiteship]

Gravity or potential energy is not required for Dynamic Soaring (DS). An RC glider DS'ing at 300 mph is pulling something like 50g turns, so gravity is only 2% of the overall forces involved.

What is required is sufficient inertia, or more precisely, a sufficiently large L/D or ballistic coefficient. This allows maintaining most of the kinetic energy in between the periodic kicks provided by the shear layer crossings. If most of the kinetic energy were to bleed off between kicks, the DS cycle could not be sustained.

Hmmm, and I presume you can also stipulate that both media move only parallel to each other--that is, parallel to the ground (no thermal lift)? I'd always more or less dismissed slope soaring, believing it relied on thermals/non-parallel interface in order to work. Thanks for the references.

Let's take this a bit farther afield, then and see where it takes us (I'm hijacking my own thread here, but I really want to know what Mark thinks). If all that's required is an energetic momentum differential between the media and sufficient inertia in the vehicle, well then, couldn't we use the interface--the vertical interface--between the jet stream and still air? Has anyone tried this? I can see potential inertia issues (the interface between media may be too large to carry inertia across), but wouldn't this perhaps, allow very fast, heavy devices to "sail" hither and yon? We are already experimenting with kites-flown-from-blimps as air/air sailcraft.

Or, staying with the water/wind interface (I love the old sobriquet, "Ancient Interface"), couldn't one build a "flying fish," capable of diving into water, wings folded, then swooping back into the air, spreading wings, then diving back into water to repeat the Dynamic Soaring cycle? I'm not just supposing here; the US Navy is spending significant money on extremely long range robotic reconnaissance these days. Here's a potentially very efficient "sailing" craft, which could be very, very fast as well.


:idea:
Sailing is done on the sea in a boat with a sail. Anyone else using the word without these ingredients is just ripping off the word. And then having the cheek to say sailing needs a clearer definition!:mad:
Whoever invented ice yachts or solar sailing could have extended their genius to inventing a new word I think.
Sailing is an old definition not a broad one. And it doesnt need to get jazzed up and modern. :P

Thanks for checking in, Mr. Ludd. Problem is, you bring us back to the original issue; what is the definition of sailing? If it's just your old gaff schooner on a New England Fall afternoon, what, pray tell, are those guys doing on the Wisconsin ice? They are using the identical same physics you are using, and having the identical results you are. But your name is already taken, so maybe they're "ice-wind sliding" eh? C'mon, come into the 20th century (we'll work on the 21st later). Point is, a definition both describes--and limits--that thing it defines. Do you really believe ice sailing is not sailing?

Cheers,

Dave

[rayk]

Ludd here.
Ice wind sliding... ice-wind sliding... ice wind-sliding...
Im tempted.
But after checking in the A-K volume of my encyclopedia set, Ice sailing seems a legitimate use and would appear to share something in common with sailing.
But I stand firm on solar sailing! The technology isnt even available yet. Rename it. I have my ways. To discuss this matter in private visit me aboard the good ship Spinning Jenny.

[MalSmith]

In order to provide a broad enough definition of sailing to encompass gliders and solar yachts, yet specific enough to eliminate devices with multiple energy conversions it is probably necessary to break the definition into parts. I would propose a definition something like this:

Sail: A plate like device which derives a force directly from a moving fluid by creating a pressure differential in the moving fluid either side of the device.

Sailing: The operation of a sailing vehicle.

Sailing vehicle: A payload carrying device which obtains directed motion by deriving a motive force from the vector sum of at least two other forces, at least one of which is obtained by using a sail.

Note that by this definition a Hydrofoil is a sail like device specifically designed for use in water, and an Aerofoil is a sail like device specifically designed for use in air.

Mal.

[Kaa]

LOL. A funny thread.

Definitions are important, yes. But definitions don't exist in a vacuum, a good definition is one that serves a specific PURPOSE. For complex subjects it's possible to give several -- nay, several dozens -- definitions which will all be correct in the specific framework where the definition is used. These multiple definitions don't even need to agree with each other as long as it's clear to which context a definition belongs and as long as it's USEFUL in such a context.

Define us a context, a purpose for a definition of "sailing" and the task of formulating said definition will become much, much easier.

Kaa

[Kiteship]

In order to provide a broad enough definition of sailing to encompass gliders and solar yachts, yet specific enough to eliminate devices with multiple energy conversions it is probably necessary to break the definition into parts. I would propose a definition something like this:

Sail: A plate like device which derives a force directly from a moving fluid by creating a pressure differential in the moving fluid either side of the device.

Sailing: The operation of a sailing vehicle.

Sailing vehicle: A payload carrying device which obtains directed motion by deriving a motive force from the vector sum of at least two other forces, at least one of which is obtained by using a sail.

Note that by this definition a Hydrofoil is a sail like device specifically designed for use in water, and an Aerofoil is a sail like device specifically designed for use in air.

Mal.

I agree with Theo Schmidt (on another server) that, once you get into things like gliding, it's a slippery slope, 'cause you've brought energy storage into the equation. Pretty quickly you're refining and burning dinosaurs and calling it "sailing." Still, what if you time-limited the energy storage--the time needed to "sail" would need to include the time needed to store the energy--or to put it another way; all storage systems shall have the same potential at the end of the "sailing" journey as at the beginning? Peter Sharp's PAS (powered alternate sailing) closely skirts this issue as well.

(Have we seen PAS here yet? It's the concept of coupling two "saiilboats" together, for instance via an extension cord, then anchoring one (with a drogue, for purists), letting it extract energy WHICH POWERS THE *OTHER* COMPONENT CRAFT. When the "end of the cord" is reached, the two components swap modes, and the entire "sailcraft" moves forward, in increments. Seems silly maybe, but this offers the ability, for instance, to sail dead upwind faster than wind; downwind *much* faster than wind, and other tricks (the bit which is extracting power has no drag--it's standing still, while the moving bit can be heavily streamlined). The version I outline is only one of many--PAS can include purely mechanical linkage, even rigid linkage; the concept is that it alternates between "extraction" and "consumption" modes to increase efficiency. Usually, the "definition" of PAS includes no energy storage allowed, but it's maybe just as "pure" to allow storage, then require the sum total potential to be the same at the "end" as at the beginning. It's thinking about PAS vehicles that's got me thinking about definitions of sailing.

Interesting that you allow "forces" not "momentum of media," Mal. I assume you're allowing gravity, then? How about magnetic forces? Careful, pretty soon you've got electric motors in your "sailboat." ;-)

Still, this is the best I've seen so far; I like your deterministic approach, Mal.

Dave

LOL. A funny thread.

Definitions are important, yes. But definitions don't exist in a vacuum, a good definition is one that serves a specific PURPOSE. For complex subjects it's possible to give several -- nay, several dozens -- definitions which will all be correct in the specific framework where the definition is used. These multiple definitions don't even need to agree with each other as long as it's clear to which context a definition belongs and as long as it's USEFUL in such a context.

Define us a context, a purpose for a definition of "sailing" and the task of formulating said definition will become much, much easier.

Kaa
I understand your point, but we don't need multiple definitions for things like "lift," "drag," "fly," "asymptote," etc. Why do we need one for "sailing?" (OK, it seems a given to me that we aren't talking about "sail" as in "The cruise ship sailed earlier today") Perhaps I'm presuming here, but the context is moving vehicles via naturally-occurring energy sources; is it necessary--or helpful--to say so?

We all sort of "get it" that sailing requires two media (perhaps more?), coupled together, and that it requires some sort of "gathering" device in each media. Unsaid is that the two media have to have relatively divergent momentums, or we have nothing to gather. We seem to be approaching agreement that it shouldn't involve stored energy, and (I suggest) staying away from coupled "forces" might be a good idea.

[MalSmith]

Dave,

It seems to me that the essential aspect of any sailing vehicle is that it has a "sail" of some kind, which is why I think it is important to try and define what a sail is. I've tried to keep the definition of a sail very broad i.e. to use it as an umbrella term for any kind of device that creates a force by effecting the momentum of a moving fluid. The fluid can be a liquid, a gas or particle stream, in order to encompass the the broadest use of the term. Perhaps it would almost be sufficient to define a sailing vehicle simply as "any vehicle which uses uses a sail to obtain it's motive force".

Nautrally the motive force will react against another force. For a leaf being blown in the wind, the force reacts against the momentum of the leaf itself (while it is accelerating). However, we wouldn't really consider this as sailing, because the direction of motion of the leaf is not controlled. We design a sailing vehicle so that we can arrange the reactive forces in such a way as to be able to control the direction of travel, subject to the limitations of the system. In addition to this, there is usually a system for the fuction of maintaining stability. Perhaps then the essential features of directional control and stability control need to be included in the definition (depending on what you want to use the definition for).

I don't have a problem with including gravity (gliders, solar ships), momentum(gliders, solar ships), magnetism (sail powered magnetic train??), friction (land yachts), bouyancy and of course fluid pressure as some of the possible reactive forces. Note that a "normal" sailing boat uses fluid pressure to control direction and a combination of gravity and bouancy to control stability (pitch and roll).

Mal.

[rayk]

A boat from a hundred years ago is sailing dudes. That is the root.

Define that first and then figure out if the rest of the exotic rubbish is like sailing.

Define *pointy head* :p

[longliner45]

rayk ,,,your just twisted enough to be a sailor.......longliner

[Kaa]

I understand your point, but we don't need multiple definitions for things like "lift," "drag," "fly," "asymptote," etc. Why do we need one for "sailing?" (OK, it seems a given to me that we aren't talking about "sail" as in "The cruise ship sailed earlier today") Perhaps I'm presuming here, but the context is moving vehicles via naturally-occurring energy sources; is it necessary--or helpful--to say so?

We don't need multiple definitions for words like "lift" and "drag" because there is a very clear implied context for them -- that of physics, and specifically aerodynamics. Specify just as a clear context for "sailing" and the definition will be easier to come to.

Generally speaking, there are two reasons for definitions. Reason one is clarity of thinking. When your mind manipulates concepts, having a well-drawn boundaries around these concepts helps a lot. This works in reverse as well -- vague or just muddy definitions lead to muddy thinking and lots of problems.

Reason two is communication. When people communicate, they have to agree on the meaning of symbols they exchange -- defining things is the first step in such an agreement.

We all sort of "get it" that sailing requires two media (perhaps more?), coupled together, and that it requires some sort of "gathering" device in each media. Unsaid is that the two media have to have relatively divergent momentums, or we have nothing to gather. We seem to be approaching agreement that it shouldn't involve stored energy, and (I suggest) staying away from coupled "forces" might be a good idea.

Well, I think you are making this way more complicated than it should be. But it looks to be a fun game, so let's try to make up some definitions.

Here's a simple and basic one:

"Sailing is a method of vehicle propulsion which utilizes sails as the main method of converting wind to vehicle movement".

Note that I said "wind". Movement on the boundaries of liquid and solid medias, etc. etc. should have a different name. If you take, say, a land yacht and put it on the bottom of a river, it should be able to move utilizing the river current as power for its sails (we'll assume suitable river bottom, suitable sails, etc.). I, however, don't consider that to be sailing and don't see much point in trying to stretch the definition of sailing to cover this.

Now we've made some progress, but to a certain degree we just passed the buck -- we now need a definition for the word "sail". That is a more fuzzy area. A possible narrow definition will distinguish between sails and rigid wings and say something like "A sail is a sheet of flexible material that relies on pressure differential on its two sides to provide thrust". Under this definition rigid wing sails aren't really sails -- they are just wings put on their side.

Maybe this is too narrow (although it would make lots of sense to a non-technical audience), so let's include rigid wing sails by discarding the flexibility requirement. That means, however, that we also need to think about excluding windmill-type arrangements. One way of doing this would be to specify that "true" sails must be able provide thrust statically in a local time frame. I am not sure how to phrase it more elegantly, but it means that if you freeze the sail in time it will still provide thrust, while a windmill would not -- it needs to rotate to do something useful.

Here however, we are entering the lands of angels dancing on pin heads. It can be an agreeable form of mental masturbation, but if you want something actually USEFUL to come out of the exercise, we should have already specified a clear purpose and context to a definition a few paragraphs before :-)

Kaa

[Kiteship]

What you offer--and many others as well--is a description of something you observe. I see a creature with wings, moving through the air. I shall call it "bird" and define it as a creature with wings, which moves through the air. These are not definitions, they are descriptions. A definition for "bird" would include its taxonomy, its anatomy, likely a history of its evolution. It might address the aerodynamic capabilities of the creature's wings, bones and musculature; and the fact that it's primary mode of flight is flapping, not fixed wings. Curiously, the actual definition of "bird" does not require flight, as we all know. If I used your method for defining "bird" surely no penguin, or emu would be a "bird."

Dave

[rayk]

Flightless birds

[Kaa]

What you offer--and many others as well--is a description of something you observe. I see a creature with wings, moving through the air. I shall call it "bird" and define it as a creature with wings, which moves through the air. These are not definitions, they are descriptions. A definition for "bird" would include its taxonomy, its anatomy, likely a history of its evolution. It might address the aerodynamic capabilities of the creature's wings, bones and musculature; and the fact that it's primary mode of flight is flapping, not fixed wings. Curiously, the actual definition of "bird" does not require flight, as we all know. If I used your method for defining "bird" surely no penguin, or emu would be a "bird."

Dave

Funny, I would say that "its taxonomy, its anatomy, likely a history of its evolution" belong to an extended description, but certainly not to a definition.

Let's try it from another angle. The function of a definition is to create a boundary -- to separate something from something-else. We want to define what a bird is in order to separate birds from mammals, reptiles, etc.

What are things (concepts) that you want to delineate sailing from?

For example, we want to separate sailing from drifting. A lot of things move because they are pushed by the wind or the current but we won't call it sailing. We want to separate sailing from poweboating even in cases where the boat mounts a wind generator and ultimately uses the wind energy for moving.

Between sailing and what else do you want to draw a clear boundary?

Kaa

[Kiteship]

What are things (concepts) that you want to delineate sailing from?

For example, we want to separate sailing from drifting. A lot of things move because they are pushed by the wind or the current but we won't call it sailing. We want to separate sailing from poweboating even in cases where the boat mounts a wind generator and ultimately uses the wind energy for moving.

Between sailing and what else do you want to draw a clear boundary?

Kaa

OK, this is a useful direction; let's have a look. First, it's not what *I* want; a definition doesn't exist to suit a single person's wishes. We don't define "bird" just to suit Mr Audubon's sensitivities.

Boundaries are good. For instance, a definition for "sailing" ought to separate drifting versus sailing, as you suggest. It ought to separate sailing from "wind powered vehicles," for instance (a wind turbine, afloat or ashore, charging batteries later used to power a runabout is a "wind powered vehicle". It is not a sailboat. Ask yourself why?)

Without a concept of stored energy--and a disallowance of same in "sailing" you wouldn't be able to delineate the two (I've talked about this earlier int he thread)

Problem here is we come back to descriptions. If I tell you I think sailing ought to discriminate between stored energy and non-stored energy, you can simply add it to your description, and we're only a tiny step closer to a definition (and that's presuming you actually agree that stored energy isn't "sailing" Some canting keel guys might disagree...) Definitions should be simple; "lift" is a force perpendicular to the flow of a fluid medium; "tangent" is the ratio of two sides of a triangle, etc.

"The exchange of momentum between two media and a vehicular device for the purpose of directed travel" might work. I started this thread, and didn't want to be presumptuous--and I didn't want to "defend" my own definition, since, after all, I hardly have the authority. There's been a lot of great input so far; I'll try to boil it down to a short description, and maybe we can pick at that.

Dave

[SailDesign]

Someone should perhaps ask the OP to fess up as to WHY he started this thread..... THat will give us all some idea of where he is going.
The fact that his handle is "Kiteship" might give some indication that he is seeking approval for calling a kite-powered ship a "sailing" ship - or not.
So, Kite, what is it?
I don't think for one minute that anyone is going to argue with a kite-powered boat being a sailing boat, but you never know. Insurance companies might argue it, coz they are as wierd as lawyers (apologies to any insurance folks in here) and need to create smaller pigeon-holes to exclude people from.
Personally, if it doesn't use a stored energy device for propulsion, then it must be a sailing boat/craft/ship, no?
And I do not exclude such things as canting-keel boats with engine-driven systems, because they CAN sail without the ebngine, just not as fast, and because the keel-canting mechanism on its own will not move the boat

[Kiteship]

Thought I'd been clear about that. No, I don't need validation regarding kites and ships--I'm OK with that (though I have in fact been told that kite sailing isn't "sailing!" I considered the source and took no offense... ;-) My signature is my business; see www.kiteship.com

I'm an amateur scientist (or heck, maybe I'm a pro--I get paid to do what I do), and like a lot of scientists, I find enjoyment in turning things over and taking them apart. I'm a long standing member of the Amateur Yacht Research Society, am in fact, running a parallel thread there right now. I take things apart so that I can develop a better understanding of the things around me, the better to design or discover new ways of putting things together, discover new things, and develop new insights about things I already "know" are true. (the cliche about "The older I get the less I am sure of" is absolutely true!) I've already unlearned several mis-truths since this thread started; I expect there'll be more.

(Just for the record, I've been sailing since I was little--maybe 40 years now. I sold my first design nearly 30 years ago; have been a pro boatbuilder, pro fisherman (offshore albacore jig boat), mechanic, designer, sailor and general layabout. Plus the usual carpenter, electrician, husband and father that fills the time for us all. I like kites, and other "unusual" approaches to sailing. I have a couple of patents in the field, and run a company trying to put kites onto ships. Mostly, I'm just curious. Drives the wife nuts--and some here, it seems.)

Thanks for your "wide" POV regarding sailing, SD, but even there you display the limits of your own sailing "box." Why d'you presume I'm only interested in sailing which involves wind over water? That's only one of at least 6 sailing contexts. The others are at least as fascinating--and as full of surprise traps, contradictions and opportunities, as the one we make our living with.

(And no, dammit, canters are *not* sailboats. Darn cheaters! Oh, sorry, was I being shrill there? ;-)

Dave

Someone should perhaps ask the OP to fess up as to WHY he started this thread..... THat will give us all some idea of where he is going.
The fact that his handle is "Kiteship" might give some indication that he is seeking approval for calling a kite-powered ship a "sailing" ship - or not.
So, Kite, what is it?
I don't think for one minute that anyone is going to argue with a kite-powered boat being a sailing boat, but you never know. Insurance companies might argue it, coz they are as wierd as lawyers (apologies to any insurance folks in here) and need to create smaller pigeon-holes to exclude people from.
Personally, if it doesn't use a stored energy device for propulsion, then it must be a sailing boat/craft/ship, no?
And I do not exclude such things as canting-keel boats with engine-driven systems, because they CAN sail without the ebngine, just not as fast, and because the keel-canting mechanism on its own will not move the boat

[longliner45]

ok I read your site ,,looks really cool ,you shold sell alot of them now that fuel prices are high ,,,I may get on for my boat ,,,,but as for sailing ,,you must be in controll of your vessal ,,free to go here and there ,,and against the wind,,,I can see it now,,500 ft of sail plus a spinniker ,,and the mother of all kites heading south on the trades,,,,,how much do these cost? longliner

[Kaa]

OK, this is a useful direction; let's have a look. First, it's not what *I* want; a definition doesn't exist to suit a single person's wishes. We don't define "bird" just to suit Mr Audubon's sensitivities.

Well, first, definitions can be useful to suit a single person and second, again, you haven't defined a conversation in which such a definition will be useful. I've talked about it a bit in a post above.

See, I think of definitions as being rather arbitrary. The fabric of reality is certainly not even and uniform, but overlaying mind-created concepts on top of it can be done in many different ways and the boundaries you draw are not necessarily well-defined.

People who come from math, or physics, or engineering backgrounds are usually uncomfortable with this fuzziness and arbitrariness. They tend to believe in objective "Truth" and in the existence of "correct" definitions. People who come from the humanities are, generally speaking, more cognizant of the fluid and uncertain character of maps that human mind uses to understand reality.

It seems to me that you are trying to get a physics-like definition for sailing and are unwilling to come to grips with the idea that the concept of sailing is broad, ambiguous, and likely means different things for different people. I continue to think that you can't produce a universal definition of sailing that will be equally useful anywhere. You need to specify a purpose and a context.

Without a concept of stored energy--and a disallowance of same in "sailing" you wouldn't be able to delineate the two

Consider a boat that has a windmill mechanically coupled to a propeller or a paddle-wheel. No energy is being stored. Is it sailing?

Problem here is we come back to descriptions. If I tell you I think sailing ought to discriminate between stored energy and non-stored energy, you can simply add it to your description, and we're only a tiny step closer to a definition (and that's presuming you actually agree that stored energy isn't "sailing" Some canting keel guys might disagree...) Definitions should be simple; "lift" is a force perpendicular to the flow of a fluid medium; "tangent" is the ratio of two sides of a triangle, etc.

Definition is a subtype of description. And simple definitions work only for simple concepts. By Occam's Razor we would *prefer* a definition to be simple, but a useful long definition is better than a short, but useless one.

"You should make it as simple as possible, but not simpler" :-)

Kaa

[MalSmith]

Consider the case of a Flettnet rotor, which is vertical cylinder that is rotated by some mechanical means. The Flettner rotor develops lift due to the magnus effect. Otherwise it behaves as and is used if it were a conventional sail. A Flettner rotor ship must be tacked into the wind like any other sailing vessel, and I think that most poeple would accept that the method of operation of a Flettner rotor ship is called sailing. Hence the need for the definition of a "sail" to be fairly broad.

Considering windmills, things get a bit nmore complicated. The blades of a traditional windmill are called sails. Under the terms of the broad definition for a sail that I have proposed previously, they are indeed sails. However, I don't think anyone would call the operation of a windmill "sailing". If you attach a windmill to a boat and mechanically link it to a propeller, are you "sailing" the windmill boat or not? Conventional fixed sail boats and a windmill boats are actually very similar. Both couple aerofoils to hyrofoils in order to be able to move in any direction including straight into the wind. The difference is that a windmill boat is a rotational device and a fixed sail boat is a linear device. Because the fixed sail boat is a linear device, the whole device must be moved in zig zag pattern (tacking) in order to advance straight into the wind. On windmill boat, the hull can advance satight into the wind because the sails and foils can be moved independently of the hull. Personally I consider a windmill boat to be a sailing vehicle. If you don't however, then the difference comes down to the fact that the fixed sail device must be tacked into the wind.

Mal.