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raaaid
07-31-2005, 11:27 AM
when navigating on a plane its necessary a coriolis correction of the course of the gyrocompas that increases with the speed and the farther of the equator you are

physics says that in the northen hemisphere water will tend to drain clockwise and in the southern counterclockwise

but the two toilets of my houses i have checked both create a vortex that goes counterclockwise though im in the northern hemisphere

even in the simpsons episode bart vs australia they ignore what physics say and explain it the other way around, water flush counterclockwise in the northern hemisphere and oposite in the south as lisa explains althoug she doesnt realize this is only in toilets for some strange reason

i believe this is a lie of the physicist in the known that earth could be acelerated by creating big toilet vortexes and therefore energy could be created from earths field consumming only gravity

the same they hide reactionless propultion when is obvious than an ice skater produces a forward thrust using only the lateral force of his skates which he moves towards the sides so the reaction of the forward thrust is not backwards as physics say but sidewards, you make a force sidewards and you go forward

this proves again two of the 3 biggest secrets to be free energy, from gravity for example, and antigravity contradicting newtons laws

im curious, what sense does your toilet flush and in what hemisphere you are?

Tully__
07-31-2005, 11:44 AM
First: Coriolis forces are so weak that the shape of the container and existing currents in the water are the determining factors for direction of draining in most cases.

Second: Coriolis vortexes derive their energy from the earth's rotation, not the other way around.

Third: The skater is applying a thrust (forget the direction, you're not up to vector calculus anyway) so his propulsion is not reactionless.

Fourth: Proper examination of Newtons laws in a 3 dimensional frame of reference leads us to EXPECT all of the circumstances you describe, they are not contradictory.

Tully__
07-31-2005, 11:46 AM
P.S. Toilets in my area flush in different directions depending on the shape of the bowl and the direction of the water coming from the nozzle. As I mentioned above the forces applied by those are orders of magnitude greater than coriolis and far outweigh any effect coriolos may have on the draining process. The same applies to kitchen sinks, buckets, baths, showers and all other fluid recepticals.

raaaid
07-31-2005, 12:21 PM
i think you are right and lisa as me wrong thanks for the info tully

by the way as for the skater problably you think is the same than skiing where you put the points towards the outside what would explain the thrust easily but this link stablishes clearly that the skates go parallel:
http://www.bcso.bc.ca/resources/Athlete%20Resources/Spe...g%20Drill%20Book.pdf (http://www.bcso.bc.ca/resources/Athlete%20Resources/Speed%20Skating%20Drill%20Book.pdf)

and the fact that they go parallel makes imposible to explain how the thrust is produced

i mean if you dont have a starting speed how could you produce thrust with the skates parallel from 0 km/h

but it works once you have speed, i have tested itmyself

Ralph_Phillips
07-31-2005, 12:41 PM
Tully's got it right above. Existing motion of water in a container determines in which direction it will drain. The gag in the Simpson's episode is the US govt. installs big clunky machines on the Australian embassy's toilets to make them drain in the proper "American" way.

Being that "The Simpson's" is a cartoon should preclude anyone from thinking they employ real world physics in the show. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif I mean, Lisa also invented a perpetual motion machine and Homer's traveled back in time.

But you CAN make draining water reverse direction if you stir it the other way. No big deal.

Also, the skater provides the thrust. Skates and ice are not frictionless. Very slippery, yes, but not frictionless. As I understand it, skates actually slide on a thin film of water between the ice and the skate caused by the skater's mass pressing down on the ice through the skate. There are some other things that come into play, but skating is just a fancy way of walking on ice. So no magic transfer of energy or anything there.

Respectfully,

NonWonderDog
07-31-2005, 01:24 PM
So, is Raaaid just messing with us, or does he actually believe that all physics is a lie?

The "coriolis force" is not a real force. It is a calculation concept used to describe a frame of reference on the spinning earth. Instead of saying that earth spins beneath the atmosphere (which is what is actually happening), we sometimes want to pretend that the atmosphere is being pushed at uneven rates around a static earth. This can greatly simplify calculations.


Skates are shaped the way they are so as to make you go forwards when you push off diagonally. The flat side of the forward skate provides a frictional force opposite the sideways component of your push. The small tip of the skate gives very little resistance to the forward component of your push, so you move forwards.

If you try to skate like this with shoes on, you will slide sideways and fall over.

Tully__
07-31-2005, 01:38 PM
Originally posted by raaaid:
i think you are right and lisa as me wrong thanks for the info tully

by the way as for the skater problably you think is the same than skiing where you put the points towards the outside what would explain the thrust easily but this link stablishes clearly that the skates go parallel:
http://www.bcso.bc.ca/resources/Athlete%20Resources/Spe...g%20Drill%20Book.pdf (http://www.bcso.bc.ca/resources/Athlete%20Resources/Speed%20Skating%20Drill%20Book.pdf)

and the fact that they go parallel makes imposible to explain how the thrust is produced

i mean if you dont have a starting speed how could you produce thrust with the skates parallel from 0 km/h

but it works once you have speed, i have tested itmyself

Did you actually read that document raaaid? It describes the basic position (gliding without pushing) as skates parallel, but the section devoted to pushing has the skates at 90 degrees to each other and 45 degrees to the direction of travel; IE: NOT PARALLEL

Freelancer-1
07-31-2005, 01:43 PM
Forget skating.

How about sailing upwind.

There's something strange about using the breeze that's blowing toward you to power yourself against it.

Think on it Raaaid, and see where it leads you.

Freelancer

raaaid
07-31-2005, 01:46 PM
"Skates are shaped the way they are so as to make you go forwards when you push off diagonally.The flat side of the forward skate provides a frictional force opposite the sideways component of your push. The small tip of the skate gives very little resistance to the forward component of your push, so you move forwards. "

yes it would worked this way if you placed the skates diagonally but according to my link they go p rallel

when you walk you advance because the earth is pushed slighlty backwards, thats the reaction

but keeping the skates perfectly parallel is just imposible to push the earth backwards, only sidewards, but you still get thrust by pushing the earth sidewards not backwards as it should be the reaction, in other word the reaction is not backwards is sidewards

by the way i really like people knowing stuff around here

arcadeace
07-31-2005, 01:49 PM
Raaaid you€re more clever than I thought and some not so in a curious way lol http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Tully__
07-31-2005, 02:00 PM
Originally posted by Arcadeace:
Raaaid you€re more clever than I thought and some not so in a curious way lol http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
Not much of a skater though http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

raaaid
07-31-2005, 02:12 PM
i think the 45º position is just for starting:
"Determine if the athlete is more comfortable with the T start (feet in letter T or the parallel start (both feet 45 degrees to the start line)."

"When starting:
€ Skates should be parallel and about 45 degrees from the starting line."

this is what you do once you started:
"Drills for basic position:
Take a few steps and then glide down ice in basic position. Check for parallel skates and straight ankles.
Have skaters rock back and forth in the basic position to practice changing the center of gravity."

"The warm up should be used as a time for the athletes to get used to their skates, the ice and the environment. The warm up should be done at an individual pace with the emphasis placed on proper technique.Position both skates parallel, pointing straight ahead in the direction of travel.
4. Flex knees about 100 degrees, placing the thighs almost parallel to the ice.

i suppose you dont see sense either in getting thrust with the skates parallel, is what happens to me

as for the ship going against the wind is perfectly explainable with vectors if you consider that the ship goes on rails would be the same than if you put the skates 45º apart

arcadeace
07-31-2005, 02:15 PM
Originally posted by Tully__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Arcadeace:
Raaaid you€re more clever than I thought and some not so in a curious way lol http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
Not much of a skater though http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>

Proof of a depraved life http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Tully__
07-31-2005, 02:53 PM
...a few steps and then glide down ice in basic position. Check for parallel skates...

GLIDE with skates parallel, not push http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

By the way, have you ever ice skated? ... I have. Trying to push with skates parallel to each other and intended direction of travel will get you a lot of side to side motion and tired legs, but not much forward motion.

LEBillfish
07-31-2005, 03:05 PM
Originally posted by Freelancer-1:
How about sailing upwind.

There's something strange about using the breeze that's blowing toward you to power yourself against it.
Freelancer

That is actually easy if you consider the "shape of a sail"....Some demonstrating the concept more then other "planes".

Treetop64
07-31-2005, 03:17 PM
"...I now have this inexplicable urge to go out and buy a pair of really pretty pink ice skates..."

-HH- Beebop
07-31-2005, 09:50 PM
O....M....G....!

Now we are discussing which way water flows down a toilet, skating and sailing!

Well it sure beats the usual uber/porked/"X" won the war threads.

http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

raaaid
08-01-2005, 06:24 AM
i did only once ice skating and did nothing but fall donwn

but i took several years courses of roller skating when i was a kid

when we had to make a qualifying lap my brother and i knew that the best way to do it was to accelerate from 0 like if you were running holding on the brakes of the tip toes because the circuit was to short to gain speed

from 0 to a certain speed you hold on the brakes using reaction then once you have speed you use the position of balancing the arms to the sides and pushing, with the skates parallel, to the sides now the reaction goes to the sides not opposite contradicting newtons laws but it works try it

Tully__
08-01-2005, 08:15 AM
Originally posted by raaaid:
...then once you have speed you use the position of balancing the arms to the sides and pushing, with the skates parallel, to the sides now the reaction goes to the sides not opposite contradicting newtons laws but it works try it

If you were to analyse the motion with a slow motion camera you would find the skates were NOT parallel, but angled slightly out from your direction of travel. Next time there's a speed skating competition on your local sports channel pay close attention. Really close attention.

Zeus-cat
08-01-2005, 09:10 AM
Toilets are overmodelled. So is ice.

Zeus-cat

Airmail109
08-01-2005, 09:23 AM
I think raaid is one of those nutters wholl accidently stumble upon dark matter or something in the future....hes kinda got a really stupid intelligence. http://forums.ubi.com/images/smilies/34.gif

WWSensei
08-01-2005, 09:34 AM
Originally posted by Aimail101:
I think raaid is one of those nutters wholl accidently stumble upon dark matter or something in the future....hes kinda got a really stupid intelligence. http://forums.ubi.com/images/smilies/34.gif

No, not likely. Basing an understanding of physics on a Simpson's cartoon isn't an indication of subtle genius--just that PT Barnum was right about who is born every minute.

nicholjm
08-01-2005, 12:17 PM
The resoltion of forces between coriolis, pressure gradient force and friction is what is responsible for the wind direction relative to high and low pressure areas, and as the relationship changes (i.e. friction becomes weaker with altitude) wind direction changes quite predictibly with altitude. Go check winds aloft forecasts. If anyone wants more information on this subject let me know.

GRYPHON_401Cdn
08-01-2005, 08:28 PM
With reference to the insight shown by the original poster:

Isn't alcohol wonderful.....?

Tully__
08-01-2005, 11:42 PM
Originally posted by GRYPHON_401Cdn:
With reference to the insight shown by the original poster:

Isn't alcohol wonderful.....? It's nothing to do with alcohol, that is one of his more lucid posts... http://forums.ubi.com/images/smilies/blink.gif

wayno7777
08-02-2005, 01:13 AM
What a quark. Now I've got a headache...

raaaid
08-02-2005, 06:22 AM
tully maybe you are right and the skates must be kept a little open

but this would mean the link i showed to be wrong as it clearly states they are kept parallel and also that you would get no thrust at all if you pushed with the skates parallel as my link states

the problem is that i know by experience you keep the skates parallel and you get a lot of thrust forward pushing sidewards

in fact if you open the skates you wont only not get thrust at a speed but you will probably also fall down

Tully__
08-02-2005, 05:44 PM
Originally posted by raaaid:
..but this would mean the link i showed to be wrong as it clearly states they are kept parallel...
The article isn't wrong, you're misreading it. All references to parallel are intended only for glide (coasting). At no time is the term parallel used when describing the skater pushing.

... i know by experience you keep the skates parallel... Not quite parallel, the must be a little open. It may seem parallel, but I suggest if you still have skates that you put them on and give it a try. If possible, video tape it.

B0lter
08-02-2005, 09:23 PM
It is just as Tully says. Even if you push is at an angle to your direction of travel, there will be a longitudinal component, and a perpendicular component to the force aplied. So your effective longitudinal thrust would be Force * Cos/Sine of the angle; sine or cosine would depend on which axis of reference you're using to mesure the angle off, longitudinal or perpendicular. All of this is perfectly consistent with Newton's and thermodynamic's laws.

Raaid, if you're truly interested in free energy look up Tom Bearden's "energy from the vacuum". He is the leading theoreticist on overunity. You will find that this technology is not being suppressed, just not federaly funded (yet.) You will also find out that there is no such a thing as free energy, but just a tapping of previously undetected energy in the vacuum, which scientists are finding out, is jammed pack full of usable energy. This does not violate thermodynamics laws because the energy is already present in the "closed" system.

For more information on the "antigravity" effects observed in gyroscopes (your previous topic), and more recently in particle accelerators, you should turn to Robert Forward's "guidelines for antigravity" c.1963. There you will find that this effect is consistent with an often overlooked portion of the Special Relativity Theory. Again, this is known and well documented physics.

Truth is indeed stranger than fiction. No need to go all X-files about exciting scientific developments.

raaaid
08-03-2005, 01:16 PM
today ive gone to the beach to do some wind surfing and paid special attention to the skaters and tully was partly right and i was partly wrong, most people opened the skates to thrust but i saw one guy who kept them perfectly parallel so even parallel it produces thrust you should accept this

the component of pushing sidewards certainly is diagonal so vectorially it works, appears a reaction

but think it other way imagine you walk and you push back the earth a big deal(reaction) now you skate with the skates parallel and push the earth sidewards a big deal (reaction sidewards), theres no way with the skates parallel when you thrust you push the earth backwards, you only move it sidewards, taking into account theres no friction in the longitudinal axe you cant move it backwards

somebody else must see in his mind that with the skates parallel theres no way to push the earth backwards, tully sees it clearly thats why he doesnt accept you can produce thrust skates parallel and ignores that what my link says basically is:

you start with the skates 45º to the start line, parallel skates or them in the T position

once you gained enough speed you swing with parallel skates besides many crab,but parallel.

i know about bearden there are many more try the disclosure project, 400 witneses say what really is going on, my favourite is tesla

dou you think that if the water engine worked,getting energy from nothing because you use water and you get water in the exhaust, a perpetual movile, was posible the petrol companies would let it out or the bankers, engine that would allow to transform the plumb into gold in a particle accelerator disposing of undefined energy, do you really think that the people in power would risk the tables being turn?

FI.Spitsfire
08-03-2005, 01:59 PM
AHHH, I'm on summer hols, stop remending me of A-level physics! http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif
While I havent read all the stuff here, my limited grasp tells me you have the basics... http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif


-runs-

B0lter
08-03-2005, 04:08 PM
imagine you walk and you push back the earth a big deal(reaction) now you skate with the skates parallel and push the earth sidewards a big deal (reaction sidewards), theres no way with the skates parallel when you thrust you push the earth backwards, you only move it sidewards, taking into account theres no friction in the longitudinal axe you cant move it backwards

You are failing to take into account the fact that your forward motion is, in escensse, the long arm of the vector analysis, and your "sideways" pressure makes the perpendicular component of the trust vector. Maybe you're thinking Cos of 90deg is zero, so there is no longitudinal thrust component, but you got to realize you're not stationary. If you're moving forward, there is no way that you can push your skates outward and keep your feet from even an infinitesimal lateral drift. And if there is even a micron of lateral movement, then there is a perpendicular component, and thus a longitudinal force component however small. The skater's forward motion is the longitudinal axis, the sideways pressure must give a very small lateral movement which is the perpendicular axis, so vector analysis apply.

Besides, there is friction, a lot of it. Gravity accelerates your mass and gives it weight. That force in turn is applied accross the very small area of the skate blade. Pressure is force over area. A lot of force and very little area make a lot of pressure. That pressure melts the ice; thermal energy loss right there. Ice water does have a non zero dynamic friction coeficient; loss of energy again. You can hear the skates scrape the ice; energy loss due to sonic radiation. Atmospheric density resistance is present as well. Raaid, your skater is bleeding energy like a sieve, and the only source to replenish that magnitude of loss is the motive force of the skater.

Yes, Newton's third law states that "every action has an equal and opposite reaction", so yes, the Earth does match your force upon it. It, however, does not give you any free energy. "Backwards" or "sideways" are not applicable concepts when describing an interaction with Earth's crust, just "downwards", since it is the effect of your mass accelerated through the Earth's center of gravity, but applied against its surface. Any force not aligned with this vector is fully explainable by vector componets of a given off-angle.

I'm not saying that the concept that you're trying to get accross is wrong, in fact I just don't get your point. I'm only saying that your skater analogy does not support whatever point you're trying to make.

ElektroFredrik
08-04-2005, 10:42 AM
May I recommend a very good skating simulator
with highly realistic physics. As real as it gets!

http://www.whatisthe2gs.apple2.org.za/the_fairway/game_pages/game_boxes_large/skate_or_die.jpg

Also a documentary about the hazards of skating
with skates parallel.

http://haushoej.dk/Graphics/Products/7910.jpg

Hoatee
08-04-2005, 02:16 PM
Fewer planes means that more code could be written for other stuff. So it could still be runnable (who knows? - we'll just have to wait and see).

Personally, I have a hunch (anyway a hope) that the physical world will be full scale vertically. You'll see that'll make a world of difference to the flying experience.

telsono
08-05-2005, 03:57 PM
As to sailing into the wind, modern sail technology has improved very much to allow greater efficiency but I still don't think that you can sail directly into the wind. That was a state called "caught in irons" as the wind would try to stop your motion. Sailing close to the wind (sailing straight into the wind) is called "tacking" which is not as efficient as having the wind to your back. When you tack, you usually change direction to the right and left of the wind's direction to keep your course as true as can be done. Otherwise you would not keep on the course (vector) that you wanted to be on.
One of the tricks of the old frigate captains in the age of sail was to sail as close to the wind as possible by tacking to catch the other vessel "in irons" then have the advantage of "crossing the T" across your opponents bow with your full broadside.
There may be others out there with greater sailing experience than I have, but that is my brief knowledge on it.

Capt.England
08-05-2005, 04:36 PM
with all this talk about toilets, I can see this thread going down the pan! http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif

WB_Outlaw
08-05-2005, 09:15 PM
raaid,
What about the "british columbia special olympics speed skating drills book" makes you believe it is a scientific document explaining physics and reality?

It is a book designed to help non-professionals teach handicapped kids how to skate and compete to the best of their abilities.

Reading this like it was written by Newton himself is so totally assinine that you must be joking. However, just in case, I will clear it up for you...



Commandment #3 does not imply that you can increase your speed by following it. It merely states the most efficient position for minimizing energy loss.

"Drills for basic position" cleary states that the skater should "Take a few steps and then glide down ice in basic position". The checking for parallel skates SHOULD ONLY BE DONE FOR THE GLIDE PART, NOT THE STEP PART. Note that "STEP" does not imply that you should push outward with your skates. It implies that you should STEP!!!!!!!!!!

"When Starting" section clearly states that your skates should be parallel to each other and 45 DEGREES FROM THE STARTING LINE. READ THAT CAREFULLY. Your skates are NOT POINTING IN THE DIRECTION YOU ARE GOING TO MOVE. That 45 degrees is where your forward component of force comes from.

Now, watch a speed skating event. Aside from the start and stop, it consists of alternating "pushing" and "gliding". The book clearly states that the push is accomplished with the skates in the T-position and a glide is accomplished with the skates parallel to each other.

PLEASE STOP NOW!

Thanks,

Outlaw.

raaaid
08-06-2005, 04:44 AM
Basic Body Position on Ice- Ten Commandments
1. Keep feet shoulder width apart, providing a stable base of support.
2. Maintain ankles in a neutral position so that you are directly over the top of the blade.
3. Position both skates parallel, pointing straight ahead in the direction of travel.
4. Flex knees about 100 degrees, placing the thighs almost parallel to the ice.
5. Center the body weight over the middle to back 1/3 of the skate
6. Flex the trunk forward from an upright position about 60 degrees with a slight rounding of the back.
7. Rest both arms comfortably on the middle of the lower back.
8. Hold shoulders level ( as viewed either from behind or in front) and pointed straight ahead ( no rotation of the spine and upper body)
9. Hold head upright, with eyes looking ahead.
10. Keep the body as relaxed as possible.
Speed skating can be broken down into six major components : balance/standing, gliding, pushing, stopping, turning and skating backwards. Each skater will progress through these skills at their own rate, however, early emphasis should be placed on balance/standing and gliding.



right, so you keep the thighs parallel to ground to coast

raaaid
08-06-2005, 04:50 AM
"Now, watch a speed skating event. Aside from the start and stop, it consists of alternating "pushing" and "gliding". The book clearly states that the push is accomplished with the skates in the T-position and a glide is accomplished with the skates parallel to each other"

saying that you push in T position or 45º parallel skates and then glide in parallel position is senseless unless you accept you can thrust while gliding with parallel skates so you would be proving me right:

almost no friction in the longitudinal axe and you get a lot of thrust forward by pushing perfectly sidewards anybody understands it i dont

WB_Outlaw
08-06-2005, 08:45 AM
Originally posted by raaaid:
saying that you push in T position or 45º parallel skates and then glide in parallel position is senseless unless you accept you can thrust while gliding with parallel skates so you would be proving me right:

Why do you believe that you must produce thrust while gliding? By DEFINITION gliding is done WITHOUT THRUST! You are not even reading the post or the document you linked to. Please look at the 45 degree statement again and draw a free body diagram and you will see what I'm talking about.



Originally posted by raaaid:
almost no friction in the longitudinal axe and you get a lot of thrust forward by pushing perfectly sidewards anybody understands it i dont

NOWHERE IN THE DOCUMENT DOES IT STATE THIS!!! WTF are you reading?




Originally posted by raaaid:
right, so you keep the thighs parallel to ground to coast

NO!!!!!!! You speak as if THIS IS A TEXT BOOK ON THE PHYSICS OF SKATING!!!!!! It's NOT. It's merely a GUIDE BOOK ON THE BEST TECHNIQUES FOR TEACHING KIDS HOW TO SKATE. According to you, the ONLY way a skater can coast is by keeping their thighs parallel to the ground because that's what this book said.



I was incorrect in saying that you always push in the T-position. I believe that's for starting only. At speed it would be difficult at best to move your push foot to 90 degrees and back.

There has to be a language barrier here or raaaid is the Ashton Kutcher of the IL-2 forums and we are all being punked.


-Outlaw.

Treetop64
08-07-2005, 04:45 AM
I think we need another can of "Raid"... http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Tully__
08-08-2005, 12:01 AM
Raaaid, as skate speed increases skates come closer to parallel, but never quite make it. If you tried skating with skates parallel you'd look like a saddle sore cowboy http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif.

Like this:

http://jennirivers.actewagl.net.au/skate.jpg

If you still have your roller skates, I'd like you to try an experiment. First, stand still with your skates perfectly parallel and push out. You wont move if you have it right and your skates are parallel.

Now move the front of your skates slightly out and push out. You will slowly start to move, accelerating from a standstill as your skates roll away from each other.

flyboy_112th
08-08-2005, 09:02 AM
Just to add to the confusion:

Regarding Skating, it IS possible to produce forward thrust with the skates parallel, but not parallel with the direction of motion. You can use your weight. Imagine if you will pointing both skates parallel, but angled to the left of the path you wish to take.

If you now fall to the right there will be a movement of your centre of gravity to the right and a concomitant force pushing your skates to the left and therefore forward because of the angle of the skates.

Bringing this back into the world of not falling over, what you effectively do is keep your skates parallel to each other but transfer weight from the left to the right skate. Both skates remain parallel, you go forwards, but the path the skates actually take is sinusoidal about the direction of travel. It is the weight transference and the rocking motion that provides the forward thrust.

2) There are a few components responsible for "beating" (sailing into the wind), and no sailing boat can go *directly* into the wind, but at an angle to it. In the J24 I used to sail, the best upwind speed (tradeoff between actual speed and angle towards wind) was at an angle of about 42 degrees to the true wind, which corresponded to a typical apparent wind about 30 degrees off the nose (the forward motion of the boat changes the apparent direction of the wind).

What happens is that there is a force generated by the sail which is in a direction that is just forward of the beam (the 3-9 line), which resolves into a forward and a sideways component. It is that forward component that drives the boat forward (upwind though not directly into the wind) and the sideways component acts about the centre of gravity (much lower than the centre of effort of the sail) to cause the boat to heel over (roll to one side). Since in most modern sailing boats the vast majority of the weight is in the keel, the rolling moment is resisted by the weight of the keel.

IN summary there is a thrust vector generated by the keel in resisting sideways movement and a lift vector generated by an area of low pressure behind the sail.

It's worth noting that making progress upwind is almost impossible for more traditionally clothed square riggers, and it was only with the installation of triangular sails forward (Genoas , Jibs, Spankers and the like) and aft (mizzen) that real upwind progress started to be made.

Tully__
08-08-2005, 09:14 AM
But still not parallel to direction of travel.

NonWonderDog
08-08-2005, 10:47 PM
I just want to say that racing sailboats and similarly rigged boats can actually sail faster on a tack into the wind than they do sailing with the wind. Much faster.

I really want to see where raaaid takes that.

raaaid
08-09-2005, 06:23 AM
tully i dont need to put skates on to test that you are right

but theres a third test that would be gaining some speed to push sidewards with the skates parallel to see if you gain speed or not, my experience and that web say so, anyway i have my doubts so ill have to check it

as for the ship tacking going faster the reason is simple

tacking is like going croswinds if the lateral resistance of the keel is infinite and the longitudinal resistance 0 the ship could reach infinite speed is the same for tacking

ChileanChe
08-09-2005, 07:12 PM
Originally posted by raaaid:
tully i dont need to put skates on to test that you are right

but theres a third test that would be gaining some speed to push sidewards with the skates parallel to see if you gain speed or not, my experience and that web say so, anyway i have my doubts so ill have to check it


as for the ship tacking going faster the reason is simple

tacking is like going croswinds if the lateral resistance of the keel is infinite and the longitudinal resistance 0 the ship could reach infinite speed is the same for tacking

But when the boat is going downwind the keel presents the least resistance to the wind (edit: I meant to write *water,* not wind.) That is also when the boat goes slowest. I am talking about sloops, which have the main sail behind the mast and the jib ahead of it.

Tully__
08-09-2005, 11:00 PM
Originally posted by ChileanChe:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by raaaid:
tully i dont need to put skates on to test that you are right

but theres a third test that would be gaining some speed to push sidewards with the skates parallel to see if you gain speed or not, my experience and that web say so, anyway i have my doubts so ill have to check it


as for the ship tacking going faster the reason is simple

tacking is like going croswinds if the lateral resistance of the keel is infinite and the longitudinal resistance 0 the ship could reach infinite speed is the same for tacking

But when the boat is going downwind the keel presents the least resistance to the wind (edit: I meant to write *water,* not wind.) That is also when the boat goes slowest. I am talking about sloops, which have the main sail behind the mast and the jib ahead of it. </div></BLOCKQUOTE>
It's because the shape of the sail is much more efficient at producing thrust at tack angles between about 90-50 degrees into the wind (depending on specific sail design). The combination of increased "airspeed" and lower "angle of attack" allow a greater increase in thrust than the drag penalty from the high cross forces on the keel.

ChileanChe
08-10-2005, 06:07 AM
I know, Tully http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif I'm just pointing out to raaaid that his theory doesn't actually explain real behavior.

Zeus-cat
08-10-2005, 10:59 AM
QUOTE]I know, Tully I'm just pointing out to raaaid that his theory doesn't actually explain real behavior.[/QUOTE]

DANG! How come no one ever thought of that before! (sorry, couldn't help myself)

Zeus-cat

ChileanChe
08-10-2005, 03:30 PM
I'm a hopeful sort of fellow . . . http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif

Platypus_1.JaVA
08-10-2005, 04:14 PM
Well, it is perfectly possible to move yourself from a standstill with your skates parallel. Just jump off a D@amn building!

ChileanChe
08-11-2005, 07:35 PM
Originally posted by Platypus_1.JaVA:
Well, it is perfectly possible to move yourself from a standstill with your skates parallel. Just jump off a D@amn building!

Indeed. Or, just push off with one skate. Don't skats have "teeth" on the toes for that purpose? The skates would still be parallel . . .

Tully__
08-12-2005, 05:27 AM
Originally posted by ChileanChe:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Platypus_1.JaVA:
Well, it is perfectly possible to move yourself from a standstill with your skates parallel. Just jump off a D@amn building!

Indeed. Or, just push off with one skate. Don't skats have "teeth" on the toes for that purpose? The skates would still be parallel . . . </div></BLOCKQUOTE>

Using the brakes/teeth was not part of the discussion, but yes, using them would allow you to push while keeping the skates parallel. It wouldn't do you any good if pushing directly out to the side as discussed here (may even slow you down a tad http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif)