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geochuck
January 21st, 2008, 10:17 AM
I have been studying videos of swimmers and find what was once called the "S" stroke has almost disappeard.

I have noticed that flyers use it. But crawl swimmers have modified it so much that it is almost gone.

Has it been replaced completely or was it an optical illusion? Did underwater film show us it did not exist.

Blackbeard's Peg
January 21st, 2008, 02:45 PM
GP, I dont know if this is an older term, or if I know it by something else. Could you perhaps explain in a bit more detail what is this "S" stroke? I don't believe I've ever heard of it.

cowsvils
January 21st, 2008, 03:24 PM
I believe what he is referring to is a stroke where instead of pulling straight back, you pull out at the catch, then back in towards your body, and then back out to finish, thereby making an S with your arm. I think someone discovered that it was somehow quicker, I think it was through analysis of sea turtles. From what I saw at my brief look at butterfly swimmers is that they use more of a V stroke than a true S, I wouldn't be surprised if this has something to do with hand position as they exit the water.

Glenn
January 21st, 2008, 04:04 PM
I reviewed a video on swimming freestyle with Eddie Reese a year ago or so for our LMSC's newsletter insert to the USMS Swimmer magazine. I remember Reese saying that the "S" pattern is more of a wiggle today than the old "S" we were taught. So yes, Geochuck, you have observed correctly that it's use is not as prevelant as it used to be. I have changed my stroke so that I am doing more of a wiggle and not a giant sweep in toward the body.

blainesapprentice
January 21st, 2008, 04:08 PM
remember the good ol' key hole part of the freestyle pull--the underwater pull portion of freestyle that they use to teach. Last year was the first year that someone mentioned to me that that was an expired practice. Now apparently it is believed that a straight pull underwater is more effective.

geochuck
January 21st, 2008, 04:15 PM
Thanks for your responses, I am a little late coming back to answer or reply today. Chuckie and I are baby sitting our grandson. He insists on high 5ing me every few minutes.

When Councilman described it it was a very aggresive huge "S". I was a bent arm swimmer and did not do these major swing out swing in and out again things. Lot's of people interpreted the "S" as moving the hand and forearm position into be in fresh water. Not really grabbing and holding the water.

geochuck
January 21st, 2008, 04:25 PM
The reason I brought this subject up, I was at the pool the other day and watched the swim coach doing some stroke correction. He was teaching an exaggerated form of the "S" Stroke which to me is a no, no. I really had to hold my big mouth shut.

Allen Stark
January 21st, 2008, 04:40 PM
As I understand it,Councilman first observed that many world class swimmers where using and S shaped pull in free and fly. He variously hypothesized that it was to be more in still water and to increase lift propulsion.In an effort to generate more lift propulsion the S became exaggerated.then the Australians begin having success with a straighter pull and emphasizing EVF.Many coaches began to think that drag was more important than lift for propulsion so the S is phasing out.As to the underlying question about lift vs drag,as far as i know the definitive studies have not been done.

KaizenSwimmer
January 21st, 2008, 04:43 PM
I think it's possible that the freestyle pull, as swum today, may be completed in a straighter line than was true 40 years ago, but I think the more significant explanation is that swimmers and coaches finally realized that the "S" in the stroke was a matter of function, not intent.

If you intend to stroke in a straight line, your hand would still be seen by an observer to move in a somewhat curving path, relative to the pool bottom. This is because the hand that feels as if it's moving in a straight line - relative to the body - actually follows a curving path when body rotation is factored in.

Observers saw this when studying film in the 50s and 60s and dutifully reported those observations. To an audience that embraced them and dutifully practiced "S-strokes." Little did anyone realize that the "s-stroking" swimmers who had been observed were not giving any conscious thought to doing so. It simply happened.

When swimmers tried to move the hand in an S, they often ended up with an ineffective, exaggerated version.

Keep in mind however that Ian Thorpe had a honking big outsweep at the beginning, which accommodated his extraordinary upper arm rotation to a fingers-down, elbow-up catch. I always wondered what was going through his mind as he did this.

tomtopo
January 21st, 2008, 04:57 PM
Sculling or the "S" in swimming is important to peak swimming efficiency but it's been over-used and over-taught. It's important because the movement of the hand toward and away from the mid-line of the body allows the hand to move into still water (non-turbulent) and away from turbulent water (created by moving forward and by the hand itself). Keeping the hand moving through still water helps the hand leverage water (increases resistance or drag).
I think the biggest flaw in swimming is dropping the elbow but next to that it's gotta be swimmers who over-emphasize the "S" (it drives me crazy because it so hard to correct) so coach's who teach it - STOP!
An EVF should being emphasized much more because it's so hard to teach and to learn and so critical to swimming speed. Concentrate on EVF during every practice and forget the "S" (swimmers do the "S" naturally anyway).
Coach T.

knelson
January 21st, 2008, 05:33 PM
Sculling or the "S" in swimming is important to peak swimming efficiency but it's been over-used and over-taught. It's important because the movement of the hand toward and away from the mid-line of the body allows the hand to move into still water (non-turbulent) and away from turbulent water (created by moving forward and by the hand itself). Keeping the hand moving through still water helps the hand leverage water (increases resistance or drag).

I'm not sure I buy this. After all, we know that swimming in turbulent water (i.e., another swimmer's wake) actually makes you swim faster, so why should you want your hand to always be in still water? My gut feeling is the s stroke is more the result of biomechanics in that it allows the hand to be at its optimal angle of attack with respect to the water for as long as possible as the rest of the body rotates throughout the stroke.

geochuck
January 21st, 2008, 05:51 PM
Now are we saying the S stroke is an optical illusion?

The stroke I use is truly an S stroke because it does move into fresh water?

The arm as I pull certainly moves into fresh water all through the stoke, it does not stay on the same plain.

When swimmers did not roll like we do now it must have truly been an S stroke.

But I have always had a shoulder roll as seen in my 1956 swimming picture.

See it here http://forums.usms.org/showthread.php?t=7178&page=4

knelson
January 21st, 2008, 06:33 PM
Now are we saying the S stroke is an optical illusion?

No, as Terry said the swimmers didn't realize their hands were actually following an "S." They thought they were pulling straight, but the film showed a curved pattern to the pull. After discovering this, many coaches taught their swimmers to intentionally follow an S and this resulted in an exaggerated S.

geochuck
January 21st, 2008, 06:36 PM
So an I stroke is really an S stroke?

quicksilver
January 21st, 2008, 08:07 PM
So an I stroke is really an S stroke?




The S pattern was a more obvious sculling motion.
Today's freestylers may seem to be pulling straight back...but they're still sculling.

The hands are changing angles and pitch to hang onto the initial entry catch...and pull themselves past it.



http://www.youtube.com/watch?v=KhQfPokRMA0&NR=1

Allen Stark
January 21st, 2008, 08:20 PM
Kirk,you are right that you can move your hand through moving water faster than still water,but you will not generate as much thrust.The moving water provides less purchase to push against.It's like climbing a rope that is run through a pulley instead of fastened to a fixed point.You might be able to move the rope fast,but you couldn't climb it.

LindsayNB
January 21st, 2008, 08:42 PM
Allen, I interpreted Kirk to be referring to swimming faster when drafting off another swimmer. While it's true one moves forward faster when drafting despite swimming in more turbulent water I don't think the reasoning holds, swimming in a draft is like swimming downriver, the extra speed comes from the water you are swimming in moving in the same direction.

I think it is useful to think about the movement limitations of the human arm, if you consider the hand and forearm as all one big paddle then the path of the elbow largely determines the path of that paddle. If you think of the shoulder as a universal joint then the set of places you can position your elbow is basically a sphere, any movement of the elbow is going to be an arc not a straight line, so one can at least partially explain a curved path without resorting to nonsense like hands acting like airfoils; and still versus moving water may or may not be an issue. If you go on to look at how various muscles can contribute to greater or lessor degrees when the arm is in various positions you can find some additional explanations for certain paths.

I don't know if any of these factors will help anyone swim better, but if one is going to discuss the whys of the issue, I think these basic biomechanical issues deserve consideration.

geochuck
January 21st, 2008, 08:53 PM
You guys are really coming out of your shells and making some great statements. I know what I believe, I use the moving water no matter which way the water goes to my advantage.

mermaid
January 21st, 2008, 09:09 PM
I'm with Coach T & Terry on this one!

tomtopo
January 21st, 2008, 09:28 PM
I'm not sure I buy this. After all, we know that swimming in turbulent water (i.e., another swimmer's wake) actually makes you swim faster, so why should you want your hand to always be in still water? My gut feeling is the s stroke is more the result of biomechanics in that it allows the hand to be at its optimal angle of attack with respect to the water for as long as possible as the rest of the body rotates throughout the stroke.
--------------------------------------------------------------------------------
Eddie currents or the water that moves around a boat as it moves through the water is moving water, and the vortex behind the hand or paddle-wheel as it pushes water is another current of moving water; in both instances, a hand or paddle loses drag or it's ability to hold water or leverage it if it moves through that moving water or creates a vortex by moving water directly backward.
The pitch of the hand is ineffective unless it's moving toward or away from the mid-line (sculling). The hand and forearm are in it's most propulsive position when it is directly pulling backward until a vortex is created. Like a paddle-wheel, a constant movement backwards creates currents of moving water (behind the paddle) and unless the boat keeps touching the still water ahead of the paddle, it slips.
A hand that moves back and forth with a 45 degree pitch produces lift forces (critical in water ballet) but offers much less propulsive force in the free, back, fly and has more impact in the breaststroke. The pitch does however allow the hand to move back into still water which allows the hand to maintain effective drag or leverage.

Now as to why you swim faster when you swim behind someone, it's because air and water are both fluids; And just like bikers, and race car drivers who both shield and suck the person behind them, so are swimmers helped when they swim closely behind another swimmer (try touching my feet a few times and see what happens) - anyway the currents important to swimming are eddy currents and vortex currents (and others I'm sure).
__________________

geochuck
January 21st, 2008, 09:36 PM
Mermaid. My reason for presenting the ??? is not that I don't know the answer. I was disgusted with what I saw at the pool I swim in and what they are teaching in the pools. I also watched a swimming class a few days earlier and watched a redcross swimming instructor teaching this same exagerated "S" stroke to little kids. This instuctor was the one coaching competitive swimmers and teaching the same stuff.

I wanted people like Terry and coach Tom to respond and give their explanations and their beliefs. I think you probably know what most of my ideas are. All of the answers are good but is there a right answer???

LindsayNB
January 21st, 2008, 10:00 PM
Leaving the topic of S pulls but staying on the topic of moving water, it seems to me that there ought to be something interesting that could be learned by comparing tethered swimming to regular or assisted swimming. When you get to the end of the tether you are swimming in almost still water (except for the current you create) where streamlining has minimal effect. I've never read anything about anyone looking at this but it seems that one ought to be able to come up with some sort of interesting experiment.

And now we return to your regularly scheduled programming...

geochuck
January 21st, 2008, 10:11 PM
I have been tethered and have taken the tether to the limit. I have stayed 3 feet from the wall and it is very tireing for sure. Does it give you any advantage in a race I don't know but we are heading to Mexico for another 2 months in March. I will take a tether and take make videos to post.

knelson
January 22nd, 2008, 12:44 AM
The pitch of the hand is ineffective unless it's moving toward or away from the mid-line (sculling).

Huh? Please explain.

I understand what you're saying with the "quiet water" thing. When you start pulling, you accelerate the water behind your hand. To create additional propulsive force you need to find additional quiet water to accelerate. If you just continue to push on the already accelerated water you don't produce any additional force. However, your hand is already describing more or less an arc when viewed in a sagittal (i.e., "side") plane. So aren't we already getting that effect even without the "S" pull?

I just looked at Cecil Colwin's Breakthrough Swimming to see what he says about it. Not to say his view is definitive, but here's a quote:


Although the swimmer tries to pull in a direct backward plane, the rotation of the body on its long axis causes the hand and forearm to move laterally inward and outward under the torso. This action produces a natural sculling effect as the hand pitches inward across the body and then outward to round out the stroke at the side of the body...

LindsayNB
January 22nd, 2008, 09:21 AM
I understand what you're saying with the "quiet water" thing. When you start pulling, you accelerate the water behind your hand. To create additional propulsive force you need to find additional quiet water to accelerate. If you just continue to push on the already accelerated water you don't produce any additional force.

It has always seemed to me that many people in the swimming world use a rather simplistic if not misguided model of swimming physics. It seems like viscosity and drag are more appropriate tools for thinking about swimming than acceleration of mass. I think you will find that if you move your arm through water there will be plenty of force due to drag even after you have supposedly accelerated the water behind it. Another way to experiment with this is to put your arm in a horizontal position under the water and lift it up out of the water, observe how much of the water rolls off your arm instead of moving with it. Or stick you hand just under the surface and then throw some water up in the air, compare the force needed to accelerate the handful of water to the force needed to move your flat hand through the water at anything like an equivalent speed. I am open to being proven wrong but I don't think acceleration of mass is the dominant force to be thinking about, and certainly the idea that force goes to zero after you have accelerated the water behind your hand is just plain wrong and easy to disprove with a simple experiment.

geochuck
January 22nd, 2008, 10:34 AM
Do we have any quite water?

When the body moves through the water where does the water go. Some goes forward then it goes out, then it comes back and fills the void made by the body.

Once the shoulders pass through the water its starts roaring in to fill the void. We are not built like a boat pointed at the front end and wide at the middle and back end. The arms are our paddles and are not the pointed end of our vessel. Our width is from the head to the stomach where it is narrow again, wide again at the hips and then narrow at the back end. Then what some call the second wave really pours in to fill the void made at the middle and the back end. Now that water is moving towards the front. Now this is where the stroke starts to press on water going in the opposite direction. Firby always talked about this second wave with me we differred on what it was doing and how we could use it to our benifit. The so called second wave is the reason most sprint swimmers kick hard to use the second wave.

I think I like to use the water that is moving in the oppsite direction. This is why I mention the bow wave water. This is not the water that sets up that pretty "V" going out to the sides. I am talking about the water that is moving forward.

I don't need to listen to biomechanics. I can feel that water.

KaizenSwimmer
January 22nd, 2008, 11:08 AM
we know that swimming in turbulent water (i.e., another swimmer's wake) actually makes you swim faster

When we swim we create an area of higher pressure in front of the body and leave an area of lower pressure behind. The swimmer in a draft is getting to move through an area of lower pressure, reducing resistance.

When seeking purchase higher pressure is our friend. Thus the value of seeking quiet water. Introducing a slight S to our path is only one way. Small changes in hand pitch are another. A cleaner insertion and fewer bubbles is one of the most important.

LindsayNB
January 22nd, 2008, 11:18 AM
I don't need to listen to biomechanics. I can feel that water.

I would definitely trade my limited knowledge of hydrodynamics for better feel and kinesthetic awareness.

I only comment on physics when it seems to me that people are explaining swimming things using physics that seem to me not to be valid. I find the physics of swimming to be interesting but probably quite difficult to actually usefully apply to actually swimming.

knelson
January 22nd, 2008, 11:21 AM
It has always seemed to me that many people in the swimming world use a rather simplistic if not misguided model of swimming physics. It seems like viscosity and drag are more appropriate tools for thinking about swimming than acceleration of mass.

Still it all boils down to F = ma. If you aren't accelerating a mass, you aren't creating force.

geochuck
January 22nd, 2008, 11:44 AM
We can talk physics, hydrodynamics, insertion without bubbles, low pressure , highpressure, etc. But when it comes down to swimming you have to have a true feeling for the water. We are not a boat with one drive force. We have many moving parts and it still is going to be trial and error.

I once read an article about the dolphins and how their skin movement helped them swim. It talked about the ripple effect of the skin. This may be our next great breakthrough. I have read articles about shark skin and it's effects on movement through the water.

The US Navy and there new torpedos that will move through water at the speed of sound.

Still lots to come to make humans faster in the water.

LindsayNB
January 22nd, 2008, 11:44 AM
Still it all boils down to F = ma. If you aren't accelerating a mass, you aren't creating force.

Not all forces are the result of the acceleration of a mass. I think you are overlooking viscosity.

If you are pushing, the water is pushing back with an exact equal force.

Even working just with F=ma, any water you have accelerated is in turn running into further water that has not yet been accelerated.

As I said, drag your arm through the water at a constant speed, this will require force even if your arm is not accelerating.

geochuck
January 22nd, 2008, 11:53 AM
As the Jedis say "May the force be with you."

knelson
January 22nd, 2008, 11:58 AM
As I said, drag your arm through the water at a constant speed, this will require force even if your arm is not accelerating.

Yes, because you are accelerating the water surrounding your arm due to the viscous shear. I still think it's F=ma whether we're talking about viscosity or not.

Kevin in MD
January 22nd, 2008, 12:44 PM
We can talk physics, hydrodynamics, insertion without bubbles, low pressure , highpressure, etc. But when it comes down to swimming you have to have a true feeling for the water. We are not a boat with one drive force. We have many moving parts and it still is going to be trial and error.


We are definitely in a situation where fluid mechanics has not caught up with human propulsion in the water. I think coaches throwing around half-cocked theories of propulsion tends to slow down the effort to explain what is going on. In all the hoorah about lift forces for propulsion I saw exactly one study with numbers on it referenced. For shed vortices, none.

Ernie Maglischo in swimming fastest references some computational fluid dynamics studies showing that a slight side to side motion creates more propulsion, but not because of lift, it actually improves the drag forces on the hand as you pull.

If we are to get anywhere, for now it looks like the computational fluid dynamics will help us. But these things are fiendishly difficult to solve and take real horsepower. The ones listed here (http://projects.seas.gwu.edu/~fsagmae/Swim%20Pages/MAIN.htm) take 20 days or so to solve.

So I think we are left trying to feel the water and get a better purchase on it, we are also left having to discuss with no real science to back us up.

quicksilver
January 22nd, 2008, 01:43 PM
In simple terms..you can't really apply physics on land towards hydro-dynamics.
I agree about mass and acceleration providing greater force...but the force has to applied effectively towards the water...not slipping through it.

Example...A Mississippi paddle boat with enormous horsepower moves huge volumes of water and goes nowhere fast.
Take the same vessel...replace the paddles with propellers...and it's a different story.


Sculling the hand provides the same effect as does a propeller.
It's the difference between slipping and gripping.

Rob Copeland
January 22nd, 2008, 02:19 PM
In other simple terms..you can't really apply hydro-dynamics of rigid structures to those of human motion.

Example 2 – Take that Mississippi paddle boat, extend the paddle 1/3 again in front of the boat, teach it proper EVP (Early Vertical Paddle) and have it pull/push the paddle past amidships ...and it's a different story.

Sculling the hand at 14,000 RPM provides the same effect as does a propeller, but it may cause other problems.

knelson
January 22nd, 2008, 02:40 PM
Yeah, that's the other problem. As if the aerodynamics (or hydrodynamics, if you insist) were not difficult enought to get a grasp on, human physiology has to rear it's ugly head. There's a constant tradeoff between the ideal stroke from an aerodynamic standpoint and the ideal stroke from a biomechanical standpoint.

geochuck
January 22nd, 2008, 02:49 PM
Bubbles around the body is what we need so we can travel faster through the water. This is a picture of a body moving at 3 times the speed of sound underwater. Bring on the bibbles.

Iwannafly
January 22nd, 2008, 02:54 PM
The US Navy and there new torpedos that will move through water at the speed of sound.



There are absolutely no such things as torpedoes that move through the water at the speed of sound. The speed of sound in air is ~770 miles per hour (or 344 m/s) (depending upon relative humidity and temperature) and significantly faster in water. Russia developed a supercavitation torpedo (http://www.military.com/soldiertech/0,14632,Soldiertech_060420_shkval,,00.html) in the 70s that reached speeds of approximately 300 knots (or ~340 mph). That's only about one tenth the speed of sound in seawater. The picture in geochuck's post is of this Russian "Shkval Rocket Torpedo" and there are several websites that dispell the myth that these weapons approach the speed of sound.

This discussion is very fun for someone of my limited intellectual capacity, but limitless affection for physics and mathematics (read, I am a geek, just ask my wife)!
Any discussion of peak athletic performance in water has to involve both human kinematics and hydrodynamics. The hydrodynamics portion of the equation is far too complex to solve by hand and must be estimated by computational fluid dynamics (CFD).
So, a fluid mechanics person could probably develop a model of the ideal swimmer, but it's another matter entirely to assume that each swimmer can manipulate and/or coordinate their body to fit the model. The bottom line is that the swimmer must minimize drag along his/her body, but maximize drag on the pulling surfaces (forearms and hands).
I've only been swimming for about a year now, so I won't claim to be anywhere near an expert about stroke mechanics, so I won't begin to claim I know how to maximize drag on my hands and forearms while minimizing the drag along my body. I do know that each time my coach makes a change in my stroke, I can feel the difference!
I don't know if I contributed anything to the post, but I certainly do like to hear myself talk:)!

geochuck
January 22nd, 2008, 03:00 PM
Oh contrair the Iranians have and the Russians do have such an item. The Russians are supplying the Chinese subs with a torpedo which travels near the speed of sound. http://www.military.com/soldiertech/0,14632,Soldiertech_060420_shkval,,00.html

Here is an article about dolphins http://www.physorg.com/news68812337.html

knelson
January 22nd, 2008, 03:01 PM
The speed of sound in air is ~770 miles per hour (or 344 m/s) (depending upon relative humidity and temperature) and significantly faster in water.

Yeah, about 1,500 m/s at standard temp and pressure. That would be one fast torpedo!

Here's an article about the supercavitating torpedoes: http://www.popsci.com/popsci/technology/generaltechnology/de669aa138b84010vgnvcm1000004eecbccdrcrd.html

I don't think the torpedoes are quite that fast, but it does mention the Navy have successfully launched a supercavitating projective that surpassed the speed of sound underwater. Pretty amazing!

Iwannafly
January 22nd, 2008, 03:14 PM
It is a myth that the Shkval travels faster than the speed of sound. It exceeds 200 mph, but gets nowhere near 700 mph. The Popular Science article only says that the US Navy has tested a prototype, but it never says that prototype approached the speed of sound. Geochuck, the military.com article you linked to dispels the myth that this weapon approaches the speed of sound!

LindsayNB
January 22nd, 2008, 03:16 PM
Kirk, perhaps I am using viscosity incorrectly, the proper term might just be drag.

The problem I have with F = ma is that both the m and the a involved are horrendously complex, unlike with solids. Water is being accelerated backwards, and upwards and in all sorts of directions around the arm and the acceleration is highly variable between bits of the total mass. If you can't nail down the mass involved, or the acceleration involved, how useful is the equation?

Drag on the other hand is a simpler concept to deal with, it is just the force necessary to drive the arm through the water at a given speed, including all factors. You can predict that an arm moved through water that is already flowing in the same direction will have reduced drag and transfer less force.

Sorry for belaboring the point. :duel:

Kevin, those animations are very cool, even if I can't grasp what information they convey!

quicksilver
January 22nd, 2008, 03:19 PM
Sculling the hand at 14,000 RPM provides the same effect as does a propeller, but it may cause other problems.

Yes, like maybe some serious carpal tunnel syndrome. :D

geochuck
January 22nd, 2008, 03:38 PM
It is a myth that the Shkval travels faster than the speed of sound. It exceeds 200 mph, but gets nowhere near 700 mph. The Popular Science article only says that the US Navy has tested a prototype, but it never says that prototype approached the speed of sound. Geochuck, the military.com article you linked to dispels the myth that this weapon approaches the speed of sound! Yes the Shkval is a very slow 253 mph underwater. Irans torpedo maybe a fabriction??? Do you really think this.

The word is there have been US tests at near the 770mph but this could also be a fabrication.

Is it revelant to how fast we swim. NO

I don't shave my body and I can see little bubbles all over my body where hair is growing when I take underwater pictures. Do you think these bubbles are similar to the bubbles made by these newer type torpedos.

Iwannafly
January 22nd, 2008, 04:04 PM
Yes the Shkval is a very slow 253 mph underwater. Irans torpedo maybe a fabriction??? Do you really think this.


The Iranians are buying Shkvals from the Russians including the submarines that are deploying them. They have not developed their own supercavitating weapon. The only information I've heard about US supercavitating torpedoes is that we have tested some prototypes, but they are nowhere near as fast as the speed of sound in air, let alone water.

You're right, this has no bearing on our ability to swim. Perhaps if we could expel enough air to envelope our body, we could reduce drag significantly. Hmmmm, sounds like hypoxic work to me!:D

I couldn't resist the urge to reference another controversial topic.

Noodles Romanoff
January 22nd, 2008, 04:05 PM
The word is there have been US tests at near the 770mph but this could also be a fabrication.And the WORD is also that the technology used to build these super sonic Thorpedos was stolen from aliens that crash landed in the 50’s in New Mexico.:shakeshead:



Do you think these bubbles are similar to the bubbles made my these newer type torpedos.NO.:doh:

geochuck
January 22nd, 2008, 05:25 PM
Sound of speed in Water is something like 3000 Mph or is it 3000 knots per HR??
In fresh water, sound waves travel at 1482 meters per second (about 3315 mph). ... The exact speed of sound in steel is 5960 meters per second (13332 mph)

tomtopo
January 22nd, 2008, 05:33 PM
Iwanafly said it very well - “The bottom line is that the swimmer must minimize drag along his/her body, but maximize drag on the pulling surfaces (forearms and hands).” A definition of eddie current is ; “a current, as of water or air, moving in a direction that is different from that of the main current. Eddies generally involve circular motion; unstable patterns of eddies are often called turbulence.” The turbulence created as a swimmer moves forward and surrounds the body is an eddy current, the turbulence behind the hand is called a vortex which creates a drag force not conducive to propulsion. It’s also important for swimmers to clean/clear their hand of air because it also decreases drag or the ability of a swimmer to hold or leverage water effectively.

In order to maximize drag, like Iwanafly says, your hand must stay away from turbulent water. It’s not a freakish or weird theory. Ernest W. Maglischo, spends three pages on the Vortex theory. In the first chapter “Increasing Propulsion” from his book “Swimming Fastest – The Essential reference on technique, training, and program design” Ernie devotes over 40 pages on this fascinating topic (propulsion). Dr. James Councilman’s and his timeless book “The Science of Swimming” also spends a lot of time helping swimmers and coaches understand the importance of fluid dynamics and how it relates to competitive swimmers. If swimmers and coaches would read these two books the complex world of fluid dynamics becomes more clear. It is indeed complicated but not incomprehensible, even to guys like me.

As swimmers we would all like to become more efficient and faster. All coaches should have a solid understanding of stroke mechanics and how physics plays a role in swimming faster. Teaching swimmers how to reduce resistive forces by streamlining the best they can, and getting them increase propulsion by pulling and kicking with the best possible technique should be the mission of every swim coach.

So, how you pull your hand and position it as it travels through the water is important for fast swimming. Don’t over-exaggerate the “S” pattern, avoid stopping the propulsive mechanisms by gliding, clear the hand of air as you enter it into the water, set-up your forearm and get it vertical early, find a pulling pattern that is the most effective for you (improve your DPS), improve ankle flexibility and core strength, and train smarter not just harder. Good luck, Coach T.

Rob Copeland
January 22nd, 2008, 05:50 PM
Sound of speed in Water is something like 3000 Mph or is it 3000 knots per HR??Knots notes: Knot is already a unit of speed (equal to one nautical mile per hour)
And if you want to calculate the speed of sound in water just follow the simple empirical equation below for the speed of sound in sea water:

c(T, S, z) = a1 + a2T + a3T2 + a4T3 + a5(S - 35) + a6z + a7z2 + a8T(S - 35) + a9Tz3
where T= temperature in degrees Celsius, S = salinity in parts per thousand and z = depth in meters, respectively.
The constants a1, a2, ..., a9 are: a1 = 1448.96, a2 = 4.591, a3 = -5.304×10-2, a4 = 2.374×10-4, a5 = 1.340, a6 = 1.630×10-2, a7 = 1.675×10-7, a8 = -1.025×10-2, a9 = -7.139×10-13

But back on topic… good observations Coach T.

tomtopo
January 22nd, 2008, 08:08 PM
How about a sailing invite so you two could teach me more about what you're talking about????

geochuck
January 22nd, 2008, 08:27 PM
Tom - sound travels faster underwater depends on temperature of the water and whether it is fresh or salt water.
Make a noise underwater it travels at over 3000 mph.

Above water on land sound travels at 770 mph.

Really it has nothing to do with swimming unless your coach is yelling at you.

david.margrave
January 22nd, 2008, 09:31 PM
I was at a Masters clinic yesterday at the University of Washington. One of the coaches (Thomas Hannan) said that the S-shaped stroke still occurs when you look at your hand position relative to your torso, when you take body rotation into account, which is similar to the quote that Kirk referenced.

geochuck
January 22nd, 2008, 10:12 PM
Right - the "S" Stroke is still there but is hidden by the fact that most swimmers of to day are rotating the shoulders and it no longer looks like an "S" Stroke. Now does this fool us into believing we are doing an "I" Stroke??? I happened to see George Breen doing the big cross over stroke that Coucilman called an "S" stroke and was it ever a cross over with George Breen's almost scissor kick.

craiglll@yahoo.com
January 23rd, 2008, 11:11 AM
Right - the "S" Stroke is still there but is hidden by the fact that most swimmers of to day are rotating the shoulders and it no longer looks like an "S" Stroke. Now does this fool us into believing we are doing an "I" Stroke??? I happened to see George Breen doing the big cross over stroke that Coucilman called an "S" stroke and was it ever a cross over with George Breen's almost scissor kick.

I was told once that we are really planting our hand in water then vaulting our bodies over our planted hand. Sometimes this image works, sometimes it doesn't. The coach who told me this said that simple human body shape will force you to do a S movement with your stroke.

cantwait4bike
January 23rd, 2008, 12:48 PM
just to simplify this thread (nuke out the iran stuff), how close to the body mid-line should the hand come when directly under the chest?? on the mid-line, 2-4 inches off, 4-6?, 6-8, 8+ ?

geochuck
January 23rd, 2008, 01:36 PM
This is for you to personally find out. What feels good for me may not feel right for you. It does all of those measurements during a stroke. Try them all and find what you like. Maybe some one can give you exact measurements I can't but your muscle and body frame will make the difference. It is a trial and error process. It is not a one size fit all process.

mermaid
January 23rd, 2008, 03:22 PM
This is for you to personally find out. What feels good for me may not feel right for you. It does all of those measurements during a stroke. Try them all and find what you like. Maybe some one can give you exact measurements I can't but your muscle and body frame will make the difference. It is a trial and error process. It is not a one size fit all process.

Ditto from me.

geochuck
January 23rd, 2008, 05:16 PM
Here is a little more about Fluid Mechanics. http://www.pantherhouse.com/newshelton/fluid-mechanics-and-transport/

I mentioned George Breen a couple of posts ago here is his 1500m at the 1956 Olympics http://www.ishof.org/video_archive/swimming/1956_1500m.htm


We are definitely in a situation where fluid mechanics has not caught up with human propulsion in the water. I think coaches throwing around half-cocked theories of propulsion tends to slow down the effort to explain what is going on. In all the hoorah about lift forces for propulsion I saw exactly one study with numbers on it referenced. For shed vortices, none.

Ernie Maglischo in swimming fastest references some computational fluid dynamics studies showing that a slight side to side motion creates more propulsion, but not because of lift, it actually improves the drag forces on the hand as you pull.

If we are to get anywhere, for now it looks like the computational fluid dynamics will help us. But these things are fiendishly difficult to solve and take real horsepower. The ones listed here (http://projects.seas.gwu.edu/~fsagmae/Swim%20Pages/MAIN.htm) take 20 days or so to solve.

So I think we are left trying to feel the water and get a better purchase on it, we are also left having to discuss with no real science to back us up.

cantwait4bike
January 23rd, 2008, 08:41 PM
This is for you to personally find out. What feels good for me may not feel right for you. It does all of those measurements during a stroke. Try them all and find what you like. Maybe some one can give you exact measurements I can't but your muscle and body frame will make the difference. It is a trial and error process. It is not a one size fit all process.

oh common on all you swimmers, how about i make easy for you: at the mid-line, 2 feet out, or 2 feet the other side of the mid-line. this is a TEST.

geochuck
January 24th, 2008, 09:58 AM
I will certainly give it a try and test your theory out but I don't think that is a great option. I will let you know.

oh common on all you swimmers, how about i make easy for you: at the mid-line, 2 feet out, or 2 feet the other side of the mid-line. this is a TEST.

knelson
January 24th, 2008, 10:58 AM
Here is a little more about Fluid Mechanics. http://www.pantherhouse.com/newshelton/fluid-mechanics-and-transport/

I'm not sure what your link is, George, but I got a "denied access due to adult content" warning when I just tried to open it at work.

geochuck
January 24th, 2008, 11:10 AM
Nothing like you are imagining it is clean not for adults only. It is messy, about humans swimming in an almost solid fluid.

david.margrave
January 25th, 2008, 03:18 AM
here's another copy of the story

http://www.it.umn.edu/news/inventing/2004_Winter/goingforthegoo.html

LindsayNB
January 25th, 2008, 10:58 AM
I've been sick the last few days and am probably not thinking straight, but, it seems to me that this experiment says something about mass versus viscosity. The article says the viscosity was doubled, if we presume that the mass of the guar gum was a small fraction of the mass of the water in the pool (or at least that the mass of the mix was much less than double the mass of water) then we should be able to predict differences in the effect if swimming is viscosity based or mass based. If mass was the dominant factor then the swimmers should have slowed down considerably as the drag of moving through the thicker, more viscous fluid is doubled while the mass that is being accelerated backward is increased by a much smaller amount. If viscosity was the dominant factor then the increased resistance to forward movement would be balanced by an equal resistance to the backward movement of the propelling limbs. The experimental results were the latter.

In reality when a body moves through a more viscous fluid a larger volume, and hence larger mass, is dragged along, so it is really two sides of the same coin, but even so, this extra step in providing an explanation seems to me to unnecessarily complicate the explanation versus just directly talking about drag, and it doesn't correspond to the intuitive model of pushing mass backward. Yes, yes, very pedantic. Sorry. :o

geochuck
January 25th, 2008, 11:06 AM
It surelly is a messy subject. Lindsay are you being too practical? I think if we were to exagerrate the "S" it would change the results???

LindsayNB
January 25th, 2008, 11:15 AM
It surelly is a messy subject. Lindsay are you being too practical? I think if we were to exagerrate the "S" it would change the results???

Actually, I'm not sure I'm being practical at all!

It would have been interesting to have observed the effect on a high-glide breaststroke (200m style) or a catchup freestyle versus a more continuous propulsion style.

geochuck
January 27th, 2008, 12:27 PM
Here is a video on hydrodynamics.
http://video.google.ca/videoplay?docid=1817680875502850175

LindsayNB
January 27th, 2008, 02:31 PM
Very cool George, the day when this stuff becomes useful for swimming analysis may not be that far away! The ability to put markers in the water to make the flow more visible is especially interesting and could produce interesting visualizations even just using rigid models of swimmers or their body parts.

Check this one out:
http://www.youtube.com/watch?v=K5Lejtf1abM
So non-rigid objects are also possible.

I wonder if how expensive and hard to learn the software is.

This video is also kind of cool:
http://www.youtube.com/watch?v=b7MXX4LkKHQ

The future is going to be so cool...

zwrdl
March 26th, 2009, 11:40 PM
Don’t over-exaggerate the “S” pattern, avoid stopping the propulsive mechanisms by gliding, clear the hand of air as you enter it into the water, set-up your forearm and get it vertical early, find a pulling pattern that is the most effective for you (improve your DPS), improve ankle flexibility and core strength, and train smarter not just harder.

Thank you very much.

I am self taught and have been following Councilman's and Maglischo's theories and details of stoke mechanics for several decades. I know that swimmers need to swim by feel, but it would be useful to have the most current book on freestyle stroke mechanics to build from.

Reviews of Maglischo imply that even his Swim Fastest is dated.

Is there any book or combinatins of books that you might recommend to bring my stroke into the 21st century?

I'm an open water swimmer, and my most prized goal is maximum efficiency for an hour and a half of sustained freestyle. I can do the hour and a half, but I'm using out of date mechanics. And my joints are getting old.

Thanks very much.

mccalack
May 1st, 2012, 04:43 PM
I have used the S-Stroke for years and feel it gives me a lot of thrust per stroke. My right hand enters the water, with my arm fully extended, to the left of my head, and with the handed cupped, I make a more or less S, or maybe a sweeping motion below my left sholder down to left hip and then crosses over and exit water above my right knee. No-one showed me this, it is just what developed from trying different styles.