Sculling traction

[Zenturtle]

here is some elite doing a 6 stroke 25 m.
He uses a big scull in his pull to get extra traction.
Hand basically does not move back while body glides forward during his scull.
At higher strokerates there is no time for these tricks and wiggling the arm around much.
When doing doggy paddle the urge to scull becomes greatest i think. You almost start to wiggle your hand automatically under the body then.

scull start point


scull inward

[Zenturtle]

scull outward
image uploaden

finish
upload photo

so his hand leaves at the same place where it started the scull at the red line, while his head moved from 2.5 tiles to 4.5 tiles, so 2 tiles forward.

from this video>
https://www.youtube.com/watch?v=Lao-GJ74jkU

[Zenturtle]

So, whats his slippfactor then?

6stroke 1


6 stroke 2


6 stroke 3


his hand moves 2.4 tiles back, while his head moves 3 tiles forward.Slipfactor = 2.4/3= 0.8. So not super for an elite, but very good taking the 6 stroke in account.
There has to be relative much deceleration between strokes, so at every stroke he also has to accelerate his body again, which takes extra force = extra slippage.

Sclim, there is 1 component I forgot: the kick propulsion. More kickpropulsion at the back, means less propulsion at the front, means less slip.
This guy has opened my eyes for the possible propulsion of the legs , even from a 2 BK. Never thought you could get so much propulsion from a 2BK.
Still hate the kneebend it needs to set the big kick up, making it a nono for higher speeds I think. Have to take a look how much Sun Yang bends his knee.

[Zenturtle]

If we compare the elite guys with an adult onset swimmer, we can see the ellite are doing pretty well, and the adult onset swimmer has some work to do to keep up technically.
Coach Stuart also has a slipfactor of about 2 for example.
stuart 1


stuart 2


stuart 3


from this footage
https://www.youtube.com/watch?v=mAFli6CVFCg

if anybody can supply some info about the last swimmer, Rachel Vanscoy...I love here stroke.. very nice.

[WFEGb]

Hello ZT,

Terry's SF has been around 0.79 with 1.02-SR (I'd call that competition SR). Interesting for me the SF in his first phase from just starting the hand's hook to nearly vertical is 0.8 and the second part 0.78, just oppsosite to Shinji's.

Best regards,
Werner

[Zenturtle]

So, we now have another abbreviation in the swimming jargon: SF :-) ?

Again, you didnt pick the right start point. The start point is not where the hand is still gliding forward, but the point where it starts pressing water back. Thats where the slipping starts.
The slipfactor is only about the backward pressing phase of the underwater armstroke. It gives an indication how much hold you have on the water. How much the arm is slipping.
If you pick a point where the arm is still moving forward you get a much lower slipping factor, because then you add up negative slip (hand moving forward in the water) and positive slip (hand moving backwards in the water).
With a stationairy background you can determine pretty precise when the hand starts to move backwards.

But, its fun that someone else is also interested in this stuff.