Re: Brooke Bennet-A weak kicker?

I had seen those videos. They are half speed videos, and she is doing
cross over kicks as a race strategy. I had seen her swim in person.
If a video is needed as a proof, I had one :-). She can kick pretty
well.

I have seen on TV (unfortunately just once) Claudia Poll in one of the
200m free semifinals at Athens. By contrast with the clips at the
Graft's site, there were shoots from above water. The one thing that
impressed me, was the really big wave formed at the Poll's feet. I
don't mean the roaster tail, but the wave itself, and she was using her
two beat kick. That couldn't be a weak kick at all. I don't know if
there is a clip from that race anywhere in the web. If anybody knows
that please tell me.

I wonder if the height of the rear wave could be used to measure how
much propulsive is the kick.

(Sorry for my English)

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Quoted message said:

I have seen on TV (unfortunately just once) Claudia Poll in one of the
200m free semifinals at Athens. By contrast with the clips at the
Graft's site, there were shoots from above water. The one thing that
impressed me, was the really big wave formed at the Poll's feet. I
don't mean the roaster tail, but the wave itself, and she was using her
two beat kick. That couldn't be a weak kick at all. I don't know if
there is a clip from that race anywhere in the web. If anybody knows
that please tell me.

I wonder if the height of the rear wave could be used to measure how
much propulsive is the kick.

The answer is in all probability no.

This "rear wave" is part of a wake produced by the body's passsage through
the water.

Humans travel in water at speeds such that their bodies should be considered
displacement hulls (anyone who claims that swimmers can "plane" doesn't know
what they are talking about). For displacement hulls, the fastest they can
travel is shown when there is a single pair of waves, one at the bow and one
at the stern.

Good swimmers can achieve this; the bow wave is no trouble, but making the
single stern wave means that they must have good form and a (relatively)
steady speed. The position of the stern wave will vary - for very good
swimmers it will be near or at the feet - for poorer swimmers it may be
part-way up the calf, or even at the knee. Swimmers who show a wave at the
mid-thigh or hips will most likely not have a 2-wave wake but a 3-wave one,
and so are not travelling at hull speed.

The length of the wave produced is related to the speed of travel - longer
means faster. The height of the wave is related to the amount of water
disturbed by the passage - less height means less disturbance.

A body with a smaller displacement, for a given waterline length, will
produce a lesser disturbance of the water, and require less power to do so.
This of course is influenced by the actual shape of the hull; often in the
case of swimmers not so much by static shape as by the dynamic
configuration - position of arms and legs and flexure of the trunk and so
on.

So the goal of a swimmer in regard to wake formation is to swim with as
large a distance between bow and stern waves as possible, with both waves
being as low a height as possible.

In your observation of Miss Poll's performance, it is unlikely that any
conclusion could be drawn about any propulsive effect her kicking may have
had, from the height of the stern wave; less likely than any conclusion
about her use of Norandrosterone could be drawn from the same observation.

jtaylor said:

The length of the wave produced is
related to the speed of travel -
longer means faster. The height of
the wave is related to the amount of
water disturbed by the passage - less
height means less disturbance.

Great post. Here's an illustration of the two and three wave effects:

http://www.donalfagan.com/html/firby.html