Gerko - Rs - Presentation(r1)

7/27/2019 Gerko - Rs - Presentation(r1)

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There are many factors which influence and determine a sprint or

marathon paddler's overall performance.

Not all the determinants of performance are equally significant.

The major factors influencing the racing canoeist's performance are

summarised diagrammatically below:


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Kayak Blade Tip Pattern in the

Water during a Stroke


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The Differences Between Traditional Asymmetrical

Blade and Wing Blade Propulsion Forces


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-The canoeing technique utilises the principleof the lever in two ways.

-The force applied to the shaft by the upper

(pushing) hand is on the opposite side of thefulcrum (lower hand) to the load which is

centred on the blade.


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This is an example of a first-class lever.

The other example of the principle of

leverage is the third-class lever which placesthe force (lower hand) between the fulcrum

(upper hand) and the load (blade).


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According to most authorities, the first-class

lever is emphasised more in the first part of

the stroke and the third- class lever in thesecond part, once the shaft has become

vertical.

A first-class lever is the most efficient from a

maximum force point of view and thesecond-class lever more efficient from a

speed point of view.

This helps explain why the first part of thestroke is the stronger, whilst the second part

is weaker, but faster moving.


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The Entry Phase

(i) View from Above

(ii) View from Front


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Common faults:

Pulling past the hip - a slow exit causing the

boat speed to move the paddle forward

relative to the water. (If

paddle exit during feathering is done too

slowly, an unwanted drag results).


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View from above View from

side


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Coaching Tips:

Care should be taken to ensure that therotation of the shaft takes place while

the paddle is completely free of thewater.

Rotating the shaft while the control handblade remains in the water causes a

difficult exit and not completing rotationprior to the next stroke causes a catchwith the blade not square to the water.


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If you get too far forward you will be disadvantaged because you

will in effect be paddling uphill (up the leading boat's bow wave)

and similarly if you are too far back you will be doing the same

thing but paddling up the leading

boat's stern wave.


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Although it is possible to ride the wave

behind a canoe, there is less support in thisposition. The most efficient"ride" is behinda canoe with two others wash hanging oneither side of the leading craft.


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If you do drop back, there are two ways of catching up.One method is to approach the leading craft from behind.

Paddle hard as you go up and over a wave, then

recuperate temporarily by taking advantage of the smallstern wave before sprinting to get up and over the nextone.

The view from above would look like this.


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The most recent innovation in paddle design is the "wingpaddle", pioneered initially in Sweden.

This blade has a curled upper edge to reduce slippage andat the same time generate drag by creating a low pressurearea in

front of the paddle.

By forcing the paddle blade out sideways as the boatmoves forward, the paddle is able to make better use of thelarge muscles of the back and torso.


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Biomechanics of Swimming

Introduction

Training is the way to improve the technique and

coordination, strength and aerobic capacity.

Competitive swimming has many action like

breaststroke, backstroke, butterfly, front crawl ordistance swum (50 m - 1500 m).

But, a 50 m sprint uses 23 s require for

instance considerable strength, power and

technique.The 1500 m takes at least 14 min 40 s to

complete.

Different types of swimming have different drag.


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Drag

1. Frictiondrag

2. Pressuredrag

3. Wave drag


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3 ways for drag

1.Friction drag

Definition: the part of the drag on a body movingthrough a fluid that is dependent on the nature of

the surface of the body. Also called skin friction.

It is between different layers of water as they move

past one another.


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2. Pressure drag

Definition: the part of the

total drag of a body

moving through a gas orliquid caused by the

components of the

pressures at right angles to

the surface of the body.

The swimmers body may

separate and depend on

the shape, size andvelocity.


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More streamlined

swimmer

Swimmer producing

more drag


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3. Wave drag

When swimming near the surface, water tends

to pile up in front of the swimmer and to form

hollows behind, thus creating a wave system.


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Measurement of drag


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Factors determining active drag


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Propulsion in Human Swimming

a-b: entry

b-c: entry scull

c-d: inward pull

d-e: outward pull

e-f: exit


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http://www.mira.co.uk/Services/images/bike.jpg


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Introduction

Aerodynamics, or wind resistance is an

everyday experience to bicyclists. At

average speeds aerodynamic drag is

the largest resistive force aside from thegravity of a large hill

Due to the fluidity of air.

Composed of normal (Pressure) force and

tangential (frictional) force.

Extremely geometry dependent.


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Fl id M h i &


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Fluid Mechanics &

DynamicsAir as a fluid

When studying aerodynamics air is treated

as a fluid.

Follows all laws of motion and all laws offluid mechanics

http://pico1.e.ft.fontys.nl/aot/newton.jpg

F = mConservation of Energy

Conservation of Mass


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Aerodynamics

Two effective forces Pressure

Friction

For cyclists, pressureeffect is much largerthan friction due to non-streamlined body.

Streamlined bodiesincorporate gradualtapering to minimizepressure effect andseparation of fluid

(a) Normal pressure and friction forces (b) Attached andseparated flow around a cylinder (c) Attached flow andpressure recovery along a streamlined body

Figure from Bicycle Science pg. 174


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Aerodynamics Laminar Flow

Layers of fluid flow slide smoothly over one another

Turbulent Flow Boundary layer is composed of vortices that increase

surface friction.

Common at rear end of non-streamlined vehicle

Turbulent Laminar

http://www.cheng.cam.ac.uk/research/groups/electrochem/JAVA/electrochemistry/ELEC/l2fig/laminar.gif


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Bicycle Aerodynamics

Bicycle is responsible for 20-35% ofdrag.

Loose Clothing increases drag by up to

30%.


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Bicycle Aerodynamics

Fairings

Reduce Drag Coefficient up to 50 %

https://reader008.{domain}/reader008/html5/0416/5ad43e440cf33/5ad43e62d9881.jpg Image from Bicyc


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Bicycle Aerodynamics - Drafting

Drafting

http://pro.corbis.com/images/AX933548.jpg?size=67&uid={51D3B79C-B5D0-4A72-B318-B002D5C78EBC}

Traveling close behindanother rider

Broken up air vorticespropel second rider

Offers advantage toboth front and rear

rider Riders in group

expend 40% lessenergy than solo

riders


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References

http://canoesouth.org/uploads/The%20Science%2

0of%20Canoeing(1).pdf

R. W. Cox 1992 Published by Coxburn Press, 13

Bradley Lane, Frodsham, Cheshire WA6 6QAR.
http://canoesouth.org/uploads/The%20Science%20of%20Canoeing(1).pdfhttp://canoesouth.org/uploads/The%20Science%20of%20Canoeing(1).pdfhttp://canoesouth.org/uploads/The%20Science%20of%20Canoeing(1).pdfhttp://canoesouth.org/uploads/The%20Science%20of%20Canoeing(1).pdf

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Gerko - Rs - Presentation(r1)