Friday, February 09, 2007

Kayak paddle fitting

Here is an article I posted recently on surfski.info on kayak paddle fitting based on an accumulation of flatwater and surfski coaching, listening to others and my own experience. I've added and clarified certain areas based on follow-up discussions.

Here are some quick guidelines to consider in setting your paddle up;

1. Twist: left or right? There is little you can do with his parameter as you will be either one of the other. It is rare to find an ambidextrous kayaker re twist. In an ideal world you can choose which one is best for you, in the real world those who don't have access to a two piece paddle are stuck with what is available where and when you learn.

Some coaches say twist is often associated with handedness (i.e. right handed people are often right twist), but not always. It is however a good starting point.

A quick and easy way to tell is do some "air paddling" while standing and have someone watch if the paddle orients itself correctly on "entry". If you end up slicing (where the paddle would enter parallel to the side of the kayak) you need the opposite twist.

An empirical way to know which twist is right for you is see if you always fall in over and over again at the entry/catch on the same side. If the blade slices in every time on a given side it is probably a twist issue. Always falling in at the exit on the same side is probably more of an exit mechanics / twist angle problem, but in some cases it may be a left-right twist issue.

Twist is very tricky for many paddlers and they resort to getting "twist" by flexing the wrists.

For those with ovalized paddle shafts (either designed oval like Epics or with finger key on grip side) try to change the paddle angle by rolling the paddle shaft along your grip side fingers as they flex/extend and NOT by flexing the wrist. It is important to have finger guides (see point #6 below) on the paddle when keeping a looser grip to ensure you are gripping in the correct orientation. This technique also relaxes your grip.

It takes practice but can greatly minimize the risk of wrist overuse injuries.

Practice using a light weight wooden dowel or broom handle, and a light paddle helps greatly in using this in real life. Your fingers will get sore for a while as they strengthen, but they will adapt quickly.

2.
Twist angle: Determining the twist angle on a wing blade will have a drastic effect on your stroke. This is the angle between the two blades of the paddle running down the long axis of the paddle shaft. Normally a twist of zero (0º) mean there is no difference while 90º indicates the blades are perpendicular to each other.

Newer paddlers are best with a fairly flat angle, say 60º a this allows easy entries with minimal need for a steep angle on entry (which may compromise balance) and an easy exit that will lift/catch minimal water. With a wing blade, a steeper angle will require better exit mechanics. If the angle is too steep for your exit skill, the blade will often pull under the hull, or grab on the exit leading to a swim or very poor balance as you will pull your exit side shoulder down towards the exit every time you lift it out, which will affect the entry on the opposite side, and so on in a nasty catch-22 scenario.

As paddlers become more skilled the angle can be changes to accommodate progressing skill and water conditions. If you have a very good exit and the water is flat (re your perception) you may select a steeper angle (toward 70-80º). However, exit mechanics need to be very good or you will pull yourself off balance when you try to extract the blade or you pull back too far.

For very rough water when you know you’ll be paddling flatter (left-right angle) to keep you center of gravity low, flatten out the angle on the blade back toward 60º.

3. Length: this is often determined as a function of sitting height over the water in the kayak, length of the event and paddling style.

A good starting point (that assumes a relationship between limb length and torso length) is to sit holding a paddle or a broom handle, etc. with your upper arms parallel to the ground and your elbows bent at 90º with your hands up (i.e. perpendicular to the ground). Grip the shaft so that your thumbs are on the inside of the grip. Have someone measure the distance between your thumbs. For flatwater kayaking this distance equals ~1/3 of your overall paddle length, the middle third. The other two thirds are located from each thumb to the tip of the paddle.

For beginner flatwater paddlers shorten this distance slightly (up to 5 cm). New paddlers tend to paddle with a flatter stroke (left-right angle) and have poorer posture (i.e. they are shorter in the kayak).

For beginner surfski paddlers shorten this distance (up to 15 cm). New paddlers tend to paddle with a flatter stroke (left-right angle) re flatwater paddlers and slouch more in the ski.

For more advanced surfski paddlers shorten this distance (0-15 cm). Non-flatwater trained surfski paddlers tend to paddle with a slightly flatter stroke (left-right angle) re flatwater paddlers and very skilled ski paddlers will sit up taller in the ski if conditions allow.

In rough and sloppy water shorten the paddle slightly (0.5-2 cm). This allows a slightly faster stroke rate for the same hull speed (i.e. less force per stroke) which improves balance in most paddlers.

In very long events where cadence may drop from fatigue you can shorten the paddle slightly (0.5-2 cm). This allows you to maintain a slightly faster stroke rate for the same hull speed (i.e. less force per stroke) which holds off fatigue a little longer in most paddlers.

In flat glassy calm water lengthen the paddle slightly (0.5-1+ cm). This allows the paddler to slow the stroke rate slightly by stabilize the paddle relative to the kayak more and increasing the force per stroke without compromising balance too much.

If you grip too narrow on your paddle shaft you use a lot of bicep and chest strength (smaller muscles). A wider grip will allow you to use more torso and back strength (bigger muscles). For each person there will be a happy medium based on your biomechanics.

Too short and paddlers slouch, pull with the arms and have poorer technique.

Too long and paddlers have trouble with balance at the entry and exit.

Remember that as you change from model to model within a certain style (ICF, surfski, K1 vs. K2 vs K4, etc.) you may have to alter your paddle length as well.

4. Blade shape: There are many blade designs on the market. Some have a faster entry, some cleaner exit, some feel like they pull more, etc. Try a few out, often the nicer feeling ones cost more and are worth the difference. Many blades are made to suit a specific paddling style.

Two common shapes are;
  • Tear-drop: where the tip of the paddle widens out slightly relative to the base near the paddle shaft. This shape uses the knowledge that deeper water can provide slightly more resistance due to changes in hydrodynamics and the physical characteristics of water. A tear-drop shaped blade will be much more aggressive on the catch than a parallel blade, and much less forgiving to poor stroke mechanics.
  • Parallel: parallel blades maintain a relatively uniform blade width as the blade lengthens from base to tip. These blades are more versatile as an all around choice and in variable water conditions.
5. Blade pitch: this is a parameter used to describe any additional changes in effective twist angle within the length of the blade. Some blade will pull into the water (and toward the hull) using a rotation along the long axis of the paddle, while others will enter along the line of action exerted by the paddler.

Depending on your paddling style (especially set up and entry mechanics) you might prefer one over the other.

From my experience coaching flatwater and surfski paddlers, I have observed that paddlers who experience difficult burying the blade quickly (i.e. fast entry) or who initiate a pull back during the entry thus preventing full paddle immersion or who pull back horizontally with the arm as opposed to down and back with the back and torso tend to like more pitch on their blades. Typically, this tends to be newer paddlers and those who do not get a lot of technical feedback on their stroke mechanics.

6. Blade size: Hull speed is a function of force per stroke (the portion thereof that is transmitted to the hull) and stroke rate. Big blade often = slower rate, small blade often = higher rate. The trick is matching blade size to event distance, paddling skill level and torso strength.

For very skilled, strong and experienced adult men or genetically gifted and skilled women doing events of under 10-30 minutes a full size men's sprint blade is ideal.

For less experienced or less strong adult males doing events under 10-20 minutes or all adult men/women doing distance events (20 minutes or longer) a mid-size blade may yield better results.

For younger or new paddlers, a junior or small blade is often adequate and may yield better results.

For some workouts you may choose to use a bigger or smaller blade to stress your paddling technique and musculature more effectively or to address any particular strengths and weaknesses.

7. Finger guides: I advocate the use up tape for finger guides on the paddle shaft to facilitate proper hand position.

On the grip/twist side build up a slight ridge on the outside of the thumb (2-3 wraps of electrician's tape as a base then either fold or twist the tape to build the slight ridge, then tape over it again to smooth off the edges). Newer paddlers are best to use a small built up section (<1-2>7.

8. Shaft shape: some paddle shafts are ovalized while others are round. Comfort and ease in the "twist" is often best on an ovalized shaft. This can be aided on a round shafts by ovalizing the gripping side (twist hand) to allow you to control the paddle by rolling it through your fingers rather than flexion/extension of your wrist.

9. Offset: Offset is less common today than it was years ago. The offset angle refers to a deviation from the long axis of the paddle shaft, usually in the forward direction.

I believe the theory was to allow greater forward propulsion in the middle and back of the stroke. I can't say this fits with my current understanding of how a wing blade generates propulsion, unless the paddling style was very low and acted in a very wide sweeping stroke.

All that being said, there is still lots of room for personal preference and more room for inquiring minds to explore different combinations.

Alan


Alan Carlsson
Engineered Athlete Services

1 comment:

Tunder said...

Thanks for taking the time to put up such a great post. That's a lot of very good information that I hope to in the near future make sense of. All I need is for somebody to actually show me what you just said!