Saturday, April 5, 2008

A Paddle Offset Study

45° versus 0°

Coke vs Pepsi. Kayaks vs Canoes. Republicans vs Democrats. Star Wars vs Lord of the Rings. These are the timeless debates that occupy our time. These debates have no real answer, which is why they’re fun to argue about. Let’s add the 0 degree vs 45 degree paddle debate to that list. Ok, ok – that one is not quite as fun to argue about. Still, that has never stopped the instructors here from debating the merits of each. (Of course, instructors will debate anything – I once overheard two instructors arguing over what color moss, green or brown, was more conducive to seal launching)

Anyway, instructors fell into three camps in this paddle offset debate – a zero degree paddle would enable beginners to learn quicker; the forty-five degree paddle would enable beginners to learn quicker; it didn’t matter what paddle they used – it was simply a matter of instruction. After about six months of back and forth debate, we decided to design an actual experiment to put the argument to a test.

Typical spirited debate

The prevailing hypothesis was that a paddle with a zero degree offset would make learning to kayak easier. We reasoned that:

• Novice kayakers would be able to go straighter faster with a zero degree paddle
• Novice paddlers would have better blade control with a zero degree paddle and they would therefore execute better strokes.


Method

Only new paddlers participated in this study. At the beginning of our novice clinics the participants were taught how to wet exit but no other instruction was given before the test. In the test we had each participant paddle thirty yards out on a lake, pass behind a fixed object and paddle back to the starting point.


Each participant completed this loop twice, once with a zero degree paddle and once with a forty-five degree paddle. Half of the participants used a zero degree offset first and half started with a 45 degree offset first. After completing the second loop each participant selected a preferred paddle to use for the rest of the clinic.


The participants were video taped just in case something funny happened that we could post on Youtube. Ok, that’s not true. The tapes were used to determine the elapsed time for each trial and to categorize the quality of the strokes executed and to identify the paddler’s final paddle preference. The elapsed time was from the moment the participant’s boat left the beach until the boat touched the beach upon the return. Stroke quality was judged on three dimensions: how well did the paddler reach out on the stroke, how vertical was the stroke, and was the paddle blade completely immersed.


We ran 34 brave volunteers through the experiment in an attempt to answer four questions.

  • Since we ran the paddlers through two trials, did they learn to go faster between the first and second run?
  • Since we had paddlers use two different paddle offsets, did they go faster with one offset over the other?
  • Were there differences in the “quality” of the paddle strokes between the different offsets?
  • Which paddle did the beginners choose?


If you’re playing at home, feel free to take a guess before you see the results. (If your answers are correct please fax your resume to human resources at NOC)

Humm....

Results

Question 1: Did paddlers learn to go faster between the first and second run?

Answer: No. Keep in mind that no specific instruction was given about the use of the different paddles. We thought this would have made the 0° paddles more effective because the 45° paddles require a twist with the right hand to get good blade orientation to the water with the left paddle blade. We expected that without instruction new paddlers would struggle with this twisting movement. The lack of instruction about the twist did not seem to matter though.

Question 2: Did one offset enable paddlers to go faster than the other?

Answer: Yes and no. There was no significant difference in the speed with which a subject completed their first run using either a 45° or 0°. However, their was a difference on the second run. The paddlers who started with 45° paddle and then used a 0° paddle were faster on their second run than the paddlers who started with a 0° and then used a 45°. This defied our conventional wisdom – we actually predicted that the opposite would happen.

Question 3: Were there differences in the “quality” of the paddle strokes?

Answer: No. The novice paddlers’ stroke quality was equally modest.

Question 4: Which paddle did the beginners choose?

Answer: Both. Given a choice between 45° or 0° paddles, 18 of 29 paddlers preferred the 0° paddle. This is not a significant difference in preference. (In the videos it was impossible to determine the choice of five paddlers.)

Final Thoughts

The results of our study were inconclusive, and probably raised more questions than answers. We are already planning a second test and are exited about the chance to apply the scientific method to other debates about kayak equipment, boats, and paddling technique.

So in conclusion: Coke, Kayaks, Democrats, Star Wars, Green Moss, hand paddles.


More details here for those of you that just need to see the numbers:

Sample Video of a volunteer during the study


(Note: The Instructor in the kayak is tethered to a cable that is hard to see in the video. This was anchored at the waterline for every test so the the distanced around the instructor was roughly the same for every test.)


Figure 1
Average Elapsed Time for loop 1 versus loop 2 across paddle offsets


Figure 2
Average Elapsed Time for loop 1 versus loop 2 for both paddle offsets

Table 1

Average time for 0° versus 45° for loop 1 versus loop 2

Used 0° first
(Trial 1) M = 34.8, SD= 8.6
45° (Trial 2) M = 34.2, SD = 8.5

Used 45° first
45° (Trial 1) M = 30.5, SD = 6.3
(Trial 2) M = 29.3, SD = 4.5

Were there differences in the “quality” of the paddle strokes? What of the other data we collected? The table below listed the number of strokes scored as having a vertical catch, good extension and full immersion. As would be expected, before any instruction, the stroke quality for beginners was pretty modest. However, to the point of this study there appears to be no difference in stroke quality for 0° versus 45° paddles.

Table 2
Used 0° first 0° 45°
Catch Vertical = 25 18
Extension = 7 3
Catch Immersion = 38 30
# of strokes scored = 54 54

Used 45° first 45° 0°
Catch Vertical = 21 20
Extension = 1 2
Catch Immersion = 26 26
# of strokes scored = 48 48




Table 3

Preferred 0° Preferred 45°
Used 0° first 8 6
Used 45° first 10 5



Note: In the videos it was impossible to determine the choice for 5 paddlers.


2 comments:

sirtet said...

Great test...
I look forward to see more of these, and a deeper study on Feather.

Have you talked to manufacturers as well?

The slight preference of 0° in the end could come from the thinking of beginners, that the feather does not make sense at all, that these 45° paddles were there just for the test.

But the feather has its purpose i think, since the pivot point is in the shoulder, and not in the center of the paddle.

What were the arguments of the 0° instructors, why 0° should be better?



cheers by toro, from Kanuschule Versam, Switzerland.

ps:
there's a good reason why jim snyder named one of his paddle designs S.O. Terrik...

Anonymous said...

I noted that those who used the 45 degree paddles first, used less paddle strokes to complete the course than those who used the 0 degree paddle first.

I am an exercise science graduate at UK (Kinesiology) and would be interested in discussing a collaboration effort to study muscle activation through the shoulders and thoracic trunk using each of the paddles you tested. I'm curious about efficiency and force production relationships between the paddles. please contact me regarding such a study