Showing posts with label Kelly Slater. Show all posts
Showing posts with label Kelly Slater. Show all posts

Thursday, September 23, 2010

Dane vs. Jordy: Who Does Higher Surfing Aerials?

The biggest 2010 surfing event in the US was recently completed in perfect 6 foot waves at Trestles in Southern California. The surfing was innovative and exciting with technical and high flying performances, elevating surfing to a mesmerizing and progressive spectator sport.

This was the first surf event to use the new competition format, pitting the worlds top 32 surfers and 4 qualifiers against each other. If you want to find out more about the surfing World Championship Tour check out this video or head to the ASP Surfing website. The new format and fantastic waves brought the best out of many surfers on the tour.

Dane Reynolds and Jordy Smith were stand out performers, particularly in the air and that's where we want to go in this blog. Just like basketball slam dunk competitions, the higher the aerial maneuver the more exciting and better it is. Of course if the surfer does not land and ride out then it cannot count (similar to a missed basket in an attempted slam). The surfing judging criteria do not specify height in an aerial move as a criteria, but height above the wave definitely makes the move look more difficult.

In the video we have Dane and Jordy performing aerial moves at the Trestles Hurley Pro. Dane is first up and we will look at his first air. Jordy is third surfer up and we will look at his "Superman" air when his feet come off the board.



To compare these two aerial moves we will measure height above the top of the wave at the peak for the air. We will do this because the camera footage allows us to see both the surfer and top of the wave in the same image for both surfers.

To measure their height above the wave we have to make some assumptions. Firstly we need to estimate the length of their surfboards. We will use this length to scale the video and allow us to measure height.  We will assume that the board Dane was riding was 6 foot 1 inch (73 inches) Al Merrick Proton that he refers to in this video. We will assume that Jordy is riding a 6 foot 2 inch (74 inches)board as he talks about here.

Take a look at the images below. First Dane and then Jordy.





To compare their aerial heights we measured the height of their hips above the wave. Dane and Jordy both get their hips just under 5 foot (60 inches) above the top of the wave. Dane may be a little higher, an inch or so, but as the video of these aerial moves was taken from different positions and with different fields of view, we need to allow for  some error. So we will have to say that both got about the same height above the wave.

So who did better? The judges scored Dane's wave with this aerial in round 3 of the event as a 9.33 out of 10 and Jordy's wave with his "Superman" air, also in round 3, as a 9.60. A wave is not judge only on one move though(unless its the only move) and Jordy did bigger moves on the rest of his wave than Dane. So maybe height of an aerial move does factor into the judges scoring and in this case the judges scored both waves high because of the incredible amplitude that both surfers reach.

Of course surfing is not only about being in the air above the waves but also about the movement, flow, power and combinations on the face of the wave. The 2010 Hurley Pro at Trestles was not won by either Dane or Jordy, but rather by the master of surfing, Kelly Slater.

Kelly is currently leading the World Championship Tour ratings going for his 10th title, but Jordy and Dane (2nd and 4th respectively) are right in it to. We expect the surfing will continue to be as exciting as it was at Trestles with these three athletes pushing each other to greater heights and hope to be seeing and analyzing the first aerial move 6 foot above the wave.

Wednesday, July 28, 2010

Does Kicking Help to Paddle Faster in Surfing?

The world best surfer, Kelly Slater, whips around and starts paddling hard into a double overhead wave at Pipeline on the north shore of Oahu, Hawaii. His arms stroke deep into the water right next to the side of his board as he produces the speed needed to catch the fast moving wave beneath him. With another look at some video we also notice that he is kicking hard with his legs.

Getting up to speed

To catch a wave, a surfer needs to paddle the board fast enough to create the forward momentum that will ensure the wave carries the board and rider along with it and does not leave the surfer behind. The surfer must overcome the forces of inertia and gravity and match the speed of the wave as closely as possible. Large waves travel faster and therefore the board speed needs to be faster to catch these waves than to catch smaller waves.

A surfer increases his paddling speed by taking deep paddling strokes with arms close to the board and fingers together. This seems intuitive, but what about kicking hard? Does it really help to kick hard when paddling into a wave?

Slater kicks

In this video of Slater at the 2008 Pipeline Masters, watch how he paddles and kicks for every wave. From this video it is obvious that Slater kicks his legs when paddling into a large wave.



Why do surfers kick?

Kicking while paddling a surfboard has been carried over from freestyle swimming. A freestyle swimmer kicks:
  • To keep their bodies and legs floating high up in the water. This ensures the body maintains a straight line in the water, reducing drag.
  • To assist with body rotation and breathing. Breathing in freestyle swimming is timed with the kick.
  • Swimmers are taught to kick from the hips with slightly bent knees and an extended foot. Kicking from the hips produces the power which can translate into extra speed.
  • To increase swimming speed. Swimmers use a higher kick count to speed up in the water.
This may work for a freestyle swimmer, but a surfer may not get all the benefits listed above.
  • A surfer is lying on his board and is being kept afloat by the board itself, therefore kicking is not needed to stay afloat or to support the hips and legs.
  • Once again as the surfer is on his board with his head and chest up, he does not need to use a kick for breathing and he will certainly not want to rotate his body too much as that may destabilize him on the board.
  • On almost any surfboard that can be stood up on, the surfers hips will be pinned to the board while paddling and only his feet and knees will be in the water (depending on the length of the board). It is very difficult to kick from the hips while paddling a surfboard and therefore difficult to create the same kicking power as a freestyle swimmer.
Therefore the only advantage to kicking while paddling a surfboard may be to increase paddling speed.

Kicking increases paddling speed

A  2010 study done at Griffith University in the surfing Mecca of Queensland, Australia  - Loveless, D., Minahan, C. (2010). Two reliable protocols for assessing maximal-paddling performance in surfboard riders, Journal of Sports Sciences (in press), suggests that kicking while paddling gives the surfer a 9.2% increase in paddling speed over paddling with arms alone.

The study looked at eleven young competitive male surfers and tested them in a field test in a 25m pool. The participants were asked to paddle as hard as they could for 10 seconds. Their paddling speed was measured with a tether like device which was connected to their waste and pulled a cable attached to a spool. The spool contained holes 1cm apart and an infrared light measuring sensor recorded the speed at each interval that the light could pass through the holes. The faster the spool spins the faster the surfer is paddling.

Over this 10 second interval the surfers averaged 1.73 meters per second when paddling with arms alone and 1.89 meters per second when paddling with their arms and kicking hard too. A 9.2% improvement.

So kicking increases paddling speed and Kelly Slater kicks so it must be good.

Surfers don't paddle into a wave for 10 seconds.

If you surf you will know that most of the paddling you do is out to the line up or to get into position for a wave. The sudden burst of paddling to actually catch the wave is likely to last at most 2 or 3 seconds.

From the Griffith University study we can see that kicking while paddling adds speed and allows the surfer to cover more distance (0.8m-1.6m) over a 5 or 10 second period. This will definitely help a surfer get into position for a wave or win a paddle battle for priority during a surfing competition, but does it help a surfer when paddling to match the speed of a wave?

If we go back and analyze the video above we can see that Slater paddles and kicks to get into each of his waves for at most 2 seconds. Theses first 2 seconds of paddling from a resting position are used to get up to maximum paddling speed (this can be seen in the Griffith University study graph on page 54) and therefore the surfer does not get the same 9.2% benefit that he would get over a prolonged 10 second paddle. The advantage will be less and will depend on how much more acceleration can be gained by kicking.

The average advantage of kicking over a 10 second period therefore cannot be used as proof that kicking while paddling will help a surfer catch a fast moving wave.

To kick or not to kick

Unfortunately the Griffith University study does not compare the acceleration that can be gained by kicking while paddling but we can assume that there is an advantage here. Even if it takes the same amount of time, say 2 seconds, to reach maximum paddling speed with kicking and without, the fact that the maximum paddling speed with kicking is higher suggests that the acceleration with kicking will be greater. In other words a surfer kicking will get to a higher paddling speed in the same amount of time than a surfer that uses his arms only. And a higher paddling speed is better for catching larger waves.

The study and physics suggest that if a surfer can kick hard while paddling he will gain an advantage however small it may be. Of course if the kicking destabilizes the surfer on the board or disturbs their arm paddling rhythm then it may in fact reduce paddling speed and make it hard to catch the wave.

The size of the board is also a relevant factor in deciding whether to kick. A good kick can only be maintained on a shorter board where the surfers knees are in the water and not on top of the board. The surfer is already restricted in kicking from his hips as they lie on the board, if the board was also under his knees he would be forced to kick the surface of the water and create turbulence behind him rather than using his feet as paddles just beneath the surface of the water.

If you are a surfer and have a video camera, get into a pool with your surfboard and line up your camera on the side of the pool. Do not push off the pool wall, but paddle straight from a still start for a measured distance say 10 feet or 5 meters, using your arms only and then using your arms and kicking too. Measure and compare the time it took to cover the distance and the speed attained at the end of the distance using a basic video analysis software and see whether kicking to catch a wave would work for you. Let us know what you find out.

Tuesday, April 6, 2010

Progressive Surfing Needs Analysis

The Surfing World Championship tour is currently in the middle of the second event of the season held at Bell's beach (made famous in the movie Point Break)and by now many surfing fans will know that the judging criteria for 2010 have changed.

If you are a surfer or simply a fan of competitive surfing and the likes of Kelly Slater or Mick Fanning then you will know that the Surfing World Champion is determined by the overall points winner of a 10 event world championship tour.

Each wave in a man on man competition in surfing is scored as the total of points for 2 waves. Each wave is scored out of a maximum of 10 points. Judges now reward progressive and aerial maneuvers with more points. So one extremely progressive, difficult move can potentially score a surfer 10 points if he performs it perfectly, lands it and rides out. Surfing judges use the following criteria to determine the surfer's wave score:
  • Commitment and degree of difficulty
  • Innovative and progressive manoeuvres
  • Combination of major manoeuvres
  • Variety of manoeuvres
  • Speed, power and flow
The new judging system obviously wants to see surfers try different and risky tricks and combinations of tricks and will reward them for landing these tricks. Although from our casual observance it seems surfers get some points for trying progressive maneuvers, they definitely get many more points when they punctuate the trick by landing it and flowing back into another move or back into the wave itself.

The video below has some excellent examples of progressive aerial surfing, at Bondi Beach in Sydney, Australia, by some of the Worlds best surfers.


The importance in the judging criteria of landing moves such as those seen in the video, means that surfers will need to spend time working on their technique.

With the help of video analysis they can assess their aerial maneuver take off positions, the height they attain and other factors during flight such as rotation. Landing positions that will allow the surfer to ride out of the maneuver and into the next one, require excellent balance and technique. All these factors which will lead to progressive moves can and should be analyzed.

The analysis can then help them to add height or variety to their moves, impressing the judges further and blowing the competition away.

Most pro surfers have hours of video footage of themselves to analyze. However many of these are shot for cinematic effect and may not give the best angle for analysis. With the new criteria pro surfers will also want to get video that will give them the best analysis possible.

For the rest of us, watching video of pros and capturing video of ourselves for analysis will allow us to improve our technique and general surfing. Please browse our site for suggestions on cameras and how to get great footage to do just this and contact us to let us know how you are getting on.

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