Long or short pull?

You can’t escape drag…

because drag is part of the word dragon.  Haha!  But seriously, dragon boat is a sport with some serious drag factors to consider primarily in terms of water drag upon the dragon boat itself.  This, however is not the topic of today’s post.  This post will focus on various paddle philosophies in terms of paddle time spent in the water vs out of the water because going fast means maximizing propulsion and minimizing retropulsion.

Excess time spent in contact with the surface you travel upon WILL slow you down

Excess or inadequate time spent in contact with the surface you travel upon may slow you down!

Pull and Recover

Two basic aspects of the stroke technique involve putting the paddle in the water, doing work, and then taking the paddle out to set up for another stroke.  You can’t escape this basic fact, but there are countless ways to make it happen.  Very few of these methods ACTUALLY result in better performance.  The key points to consider are that in one stroke cycle, the athlete transmits force to the water via the paddle in an efficient way to minimize fatigue and use good mechanics and then efficiently move the paddle through the air to begin the next stroke cycle.  Notice how the word “efficient” is a big deal with both pull and recovery.  Every coach seeks to instruct their athletes in the “best” and thus most efficient method for the stroke cycle (of course TBD), but here are some common pitfalls that may help guide your decision to adopt a certain style of paddling in hopes of taking better strokes.

Style 1: Long Pullback

–  This style involves the paddle blade entering at positive angle up front and pulling the blade back to exit at or after the hip, often times involving increased trunk de-rotation or sitting up vertically at the exit to allow for this increased paddle displacement.  It’s a style that is more prominent in smaller paddling craft than dragon boat.  (more on this later)

–  Possible benefits: increased distance of pull through the water may translate to more work performed (force x distance).  Larger amplitude body movements may utilize more muscle groups, reducing single muscle fatigue.  More distance traveled by the boat per stroke means less strokes performed over the whole race, also possibly reducing fatigue.  Slower rates associated with longer pulls may mean paddlers can synch better and use better technique per stroke.

–  Possible drawbacks (no punning around): more work means more force applied over a distance, per stroke.  Doing more work per stroke may actually mean more fatigue by the end of the race depending on what zone of intensity you are working in and what energy stores your muscles are relying upon the most (physiologically less efficient).  This style also relies on longer recovery distance and thus time, reducing the paddling rate and possibly average power.  Some may argue that the long stroke pulls the boat down or reduces lift of the hull, but it seems to be a moot point here’s why.

–  Make it good:  Are you performing more work, more efficiently than with a shorter stroke?  Are you propelling the boat without dragging it down through the pull phase?  At higher boat speeds, you must be skilled enough to exert enough force on the water to avoid from having your paddle actually slow the boat down.

Style 2: Dippy Stroke

–  This style minimizes the pullback at all costs because of some various studies on the power curve during a paddle stroke that correlates directly to the angle of the paddle in the water.  Paddles anchor up front at a positive angle and the exit is completed by or around mid thigh if not sooner.

–  Possible benefits: the rationale I’ve heard with this style is that if positive to perpendicular paddle angles provides the MOST force you can transmit to the water in a stroke, then everything involving negative paddle angle is a waste of energy and should be avoided.  Short strokes also makes higher rates easier to achieve, which may lead to higher average power (work performed over time).

–  Possible drawbacks: faster rates mean more attention to speed of movement.  It’s been well-established that faster movement reduces movement accuracy.  In less-trained paddlers, faster paddling may mean sloppier paddling causing a drop in efficiency and thus average power.  If you are paddling quickly in an inefficient manner, you will get very tired, very quickly.  Not something you want to happen exactly before you cross the finish line.

Make it good:  You have to be skilled enough at higher boat speeds to apply force to the water in a very short amount of time.  You must also be skilled enough as a crew to stay in time to maintain peak average boat power from being N*Sync.

The Snail and Cheetah

Analogy time!  Mr. Snail crawls on the ground without ever stopping contact with it.  I am no snail expert, but they seem quite efficient at crawling for hours at their top speed across long distances (for them) with minimal physiological reserves (no fat, small organs, low carb diet).  They are very efficient at going slow with permanent contact with the surface they are travelling upon.

Now take Mrs. Cheetah.  She blazes around the plains at highway speeds for short periods, making very short but forceful contact with the ground.  This performance is short-lived and fatiguing no-doubt, but wins the race to the weakling gazelle.  If the cheetah and snail were the same size and wanted to race who would win?  Who would care?  It’d be cool to watch!

Maybe a more tangible and intuitive analogy comes in terms of running, something most of us can do or have done.  To run like your lift depended on it, the average person just does it.  No thinking about cadence or forefoot vs barefoot vs heelstrike technicalities, just go all out.  If you were to travel 100 meters as fast as possible, would you try to double-foot long jump the whole way?  No!  While you are powerful every time you move, the energy spent and time spent doing it is not efficient.  Would you try to squeeze in 300 steps within the 100 meters as quickly as you can?  Also unlikely.  You’d get very winded and not be able to move fast because you have very little power behind every stride.  Your body naturally finds a cadence and ground contact time while you give your best athletic effort, to get you moving as fast as you can.  Specific training enhances your ability but doesn’t radically transform your running style.

In sum, paddling with the extremes of long or short pulls may diminish your overall efficiency unless you are specifically trained to maximize performance using those styles.  For recreational or new paddlers with less training, the better and more efficient stroke to utilize is likely a middle-ground, nothing-too-special stroke style.  It’s my opinion that outlier styles are best left to athletes with performance capabilities also far exceeding that of the average paddler or team.

Don’t forget what boat you’re in

One important point that I think many people overlook is quite simply that a dragon boat is not an outrigger or C1-4 craft.  The aforementioned boats have less drag than dragon boats but also much less mass.  Less mass means less inertia, or the force required to change the object’s state of motion.  I have no specific numbers to prove this, but am guessing that if a fully loaded dragon boat and OC-1 were travelling at the same speed, and all athletes stopped paddling at the same time, the OC-1 would drift to a stop before the dragon boat.  If this were true, it’d mean the OC-1 had greater relative water drag to overcome it’s inertia than did the dragon boat.  What this also would mean is that with every recover phase of the stroke, the OC-1 will tend to scrub more speed than will the dragon boat.  This means the OC-1 paddler wants to maximize pull phase time and minimize recovery time.  The dragon boat paddlers have, in this regard, a luxury of being able to decrease time in the water and lengthen time during recovery with less change in boat velocity if racing against the OC-1.

Does paddling as if in a much smaller craft translate directly to the larger craft?  Perhaps but perhaps exceptions can be made with little consequence.

5 responses

  1. I think you have really opened a can of worms here Geoff. There are as many opinions about this as there are paddlers in a regatta and very little data to back up the opinions. There’s also an easy answer – paddlers need to paddle at a rate & stroke length that delivers maximum total power. The force on the blade depends on the difference between paddle speed and boat speed so at higher boat speeds you need to pull faster and probably longer.

    The other consideration is that the force at the start of the stroke is about double what it is near the end of the stroke (see the research done by Sarah Ho). So pulling further back is likely to be less efficient than reaching further forward – but over reaching will also be counter productive. There is some research on OC stroke rates and length http://researchonline.jcu.edu.au/12015/ but this does not give any clear answers.

    I did some experiments with 2 dragon boat teams (single paddler and boat 1/3 loaded) and found that paddlers with longer strokes got faster times and when repeating the test a few months later with 1 team, those that improved their time had also lengthened their stroke – but also made other improvements so difficult to pin down what was the major contributor.

    If you have access to an OC1 – I don’t 😦 – you could fit an accelerometer (any iPhone or android phone) and do a video analysis for a few strokes. From the video you can get the stroke length and the cm/sec at which the paddle is pulled. Correlating the three parameters with boat speed could be informative.

    So what’s right? Firstly, that depends on the paddler. Obviously taller paddlers should make longer strokes than the short ones. But some are more flexible than others so can comfortably reach further. I ask paddler to reach as far forward as they can whilst still feeling strong. Paddler strength and position in the boat also matter. There is aeration further back so the paddler there need to pull faster (and dig deeper) to exert the same force on the blade.

    It’ll be interesting to read what opinions other readers of your blog have.

    June 1, 2014 at 3:05 am

    • Geoff

      It most certainly is a can of worms! Great points as always, Jacob. I agree 100% that “the best” stroke is whatever literally results in the best performance, from a physics standpoint. The physiological toll of paddling a certain way is something that can be trained for, but the physics can’t be changed.

      I have seen you’re a reader of Yohei Rosen’s blog as well and I know he’s done some work with accelerometers, but unsure if he has compared 2 different craft. I think many coaches read studies like the ones you mention and interpret the results to the extremes, hoping that it will lead to maximal improvement (ie just cut out the back of the stroke entirely because the force curve is half that of the front). Unfortunately, many coaches and teams adopt this extremist philosophy and spend seasons working on something that is based on what I feel is a flawed perspective. Part of trickiness is the nature of that bell-curve of performance between long and short strokes. Team “A” may take a long stroke in the back using a slower rate and have the same net power as Team “B” with a short stroke up front and higher rate. As you vary boat speed with everything else constant and equal, I hypothesize you will see performance differences emerge. Just waiting for some crazy person to put such a comparison together objectively….subjectively, watching elite canoe racing is great because the long distances travelled and fairly consistent split times allows for some very noticeable differences in technique to result in different performances mirroring what we are debating here.

      I think your suggestions for your paddlers is plenty sound. You ask them to do what works best for their bodies (acknowledging different physical traits and capabilities), and you ask them to use technique that is based on best-physics concepts.

      A motorcycle racer I knew once said, “Just when you think you ironed out all the problems, you get faster and another set of problems rear their ugly heads.” Competing at low speeds with novice crews demands different considerations for paddling style than does competition at the international level, yet so many coaches of novice crews push styles they’ve seen the pro’s use, and I think it is inapPROpriate, haha.

      June 1, 2014 at 8:12 am

  2. Hi Geoff. Your insightful comments always cause me to question my statements – which is a good thing. This time you made me think more about why it is that the fore profile for a stroke is the way it is. It is probably obvious as it is easier to pull hard while the paddle is well in front of you that when it is past the thigh. But good to verify that that’s what actually happens. So I had another look at video I took for stroke analysis. I just looked at the pull from when the blade is fully buried until the paddle reaches the knee (and angle from vertical is about 20 degrees) and comparing this with the remainder until the paddle starts to be pulled out of the water. I found that the first part of the stroke is about 35% quicker (measured in cm/sec) than the second part consequently about 80% more power gets generated. Which is consistent with paddle force data profiles.

    Maybe instead of trying to get paddlers to make longer strokes, we should encourage them to pull harder in the 2nd half of the stroke. This will also result in a slightly higher stroke rate but without reducing stroke length.

    I also noticed that there is quite a range of pull speeds (and of course stroke lengths). As the dirty water near the back of the boat requires greater pull speed to generate the same propulsive force, there may be an advantage to place certain paddlers near the back of the boat. However, as the frothy water is mainly near the surface, a better strategy maybe to simply push the blade a bit deeper – or let the back six use longer paddles.

    July 1, 2014 at 6:48 pm

    • Geoff

      I have worked with coaches who emphasize increasing power of pull leading up to the exit. Others have described it as trying to steadily accelerate the water thru the pull to exit. Yet another coach I know believed the importance of such a paddling technique was to eliminate drag from paddles moving too slowly thru the water and slowing down the boat.

      One reason I believe the first power phase of the pull is so short and quick is due to the relatively short time of positive to perpendicular paddle angle and the constraints of body mechanics involved.

      One thing I have noticed is that many paddlers believe they are fully buried when at race pace but are actually needing to dig farther down to submerge the blade completely due to wake and turbulence from paddlers ahead (nevermind cavitation).

      You’re right that no matter the stroke length or depth of pull (beyond full bury) it comes down to how the paddler finesses/powers the blade in the water to yield optimum force transfer…something of an art form in itself!

      July 1, 2014 at 10:32 pm

  3. I wish there could be a video you can share for this as well. Would love to see the difference in stroke techniques as much as they are easy for experienced paddlers and coaches to visualise. I think it is a current challenge for me to visually engage them to try these techniques on very novice paddlers that I am coaching right now. Cheerios for the post!

    December 27, 2014 at 7:30 am

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