[Paddlewise] paddles

I am passing on this message from Margi Bohm that may be of interest to
readers of Paddlewise.

Margi's text begins here;


 One of our club members forwarded your discussion of the efficiency of
prop
(or wing) blade Vs the conventional flat blade.  I found your discussion
interesting for two reasons (1) I am the flatwater coach at the Burley
Griffin Canoe Club here in Canberra, (2) I am a research scientist in the
field of fluid mechanics so should be able to understand the Jackson et al
paper.  Do you have a year on that publication?  I am very interested in
giving it a read.
I found your comments interesting and although I have not access to the
entire gist of the emails regarding prop Vs conventional blades, I have
taken the liberty below to suggest that there is more to maximising
paddling efficiency than choosing a paddle.  I feel that in the sea
kayaking community, much would be gained by a serious effort to teach
paddlers to paddle properly.  Having good technique inevitably reduces
injury and pains during a trip thereby enhancing enjoyment, especially in a
recreational environment.  I believe that technique coaching is really
lacking in the sea kayak community.
We muck around with boat (K1) and paddle performance (prop blade) under
marathon and sprint conditions, also in the absence of a research grant.
However, we search for a combination of boat design, paddle design, and
paddling technique that gives the paddler MAXIMUM average BOAT SPEED over
the distance of interest using REASONABLE EFFORT.  This is the key, I
believe, not only to enjoyment of ones sport, but also to success in a
competitive environment.
Our preliminary conclusions are that mathematically the efficiency of the
system as a whole is an optimisation problem that includes stroke and boat
performance and it is naive, in a flatwater racing environment, to assume
that changing one component of the system will alone bring about
dramatically improved performance.  For example, initial introduction of
prop blades into flatwater sprint paddling led to about 7% improvement on
K1 boat-speed over 500 m.  Improvements in boat design and paddling
technique lead to an overall improvement of almost 15% (over a decade).  We
are again going through improvements in paddling technique aimed at
optimising boat speed.  I do believe that we have yet to maximise prob
blade efficiency and there is still a lot of work to be done with
technique.
We have found using on water testing with heart rate monitors and
SpeedCoaches (that give boat velocity and stroke rate) that maximum boat
speed is often determined by a stroke rate that seems awfully slow.  And
different prop blade designs warrant different in water techniques to
maximise boat speed.  To further complicate matters, fine-tuning the system
is athlete specific.  For example, I have found that a stroke rate of 75
strokes/minute in a marathon environment gives me maximum boat speed at my
current strength, 80 strokes per minute over a 500 m sprint.  As I get
stronger, I should be able to rate higher or with more power but the bottom
line is that maximum boat speed depends on allowing the boat her maximum
run before re-entering the blade into the water.  As early as a few years
ago, the consensus was 100-120 strokes per minute on the 500 m!  If one
monitors boat speed at a stroke rate of 120/min, and then drop the rating
to 80 strokes per minute, the instruments register an almost immediate
improvement in boat speed to the tune of  at least 10 secs on the 500m
depending on athlete and conditions.  I have noticed the same phenomenon
in marathon racing.  As I get tired, my rating picks up to around 85
strokes per min and speed drops by 10-20 s/km.  If I drop the rating back
to 75 strokes/min, the speed picks back up again.
How does this pertain to the sea kayaker?  I have been to a few sea kayak
gatherings and have several friends who sea kayak and paddle flatwater
racing kayaks and I have paddled sea kayaks on a few occasions although
always with a prop blade.  My first observation is that most sea kayakers
do not paddle conventional flat blades correctly and an improvement in boat
speed (or in enjoyment of a trip because of improved efficiency) can be
achieved by simply learning to paddle the flat blade efficiently.  I feel
that moving to a prop blade carrying poor flat blade technique would
probably not improve performance and would probably result in the paddler
being much more tired given the same paddling distance - bottom line ...
decline in enjoyment of a trip.  Furthermore, prop blades really catch well
so given the weight of a sea kayak, the paddler has to be stronger to
execute a stroke.  Finally, poor technique, especially on the exit, can
lead to nasty injuries that in older people will continue to haunt them for
a long time unless due care is taken in treatment and recovery (an example
is scapula impingement of the shoulder - a common overuse injury in
kayaking and almost always related to poor technique).
I think that stronger sea kayakers who want to cover larger distances
should seriously think about using a prop blade BUT should ensure that they
learn the prop blade paddling technique first and become competent prop
blade paddlers.  I would suggest learning from an experienced flatwater
coach as these guys deal with prop blades all the time under all sorts of
conditions (yes flatwater paddlers do paddle in rough water and weather
conditions).  I do not think that a prop blade is a disadvantage in rough
water.  Whitewater paddlers use them in water much rougher than that
expected in a well planned sea kayak trip and rolling with a prop blade is
a bit different but certainly not difficult!  Same for surfing sea kayaks
with a prop blade - different but not difficult.  I find that the added
catch of the blade allows me extra instant speed so catching a wave is
actually easier than when using a flat blade.
For the person who paddles once a blue moon or hasn't the interest in
spending time to learn to paddle a prop blade, I would suggest sticking to
the conventional flat blade.  It is hard to hurt yourself with a flat blade
although learning to paddle and use it properly would only make the trip
more enjoyable.
This has turned out longer than I expected.  I hope you find my comments
useful and feel free to post them on this net if you think they are useful
to others.
Happy Paddling
Margi Bohm

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