[Paddlewise] Newton, Paddles, feathers, and some thick air

Thanks all for the discussions on paddle size, forward stroke mechanics etc.
As usual very entertaining reading. I often get accused of ranting when I
post to this list. At the risk of ranting again here are my thoughts:

There are some very interesting discussions on how paddles work on rowing
sites. Rowers worry about how their blades work a lot. Try for example:

http://www-atm.atm.ox.ac.uk/rowing/basics.html#section1

A paddle stroke follows Newton's 3'rd law of motion: ie 'Every Action has an
equal and opposite Reaction'. You move water one way with the paddle and the
boat moves the other way. The whole 'slippage' thing is a misguided way of
looking at the problem. All paddle blades slip - that is how they work ...
they accelerate water by **moving**. Accelerate water one way, boat goes the
other. Momentum of boat forward equals the momentum of the water **moved**
by the paddle backwards. Thus you have a simple choice of blade size: for
the same drive either accelerate a lot of water with a big blade moving
slowly, or accelerate less water by moving a smaller blade more quickly. The
speed you can move the blade is however important ...

I do a lot of swimming and one thing you learn quickly in the pool is
swimming harder doesn't make you go faster - swimming more efficiently with
less drag makes you go faster. Nothing funnier than some klutz flailing away
churning up water in a pool, making lots of splash and going no where, very
out of breath, not very fast. To swim fast you have to develop feel for the
water moving past your body. In a kayak you have to develop feel for water
moving past your paddle. The catch is critical, if the blade isn't already
moving as fast as the water is going past it when you catch, it is going to
slow you down. The faster you go, the faster your catch has to be. Ever
notice how a blade feels different moving up and down stream in moving
water? The relative speed of the water past the boat is the timing for the
catch and speed of the stroke. You need to develop a feel for that from the
blade. If you have the power to stroke a larger blade you can, if you don't
its just going to slow you down. Get a blade which matches your power, or
how hard you want to work. Once you have accelerated a single stroke's water
get the blade out of the water because at that point it's again just slowing
you down. The rule of thumb that the only stroke behind your hips is the
stern rudder is worth remembering. I think that avoiding drag at catch and
recovery, rather than more power is the main reason why greenland paddles
and wings are so efficient, that and that they promote torso rotation as the
source of the power. If you think rotation, then the whole concept of
pulling or pushing with your arms also becomes somewhat less relevant.
Greenland blades (which I use almost 100% of the time) have the added bonus
that they give you a lot of options - you can vary the blade size and angle
of attack dynamically to match stroke rate and power to boat speed. I think
greenland blades are however an advanced blade - they require a lot of
finesse , or maybe sensitivity is a better word, to get the most out of
them. I didn't know it at the time but it took me 500 miles or so before I
got any sort of proficiency with a greenland paddle and I think you never
stop learning with one.

Re: feather - There are good reasons not to use a feathered paddle (I rarely
do), but wrist pain is in my opinion not one of them - there is **no**
reason ever to cock your wrists to set a feathered blade (except perhaps
when rolling with one), or indeed I think to spin them in your hands!?! Sore
wrists are a technique problem not a paddle problem (rotate your torso and
move your arms to set the blade, not your wrists). Critically though if you
are interested in performance, aerodynamic drag of unfeathered blades in the
air really does slow you down. The greenland paddle's greatest flaw is that
into the wind it is a real drag (sorry couldn't resist). You can argue till
your blue in the face about blades getting buffeted around, winds from the
beam, controllability in gusts, that isn't the problem - its just drag. What
is not immediately obvious is that your boat's speed itself and the
resulting apparent wind is important. In flat calm conditions if you are
paddling hard at say 5 knots then the apparent wind you feel on your face
(in flat calm conditions) is 5 knots.  If you are paddling hard down stream
in 5 knots of tide then you are feeling an apparent wind of ten knots
(that's top end of force 3 in your face in flat calm conditions!) You could
argue that the un-feathered blade acts like a spinnaker when going downwind,
but its clear that this is less valuable - going at five knots in a five
knot tail wind the apparent wind at the kayak is zero. No drag, but no
benefit. I prefer a greenland paddle for a number of reasons, but feathered
blades really are faster.

;-)

Colin
57º19'N  2º10'W

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