[Paddlewise] Dynamic Stability

Physical Therapy's definition of Dynamic Stability:

1. the ability that the body regains balance at the moment of giving any
perturbation.




The Mechanics definition:
The characteristic of a body, such as an aircraft, rocket, or ship, that
causes it, when disturbed from an original state of steady motion in an
upright position, to damp the oscillations set up by restoring moments and
gradually return to its original state. Also known as stability.


McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright ) 2003
by The McGraw-Hill Companies, Inc.

(Essentially if something disturbs the boat it oscillates less each time until
it resumes its original position.)


Paul and Rob, are either of the above definitions what you mean by "dynamic
stability" in relation to kayaks? Years ago I wanted to use "Dynamic
Stability" to denote how well a kayak tends to remain upright on its own (by
that I mean without input from the paddle) in rough seas, but then I
discovered it was a term already used in Naval Architecture and its definition
wasn't exactly what I had wanted to convey so I had to search for other terms.
Seakindly seems to fit better with what I meant. I originally wanted to use
Seaworthy but it turn out hat just means it is unlikely to sink not how well
it handles. In the mechanics definition above Dynamic Stability is a
characteristic of the craft and does not seem to concern to active
participation of a paddler and paddle. Possibly the Physical Therapy
definition would cover that.



I suggest we define what it is we seem to be disagreeing about before getting
down to the knock down drag out paddle battle.





> Paul wrote:
> My own experience is that dynamic stability (from boat speed) helps to
> overcome sea-state (clapotis & chop) - but is less useful in conditions of
> cresting side-waves & surf, and much less useful in wind gusts and willies.
> These situations benefit from a longer paddle (ie: longer than my last
> regularly-used Euro paddle).
>
> One vivid GP memory is sitting under a tall bluff and waiting out some wind
> 'dumps' that came down and hissed across the otherwise flat water - kicking
> up little whirls of spray. I've always remembered them with my reaction at
> the time 'sh#t - this has to be 50+ knots'. For a few minutes, I was in
> 'brace to survive' mode, low to the deck and GP held low & centrally -
> equally out on either side, as I was struggling to stay head-on to the
> rock wall and keep whatever shelter I could get.
>
> The ease of doing a slap-brace on either side with no hand movement - and
no
> wrist rotation (un-feathered GP, of course) was certainly something I
valued
> in that particular experience - and something I continue to think of as
> a benefit of the GP.
>
> Best Regards
> Paul Hayward, Auckland, New Zealand

Dynamic stability is not dependent upon which direction features come
from, be it beam, stern or bow. It is what it says it is, stability in
dynamic environments by actually paddling and utilizing water features,
not bracing and losing momentum, especially with an overly long lever
that offers slower cadence and the ability for the water to catch up
and control you. Use your lower body tension with proper posture and
the control surfaces of your hull to achieve stability while paddling,
not dumbing down your speed to get to where you need to be.

I was a safety boater at the Deception Pass Dash, an early winter race
in Washington's Deception Pass, a few years ago. I was given the
lousiest assignment possible, be the guy at Deception Island at the
mouth of the inlet where the wind blows hard and the swell bounced me
around for an uninterrupted 2.5 hours. Me and my 205 cm paddle. When it
came time to leave it was a slog to paddle across 30 knots of wind on
the nose to the shelter of the cliff a mile opposite. It's nice having
the cadence to actually paddle into the wind, across the current ebbing
against me and over the waves and boils. A long paddle, relying on
reactive techniques would truly have sucked. Some of the racers in
their faster boats got a ride on a powerboat from our position.

Cheers,

Rob G
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