Re: [Paddlewise] 2ndry stability

Nick wrote:
> The advantage of starting with rigid hunk of meat is that all other
> conditions can be extrapolated from the response of the boat with the
> meat. It takes effort but by looking at information such as the slope
> of the curve and the area under the curve you can predict the
> response of the boat if the person does more than sit there like a
> rigid hunk of meat. The hunk of meat is just a useful non-subjective
> starting point.

I've found through my experience (disclaimer non-pareil) that when I start
out in a new "tippy" kayak, that I am in fact the rigid hunk of meat you
mentioned, i.e., filled with tension, fear, and a sense of cold, miserable
impending doom. (The rigidity being a firmly-fastened set-up for the easiest
roll I know).   The "hunk-of-meat" lack of subjectivity is indeed valuable,
but when I am that hunk of meat, notions are quite objective, if not
blasphemous.   But seriously, the curves are indeed valuable (but do take
effort to read)  for a sense of what one is getting into, but stability can
be "learned", and for most paddlers, an unfavorable curve may simply keep
them from ever giving a fine boat a chance-- In a vessel so connected to
conditions and "captain's skills", stability is the other 1/3 of the factor
(and the key is to honing the captain's skills in harmony with ambient
conditions.)  Much like learning to ride a bike, (a skill I have mastered,
if I may brag), one can get-used-to a 'tippy' kayak with LOTS of patience
and practice.

Snip:
> I will admit that the best way for any individual to determine how a
> boat feels for him/herself is to get in the boat and see how the boat
> feels for him/herself. But there are a lot of boats out there and if
> you are looking for a new boat, you really don't want to have to try
> every one before choosing the best one for you. Knowledgeable
> inspection of stability curves is one way to reduce the field. Or if
> you have a design you want to change by some criteria, knowing what
> aspect of the stability curve represents that criteria will save a
> lot of time testing boats.

Yes, actually trying a kayak is best-- perhaps we'll all agree. With kayaks
whose curves exhibit low initial stability, the "trying" may be quite
trying, and negative opinions can be formed hastily (and/or for good reason
as well!)  Patience, again-- just as when bicycling was learned.  My
experience with very tippy kayaks comes from learning to use various
traditional kayak replicas-- one in particular was calculated as having -.03
meter/kilograms of righting moment with 1 degree of heel (as per Zimmerly's
calculations of the MacKenzie Delta Kayak CMC IV-D-1058, as published in
Eugene Arima's "Inuit Kayaks In Canada", 1987 (Pg. 165).

Had I read of this stability "fact" prior to 'wasting' so much time building
a replica of this kayak, I perhaps would've dismissed it as "impossible."
I've found the kayak very possible indeed,(though with practise,) and I
attribute my ability and love of this kayak to perserverence, patience, and
a large chunk of naivete regarding stability curves and their meanings
(e.g., The coyote never falls until he realizes he has over-stepped the
cliff)

A stability curve does say a lot-- certainly more than the holy but
insignificant measurement of "beam" does. (I have a 19" wide kayak that's
tippier than my 15-1/4" wide kayak. [Heresy!])   As Nick said, there is no
substitution to trying the kayak yourself.  He also says that it takes
effort and knowledge to use the curves.  I personally think that for the
average paddler-non-naval-architect, that the kayak could be paddled
extensively before the curves for the particular design can begin to make
practical sense.  (Lest we presume to understand the "curve" before we
really understand the kayak.)
    Harvey Golden
            www.pacifier.com/~qayaq



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