Subject: Re: baidarka aleut paddle plans
From: James Mitchell (mariner@seanet.com)
Date: Thu Dec 14 2000 - 01:00:16 EST
Stefano, I can give you some help with that paddle if you would like. Have
built several of them now, based on Lew's design plus some modifications
that developed out of my testing. And anyone else, if you are interested in
purchasing one, contact me off the net at mariner@seanet.com. I'm not
trying to make money doing this, but I am interested in having more of these
paddles in use so we can all learn more about them.
----- Original Message -----
From: "Stefano Moretti" <stmoretti@tin.it>
To: <baidarka@lists.intelenet.net>
Sent: Wednesday, December 13, 2000 12:26 AM
Subject: baidarka aleut paddle plans
> Some time ago there was a long discussion thread on aleut paddles. Lew
> Plummer had detailed plans on DXF or other format and had promised - off
the
> list - to send a copy.
> Now, I cannot get in touch directly again since my adress list and mail
were
> all cancelled from my HD. So, excuse me averybody, I would like to ask Lew
> if I could receive thos plans so to start the paddle project..
> many thanks in advance, Stefano
> ----- Original Message -----
> From: Peter A. Chopelas <pac@premier1.net>
> To: <baidarka@lists.intelenet.net>
> Sent: Tuesday, December 12, 2000 6:31 PM
> Subject: RE: baidarka stability...
>
>
> > Chuck,
> >
> > There as a long and very detailed discussion of this subject over on the
> > Paddlewise list just last month, if you want to know more (probably more
> > than you want to know) you could go look at the archives there.
> >
> > There are a couple of interesting things that came out of the lengthy
> > thread:
> >
> > 1. The term secondary stability is unique to the kayaking community, it
> > appears in no other navel architecture or watercraft usage. I would
> > speculate this is because only in a kayak does it have relevance since
you
> > control the kayak with weight shift and body movements, this allows the
> > "captain" to control the craft (which really becomes an extension of
> > his/her body) through rough conditions in a way not possible with other
> > water craft.
> >
> > 2. It has no precise definition and therefore really can not be
measured
> > or rated other than subjective feel of the kayaker. Some have tried to
> > show correlation with the stability curves though others pointed out (me
> > included) there was no consistent measurable quantity that can be
> > determined from the curves. In other words, by looking at the curves
> alone
> > you could not say which kayak would have good secondary stability and
> which
> > would not, it is too subjective.
> >
> > I personally think a measure could be developed but it would take a lot
of
> > different kayaks, a lot of different paddlers, and a lot of testing and
> > cross correlation between different measurable qualities, not just the
> > quasi-static righting moment curves you see in SK magazine.
> >
> > I suspect however that the higher heel or roll angle that one feels
secure
> > or comfortable with in a kayak, the more most people would identify as
> > having good secondary stability. The perception of the angle of heel is
> > the important issue, if you can roll a kayak on it's edge and
comfortably
> > hold it there, it feels like it has good secondary stability. OTOH,
even
> > if a kayak is rock steady at low angles of heel but you find you can not
> > hold it on it's edge, most would say it has high initial stability and
low
> > secondary stability.
> >
> > There are similar terms used in Naval Architecture called initial and
> > overall stability, which do have definitions but are not quite the same
> > thing. Most text books define initial stability at heel angles less
than
> > 10 degrees, and overall stability as the maximum righting moment
achieved
> > by the hull design beyond this 10 degrees. Of course in just about
> > everyother water craft, and certainly virtually all commercial vessels,
> you
> > can not apply a righting force as you can with weight shift and bracing
in
> > a kayak. So the term overall stability likely has another meaning in
the
> > mind of a hull designer I would guess, than secondary stability does to
a
> > kayaker.
> >
> >
> > Peter
> >
> >
> >
> >
> >
> >
> > On Monday, December 11, 2000 7:06 AM, Chuck
> > [SMTP:Sparky@thewizardworks.com] wrote:
> > > Hello all...
> > >
> > > I'm a bit confused as to the differences between initial and secondary
> > > stability. Might someone clear this up for me?
> > >
> > > Thanks!
> > >
> > > Chuck
> > >
> > > -
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> > >
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> >
>
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