Re: [Paddlewise] Group Paddling - folders stability

John Winters wrote:

> >Which bring me to something, John, that you said in your early posting,
 "Many paddlers achieve this
> >result by packing their boats with waterproof bags along the interior
> >sides
> >of their rigid boats."  I have never seen anyone do that in a
> >hardshell.
> 
> Perhaps this has to do with ignorance. I do this on my boats when I do not
> have a sea sock or pod. I use a multitude of small gear bags. Some boats,
> may lack enough beam for this kind of thing but foam sheathing glued to the
> hull sides to reduce volume also works. Reducing the floodable volume in
> the boat ios the objective. I doubt if most paddlers understand or consider
> the effects of free surface in their boats.  Most production boats don't
> come with methods to attach side bags, sea socks, or pods and that seems to
> me a serious omission.
 
> I cannot say why builders of hardshells fail to recognize the importance of
> flooded stability. As Ralph points out, all they need do is look at folders
> to see them in use and apply the same principle.

Well, as I pointed out, Bavaria does or did that (I haven't seen their
kayaks in awhile).  All it takes is to glass in some nylon twine or
webbing straps every 2 feet or so along the sides inside the kayak. 
Sponsons than can be added for that desired effect. I found very
interesting your comments the relative instability of bouyancy located
at the ends of the boat and the free surface inside the cockpit. 

> 
> Please don't call internal buoyancy bags sponsons. Sponsons attach to the
> outside of the boat. Buoyancy bags and tanks attach inside.

I would love to and Webster's dictionary (and I am sure all naval
architecture glossaries of terms do too) but sometimes things get called
something and the label sticks and we just have to start using the term
in the corrupted way.  :-) 
But I do appreciate that there is a distinction...anything to get away
from the infamy the term has gotten because of your fellow Canadian.

I want to return to the question of stability of buoyancy aids in
folding kayaks.  And then I am going to leave it because no one seems to
be applying any real science here other than general, unspecified
references to Archimedes.  What I have to say comes from observation,
which has to count for something.

Many years ago, long before the idea of doing anything with folding
kayaks ever even entered my mind, I observed what happened with folding
kayaks in two situations that I can only attribute to something to do
with the buoyancy aids inside their soft skins.  In the first one, I was
on a group paddling trip.  I was directly alongside a couple in a double
Klepper, when the fellow decided to stand up (he later said he wanted to
stretch his legs).  He wasn't very well coordinated and he tipped the
kayak over.  I was about 30 feet directly to the side of his Klepper and
all I saw was black bottom and keel strips including the ones on both
chines, i.e. the kayak was almost completely on its side.  He fell out
and the kayak righted itself.  The woman in the front had only paddled
once before and hadn't the faintest idea of what a bracing stroke
was...so it wasn't she that righted the kayak.  The kayak wound up right
side up with the woman having a stunned look on her face.  I am not sure
how another kayak, a non-buoyancy aided flexible skin one, would behave
in similar circumstances.

Another observation, again from my pre-evangelistic folding kayak days. 
I was paddling a double Klepper with my wife in our first months of
kayaking experience.  We went out through surf off of Brighton Beach in
NYC.  I was fiddling with a rudder lifter that I had added to the kayak
(they lacked them then and it was the first thing that I ever innovated
for the kayak that eventually got me interested in writing about this
particular species of kayaks) and did not pay heed to what was happening
with the waves coming in on us.  The kayak completely broached, so much
so that our kayaking friends on the beach with many years of kayaking
and kayaking teaching experience fully expected our Klepper to
windowshade all the way back to the beach.  It didn't.  While the wave
side of the kayak rose way up and we were well over, something kicked
in, without any bracing whatsoever by either of us...my wife didn't know
how to brace and both my hands were on my rudder lifter line.

Will folding kayaks flip?  Of course they can and do.  But it takes a
lot, and my observation tells me that the bouyancy aids inside are
kicking in at some point to some degree enough to say that the
phenomenon does exist.

ralph diaz 
-- 
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Ralph Diaz . . . Folding Kayaker newsletter
PO Box 0754, New York, NY 10024
Tel: 212-724-5069; E-mail: rdiaz_at_ix.netcom.com
"Where's your sea kayak?"----"It's in the bag."
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