PaddleWise by thread

From: <Rcgibbert_at_aol.com>
subject: Re: [Paddlewise] [PaddleWise] Skin on Frame Boats...the dead and the un-dead!
Date: Thu, 23 Sep 2004 12:24:10 EDT
In a message dated 9/22/2004 6:38:00 PM Pacific Daylight Time, 
pac_at_premier1.net writes:


> as I wrote, it uses less materials and is generally weighs about half as 
> much
> as production hard shells, it takes much less labor to build by hand, it 
> cost
> very little in materials, and it allows some flex in the hull which can have
> advantages in rough water.  BTW I meant to write that SOF does NOT lend it
> self to production very well because of the amount of hand labor involved.
> 

I thought this would get to the opinion stage of what is better for what ever 
reasons. One can build a boat in glass, wood strip or plywood and decide 
their way is right for themselves and others, but the superior thing is overboard. 
I know SOF only paddlers, more skilled AND better looking than I, that agree 
with you. But it is still an opinion. Hardshell only paddlers have as many and 
varied reasons for creating a case of superiority for their chosen craft.

> 
> >How does an SOF PERFORM better than a hard-shell by virtue of its
> construction process?
> 
> Become of the flex of the skin and frame, there are conditions that it is 
> more
> controllable.  A SOF hull feels "alive" around you, like the flex of a ski
> boot, or the suspension on a car.  A hard shell feels "dead".  My 
> obersvation
> after doing side by side comparison in the same conditions.

As a dedicated paddler to both hardshells and SOF I can argue that the 
undulating, snaky, slinky ride of an SOF has its detractors for that very reason. 
They or we have no control issues in rough water because of the hardshell, in 
fact turning on the top of swells or waves is easier as the hull doesn't try to 
conform to it. Yours or my observations are still opinions, not facts.


> 
> >Could I replicate an outstanding SOF design in glass and make it perform as
> well?
> 
> IT has been tried and they most definitely DO NOT perform the same.  The 
> flex
> makes a big difference.

Great point from both you and Matt. 

> 
> >If I then added bulkheads and hatches, (to reduce foldable volume), could I
> then argue it was safer?


I meant floodable volume, sorry.

> 
> I have done this on a SOF, you have to get creative with the bulkhead to 
> still
> allow flex in the skin/hull but still have it water tight.  the only bad 
> thing
> beside the extra work, was the extra weight (about 5 lb.).  But is still 
> acted
> like an SOF, not a "dead" hard shell.

"Dead" is so dramatic, or is that undramatic? I notice when waves grow, how 
un-dead people become due to their twitchiness in hardshells. You can observe 
it in the waist and foredeck, or minimal range in side to side movement. Lots 
of folks come alive in that environment, though, and seek it out as often as 
possible.That is a specific example of how hardshells are the un-dead. So, can 
we stop with the superiority thing?

Rob G
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************
From: Tom Yost <tom_yost_at_msn.com>
subject: Re: [Paddlewise] [PaddleWise] Skin on Frame Boats...the dead and the un-dead!
Date: Thu, 23 Sep 2004 11:37:58 -0600
When I built my first stripper many years ago, I was convinced that there was
nothing finer on the water.  Over the years, and nearly 30 homebuilt boats
later ( wood  SOF, aluminum SOF, woodstrip, S&G, and aluminum SOF folders), I
am now convinced that they all are great boats.  They just have different
characteristics, but I cannot in my own mind, say that any one type is
superior.

The more you build, the more open you become to the idea that different type
kayaks have many more similarities than differences.

Tom
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************
From: Matt Broze <mkayaks_at_oz.net>
subject: Re: [Paddlewise] [PaddleWise] Skin on Frame Boats...the dead and the un-dead!
Date: Fri, 24 Sep 2004 17:40:59 -0700
Mike Daly wrote:

>>>>>>>On 23 Sep 2004 at 8:36, Gordin Warner wrote:

> If the theory is correct a SOF kayak should enjoy a positive gain from
> the indentations along the hull.  I suppose the size of the
> indentations might have a negative affect on this.

The size is critical.  It is also related to the velocity of the
fluid along the surface.  Golf balls have small dimples and move
quite fast.  SOF kayaks have relatively smooth changes over a large
scale and move slowly in the water.

I doubt that the shape changes in the SOF have a significant effect
on the flow.

BTW, aircraft floats operate by planing, not displacement (well, as
you get anywhere near take off speed), so I doubt the analogy is
completely correct.<<<<<

I couldn't agree more. Dimples on a golf ball work by delaying separation of
the airflow around the back of the ball so that it doesn't have as big of a
"wake" retarding it. They are only effective in a certain range of
Reynolds's numbers (a relationship between the speed the length effected and
the density of the fluid). If I recall correctly, when the Reynolds's number
is the same, even though the other parameters making it up are all
different, things work the same. Kayaks operate in a different range than
golf balls. Also, not being blunt on the rear like a ball a kayak would not
likely benefit much from the delayed separation due to dimples even if it
did happen operate in the same Reynolds's number range.

Choppy water lets a planing hull skip from wave top to wave top cutting
friction, unfortunately for the theory, kayaks aren't fast enough to gain
this advantage from chop except maybe when surfing down the face of a steep
wave.

Peter used the word "dead" to describe the rigor mortis of "stiff" kayaks
compared to the squishy movement of a SOF in waves. wouldn't that make a
partially inflated rubber ducky the ultimate in undeadness? I too often
think some kayaks feel "dead", but having a much large base to compare from
(I'm almost to 800 now) I have come to somewhat different conclusions than
Peter as to the causes of a "dead" feel. To me things that contribute to a
dead feel are: heavy weight (gear loads and heavy kayaks suffering from
inertia), flexible kayaks (some of my energy is wasted flexing the
kayak--rotomolded plastic, flexible SOF, and inflatables come to mind), too
much friction holding them back (kayaks that are too wide, too long, or
poorly shaped), too hard to turn (stiff tracking kayaks with lots of keel at
the bow and stern don't feel lively to me, those responsive to body English
and paddle strokes do). Therefore, a stiff light carbon or wood kayak with a
sporty and responsive feel paddled empty would be my first choice. A stiff
SOF can be pretty good too but that floating dead cat flex of a soft one
would be a negative rather than a positive. The softer the flex the deader
it will feel. Think partially inflated inflatable or a dead jellyfish for
the extreme. Things that are alive counteract the forces acting on them. A
paddler is alive, a rigid kayak is moved by outside forces, does not
actively resist them, but is also not changed in shape by them. A flexible
kayak is like a dead animal that changes it shape when acted upon by other
forces in the environment, including the living paddler. It tends to absorb
those forces and dissipate them by flexing.

Matt Broze
www.marinerkayaks.com
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************
From: alex <al.m_at_3web.net>
subject: Re: [Paddlewise] [PaddleWise] Skin on Frame Boats...the dead and the un-dead!
Date: Fri, 24 Sep 2004 19:54:23 -0700
> To me things that contribute to a
> dead feel are: heavy weight (gear loads and heavy kayaks suffering from
> inertia), flexible kayaks (some of my energy is wasted flexing the
> kayak--rotomolded plastic, flexible SOF, and inflatables come to mind),
too
> much friction holding them back (kayaks that are too wide, too long, or
> poorly shaped), too hard to turn (stiff tracking kayaks with lots of keel
at
> the bow and stern don't feel lively to me, those responsive to body
English
> and paddle strokes do).
/skip/
> A flexible
> kayak is like a dead animal that changes it shape when acted upon by other
> forces in the environment, including the living paddler. It tends to
absorb
> those forces and dissipate them by flexing.

That's what I meant.  Folding kayaks come to my mind as well (often too wide
and irresponsive as well).  Too much of flex, compared to non-foldable SOF.
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************

This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:39 PDT