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From: Matt Broze <mkayaks_at_oz.net>
subject: Re: [Paddlewise] Pro's and Con's of the "Swede Form"
Date: Fri, 21 May 1999 23:27:46 -0700
Well I'm not named John so this may not be "the gospel" but this subject is
also pet pieve of mine so you sucked me in to giving a response.
The Swede-form shape (greater underwater volume aft of the midpoint) has
less resistance moving at the water's surface than either a fish-form shape
(its opposite) or a symmetrical hull. The finer bow more gently parts the
water for less wave-making resistance. The longer run of positive pressure
in the forebody also can result in a longer area of the hull being in
laminar flow (laminar flow over a surface creates about four times less drag
than turbulent flow).
Note: A fish-form shape has less resistance underwater or in the air (where
there is no wave drag). This has confused some designers who have consulted
hydrodynamic texts, but not gotten the full picture of what happens at the
water’s surface. Fast ships, canoes and kayaks are Swede-form. Fast
submarines and fast fish are fish-form.)

For a kayak a Swede-form hull has many other advantages over fish-form. They
include:
1)Less pounding in head seas because they are narrower in the area where
pounding occurs (but, bottom shape is a bigger factor in pounding so some
V-bottomed fishforms will be softer than a flat bottomed Swedeform shape),
2)Easier and quicker turning (turns are enhanced by the greater curve to the
stern--and leaning makes this effect even more pronounced),
3)Less weatherhelm (more windage and a longer lever arm in front of the
paddler and less behind)
4)More of its volume is usable storage space behind the paddler and less of
the volume is in the wasted space around the legs.
5)A narrower beam where the paddle enters the water means easier more
efficient paddling (less boat to reach over) and less turning moment
produced with each (less off-center) stroke.

Fishform advocates correctly point out that Swedeform is less directionally
stable (other things being equal). One of them used to even say fish-form
was self-correcting (when he really meant self-stabilizing).  I see this as
a disadvantage in a kayak. Directional stability just means you work harder
for each degree you turn rather than being able to translate momentum into
turning by leaning. Course keeping is actually harder with fish-form because
correcting your course after a wave has altered it is more difficult with a
kayak that resists turning. Fishform will be harder to turn and leaning
doesn't help turning nearly as much as with Swedeform. The less
directionally stable Swedeform shape will track just fine if some keel is
added in the rear, but when leaned it will still retain its superior turning
ability. The best of both, tracks straight and turns readily with a slight
lean.

As far as choosing a kayak goes, trying to figure out what is going to be
best for you intellectually is a hopeless task, you will just get bogged
down in controversy and verbiage. Paddle kayaks that are recommended to you,
and designed for what you want to do. You will feel what you like. Few can
translate the verbiage,  dimensions or even the shape of a kayak into the
"feel" that will result so why not go straight for the feel.
Matt Broze
www.marinerkayaks.com


-----Original Message-----
From: Hal Christiansen <hal_at_mbox305.swipnet.se>
To: PaddleWise (E-mail) <PaddleWise_at_lists.intelenet.net>
Date: Friday, May 21, 1999 2:55 PM
Subject: [Paddlewise] Pro's and Con's of the "Swede Form"


>As previously mentioned I am in the process of selecting my first kayak.
>
>I am hoping to entice several of you more experienced paddlers to
>'wax philosophical' on the pro's and con's of the Swede form boats.
>
>
>THANKS
>-Hal
>
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