Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
From: James Mitchell (mariner@seanet.com)
Date: Fri Dec 08 2000 - 00:20:44 EST
In observing the hulls in the museums in Southeast Alaska, I am always
impressed with the low depth of the hull from keel to gunwale. Their boats
were generally taller by a good three or four inches than most of ours
(their 16-18" height to the cockpit rims as opposed to our 12"), but even so
they are getting what appears to be about 6-8" from keel to top of gunwales.
I am having to estimate or scale this from drawings, for the most part, so
my numbers could be way off... but the bottom line for me is that they
placed their beam proportionally lower than most modern designs. I would
guess that if we scaled the King and Nunivak hulls from keel to top of the
deck, the gunwal would be at about 40% of that height as opposed to about
60% or more in a baidarka.
Consequently, their decks are very very steep. When I first observed this on
the King Island and Nunivak hulls, I immediately envisioned stubbing that
bow into a wave on a run downwind, and watching that bow literally cut its
way back to the surface for air -- much unlike our baidarkas, which reverse
those ratios. The finest example of this is the Cape Espenberg hull sitting
on the display case at Sheldon Jackson in Sitka.
Got some wood out back waiting for me to shun my nice warm house and get
back to work. Am planning both a single and a double with this lowered
gunwale. I expect more secondary stability, less windage, and a really fast
rebound in steep waves.
----- Original Message -----
From: "Douglas Ingram" <redcanoe@pangea.ca>
To: <baidarka@lists.intelenet.net>
Sent: Wednesday, December 06, 2000 7:51 AM
Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> James,
>
> You are quite welcome. Its not always that I am able to offer something
of
> relevant value to this list, not being a kayaker and all, but I am glad to
> do so when able.
>
> Deadrise affects that portion of the bottom from the keel to the chine.
> That point is fairly obvious on some boats, such as a Greeland kayak, but
> less so on "slack bilged" craft. One will have to make some decision
where
> the bottom is no longer the bottom and is no the side.
>
> Tumblehome is not the great bugaboo that some make it out to be, and
neither
> is flare the great panacea. Each must be used in balance given the design
> criteria. Same thing as primary and secondary stability, they must be in
> balance to give the paddler a continuous and predictable sense of the
boats
> stability curve. There have been boats that I have paddled where the
> balance has not been kept. The max width was near the waterline, and then
> there was a very tight curve into tumblehome to keep the gunnels narrow
for
> easy paddling. The combined effect resulted in a very hard chine and no
> reserve bouyancy. Any heeling over was like trying to balance on the edge
> of a cube. It was a teetertotter, one wiff the wrong way and BOOM, over
she
> goes! Many new canoe designs are incorporating soft bilges for easy
> predictable heeling, max width well above the waterline for effective
flare,
> and the a tight turn, or shoulder, about 3-4" below the gunnel, producing
> enough tumblehome where it is actually needed, for easy paddling.
>
> What tumblehome does do is this:
> -continuous curvature of the ribs provides a structure of greater
stiffness
> for its dimension.
> -reduces the width that the paddler must reach over in order to acheive a
> good stroke without banging their hands
> -makes a boat look sleeker due to narrower gunnel width
> -actually increases the depth of the boat while it is heeled over.
>
> That being said, one can actually have the effect of flare and tumblehome
in
> the same boat, as long as the max. width is above the waterline.
>
> It has been my observation that most kayaks have a narrow enough width
that
> tumblehome is not always necessary for issues of reach and hand banging
and
> that many kayaks have their gunnels low enough that the tumblehome is
built
> into the deck rather than the hull.
>
> Douglas
>
>
> > Thankyou for clarifying, Douglas! Does that mean that deadrise would
only
> > be appropriate when speaking of the angle to the first stringer? How
> would
> > you express deadrise on a round bottom sailboat? Just curious...
> >
> > You are absolutely right, expanding the gunwales on Raven would and did
> > increase rocker. This, of course, was not a problem on Raven (nor would
> it
> > be on most baidarkas) as the final straw that led to this surgery was
when
> I
> > got locked into a trough during a spring squall in Canada and could not
> turn
> > her downwind to save me. Literally. I also think the additional rocker
has
> > added greatly to her stability, helping accomplish the other goal of
this
> > rebuild. Heron was planned with this flare in her, so the rocker there
> was
> > not affected.
> >
> > Another aside: I have never understood any purpose to tumblehome.
Prijon
> > built that into some of their sea hulls, and I always found it a curious
> > design choice. The net effect would be an increase in primary stability
> but
> > with a marked decrease in secondary, as the additional heel would not
act
> to
> > shift the center of bouyancy farther outboard, as happens with flare.
The
> > result, and I have seen this with my own two eyes on a waterlogged
> > girlfriend, is to make the Prijon hull into one of the wettest surprises
> in
> > the business... ahh, this boat is sooo stable... ooops... glug glug.
> >
> > ----- Original Message -----
> > From: "Douglas Ingram" <redcanoe@pangea.ca>
> > To: <baidarka@lists.intelenet.net>
> > Sent: Tuesday, December 05, 2000 7:17 AM
> > Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> >
> >
> > > A few observations, if I may.
> > >
> > > Deadrise is the angle that the bottom of the boat establishes using
the
> > keel
> > > or centerline as the point of the angle, and a horizontal line, called
> the
> > > baseline. For example, a perfectly flat bottom boat has zero
deadrise.
> > >
> > > Flare is one term ( tumblehome and plumb being the others) used to
> > describe
> > > the angle that the sides make relative to a verticle line parallel to
> the
> > > centerline.
> > >
> > > It has been my observation, when working on canoes when the thwarts
are
> > > removed, that the sides want to spread outwards, therby increasing
> flare,
> > > and having comparatively little effect upon dearise.
> > >
> > > The increase in flare effected upon an already built structure is
> > coincident
> > > with an increase in curvature of the gunnels, that is, they are less
> > > straight. Now, as the gunnel is a fixed length, this increase in
> > curvature
> > > has the interesting effect of reducing the distance between the stems.
> > > While the difference will not dramatically affect the boats length, it
> is
> > > enough to significantly affect the amount of rocker. As the stems are
> > > pulled closer together, they are pulled up. If you need help to
> visualize
> > > this, use a letter envelope to simulate the boat.
> > >
> > > Douglas Ingram
> > >
> > > ----- Original Message -----
> > > From: James Mitchell <mariner@seanet.com>
> > > To: <baidarka@lists.intelenet.net>
> > > Sent: Monday, December 04, 2000 4:21 PM
> > > Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> > >
> > >
> > >
> > >
>
> > >
> > >
> > > > If I understand your terms correctly, I am talking about the angle
of
> > the
> > > > deadrise. You are correct about the "V" being decreased at the keel.
> > > > Because of the way I did this, the effect is proportionally larger
as
> > you
> > > > approach the gunwale; therefore there is very little impact on
> > waterline;
> > > > and even less impact on the angles at the keel. I haven't had a
chance
> > to
> > > > paddle in wind yet, and such would be a very subjective test anyway;
> > > > however, Heron and Orca have much the same flare/keel arrangement
and
> > > track
> > > > very well.
> > > >
> > > > I would guess that the tightness of the skin has more to do with
> > tracking
> > > > than the changes I made. Because of some unfortunate temperature and
> > > > humidity changes, Raven's skin came out looser than I wanted (hurray
> for
> > > > working outside). But one benefit of a loose skin is better
tracking,
> > > > because the keel and the stringers become more exposed as the skin
> wraps
> > > > around them.
> > > >
> > > > Incidentally, Raven, Orca, and Chinook are all for sale if anyone is
> > > > interested.
> > > >
> > > > ----- Original Message -----
> > > > From: "Native Ways" <nativeways@hotmail.com>
> > > > To: <baidarka@lists.intelenet.net>
> > > > Sent: Monday, December 04, 2000 1:54 PM
> > > > Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> > > >
> > > >
> > > > > James,
> > > > > When you peak of "flare" are you talking about the beam, or the
dead
> > > rise
> > > > > from the keel to the chine, making it more of a V hull? It sounds
> like
> > > you
> > > > > increased the beam on Raven at mid-ships but left the old ribs
as-is
> > > which
> > > > > would, I think, flatten the bottom a little, effectively making
less
> > > "V",
> > > > > and a shallower cock-pit area. No? How is tracking with a beam
wind
> > > > compared
> > > > > to before?
> > > > > Greg
> > > > >
> > > > >
> > > > > >From: "James Mitchell" <mariner@seanet.com>
> > > > > >Reply-To: baidarka@lists.intelenet.net
> > > > > >To: <baidarka@lists.intelenet.net>
> > > > > >Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> > > > > >Date: Sat, 2 Dec 2000 18:32:55 -0800
> > > > > >MIME-Version: 1.0
> > > > > >Received: from [207.38.45.9] by hotmail.com (3.2) with ESMTP id
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> > > (PST)
> > > > > >From owner-baidarka@ns1.intelenet.net Sat Dec 02 18:47:18 2000
> > > > > >Message-ID: <006e01c05cd1$58265000$c79c2640@hjdm2528>
> > > > > >References: <OE69qJfhUbfh9aKOMpZ00002180@hotmail.com>
> > > > > >X-Mailer: Microsoft Outlook Express 5.50.4133.2400
> > > > > >Sender: owner-baidarka@lists.intelenet.net
> > > > > >Precedence: list
> > > > > >
> > > > > >Yeah, I think flare has a lot more to do with the stability than
> does
> > > > width
> > > > > >per se. Since our discussion, I completed and tested Raven. I can
> now
> > > > hang
> > > > > >her on her gunwale and spin her; previously, I couldn't take my
> eyes
> > > off
> > > > > >the
> > > > > >water. This is the second hull I have done this too, the first
> being
> > > > Orca,
> > > > > >with same result. And Heron, which was designed from the
beginning
> > with
> > > > the
> > > > > >additional secondary flare, I have actually dosed off while
sitting
> > in
> > > > the
> > > > > >reeds at Spencer Island in the late afternoon summer sun. I
think
> > you
> > > > > >could
> > > > > >fish all day in that boat.
> > > > > >
> > > > > >----- Original Message -----
> > > > > >From: "Phil Sharp" <srelt@msn.com>
> > > > > >To: "BaidarkaSubmission" <baidarka@lists.intelenet.net>
> > > > > >Sent: Wednesday, November 29, 2000 5:22 PM
> > > > > >Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> > > > > >
> > > > > >
> > > > > > > Thanks for the idea James. I had not considered doing it that
> > way.
> > > I
> > > > > >had
> > > > > > > thought about increasing gunwale width, but then
proportionately
> > > > > >increasing
> > > > > > > the stringer width as well, and maybe adding one more
stringer
> > each
> > > > > >side
> > > > > >to
> > > > > > > support the added width. Your idea is intiguing, though.
Now,
> do
> > > you
> > > > > >do
> > > > > >any
> > > > > > > fishing from your kayak, and if not, do you think you could if
> you
> > > > > >wanted
> > > > > >to?
> > > > > > > Sorry it took me so long to get back to you; I have been out
of
> > > town.
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Phil Sharp
> > > > > > >
> > > > > > >
> > > > > > > SeaCaller
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > >
> > > > > > >
> > > > > > > From: James Mitchell
> > > > > > >
> > > > > > >
> > > > > > > Sent: Tuesday, November 21, 2000 9:39 PM
> > > > > > >
> > > > > > >
> > > > > > > To: baidarka@lists.intelenet.net
> > > > > > >
> > > > > > >
> > > > > > > Subject: Re: baidarka Date: Tue, 21 Nov 2000 17:58:26 -0800
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Phil, I recently modified my first hull to increase its
> stability.
> > > > > > >
> > > > > > >
> > > > > > > Originally it was 17'-2" x 20.5", now it is 17'-1.5" by
22.25".
> > All
> > > > the
> > > > > > >
> > > > > > >
> > > > > > > increase is at the gunwale. I replaced all the deck beams to
> > > increase
> > > > > >the
> > > > > > >
> > > > > > >
> > > > > > > width, moving the old ones forward a station (and retrimming
> > them).
> > > > > >Most
> > > > > > >
> > > > > > >
> > > > > > > had to be replaced.
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > The modification has worked very well. With no noticeable
> impact
> > on
> > > > > >speed,
> > > > > > >
> > > > > > >
> > > > > > > I have easily increased the effective stability nearly double
to
> > the
> > > > > >point
> > > > > > >
> > > > > > >
> > > > > > > where I can hang the hull on its gunwale clear above the
cockpit
> > > rim.
> > > > > > >
> > > > > > >
> > > > > > > Prior, if I tried that, it would have capsized. What I have
> > > confirmed
> > > > > >here
> > > > > > >
> > > > > > >
> > > > > > > is the impact of flare on the stability. I would encourage
you
> to
> > > > build
> > > > > >as
> > > > > > >
> > > > > > >
> > > > > > > much flare into your hull as possible. That way the stability
> will
> > > be
> > > > > >there
> > > > > > >
> > > > > > >
> > > > > > > when needed, but won't slow you down when you don't.
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > >
> > > > > > >
> > > > > > > From: "Phil Sharp" <srelt@msn.com>
> > > > > > >
> > > > > > >
> > > > > > > To: "BaidarkaSubmission" <baidarka@lists.intelenet.net>
> > > > > > >
> > > > > > >
> > > > > > > Sent: Wednesday, November 15, 2000 8:26 AM
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > Do any of you fish regularly from your Baidarkas? If so,
did
> > you
> > > > > >change
> > > > > > >
> > > > > > >
> > > > > > > the
> > > > > > >
> > > > > > >
> > > > > > > > dimensions to make it more stable? What are those
> > > > dimensions--length,
> > > > > > >
> > > > > > >
> > > > > > > width?
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > Thanks.
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > SeaCaller
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > >
> > >
> >srelt@msn.com___________________________________________________________
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > Get more from your time online. FREE MSN Explorer download
:
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Baidarka Mailing List - All postings copyright the author and not to be
reproduced outside Baidarka or Baidarka archives without author's permission
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This archive was generated by hypermail 2b27 : Mon Jan 01 2001 - 01:00:02 EST