Re: Stretching Existing Design 10% -- Frame Spacing?
--- Inbolger@yahoogroups.com, "pvanderwaart" <pvanderw@o...> wrote:
All of which is to say that is you increase the frame spacing, you
should also be increasing the thickness of the planking.
Unless of course you communicate with the designer and get his
approval. For ex. John Welsford says I can stretch Seagull or Joansa
10% but not his Light Dory.
Bruce Hector
Just cooling off in the a/c'ed office with a cool one as the glue
sets after I bonded on the bottom of the 10' 6" TIMS sharpie bow
unit. Nada mas for today, as I won't touch it now till full cure.
Just details from now on. Remove, countersink and fill screw holes,
screw on 2 by 4 keel and 2 by 2 outwales, tape inside seams, add
floatation boxes and paint. I'm aiming for a 31' TIMS trial lashup,
hopefully under power, by next weekend.
technically I wouldn't dispute what you say here. There are other
questions that could be raised. For example there are designs that
will not work merely being stretched, they require other adjustments.
What is the limit to stretching? With the scale of most of the boats
being discussed on this board most design criteria are answered by
"more or less" for example the "formula" works out to require 5/16"
plywood. Well most of us would use 1/4" and those of us more
conservative would use 3/8". In this case we chose a little light or a
little heavy. The designs are based on using standard material and I
would assume that Mr Bolger at least is attacking the problem
conservatively. The difference probably doesn't matter a twit. Would
adding a frame to a 110% stretch add anything except a lot of
heartburn? Probably not for the boats we are dealing with. If you were
lofting a boat you might as well add the frame but if it's a Bolger
box why bother.
BobChamberland
questions that could be raised. For example there are designs that
will not work merely being stretched, they require other adjustments.
What is the limit to stretching? With the scale of most of the boats
being discussed on this board most design criteria are answered by
"more or less" for example the "formula" works out to require 5/16"
plywood. Well most of us would use 1/4" and those of us more
conservative would use 3/8". In this case we chose a little light or a
little heavy. The designs are based on using standard material and I
would assume that Mr Bolger at least is attacking the problem
conservatively. The difference probably doesn't matter a twit. Would
adding a frame to a 110% stretch add anything except a lot of
heartburn? Probably not for the boats we are dealing with. If you were
lofting a boat you might as well add the frame but if it's a Bolger
box why bother.
BobChamberland
--- Inbolger@yahoogroups.com, "pvanderwaart" <pvanderw@o...> wrote:
> > Space the frames 110% of the original. (and good luck)
>
> Umm. I wonder. The number of frames needed for ply construction
> depends on the thickness of the planking and the spacing between
> longitudinals (chines, etc.). The designer works out the spacing so
> that the stretch of the panel when it deforms in sea is less than a
> set amount, usually 1% to 3%. It's all explain in, for example,
> Arthur Edmonds "Designing Power & Sail" providing you can follow the
> discussion through all the typos and editing errors. You could also
> use the tables in Teale's books.
>
> All of which is to say that is you increase the frame spacing, you
> should also be increasing the thickness of the planking.
>
> Peter
> Space the frames 110% of the original. (and good luck)Umm. I wonder. The number of frames needed for ply construction
depends on the thickness of the planking and the spacing between
longitudinals (chines, etc.). The designer works out the spacing so
that the stretch of the panel when it deforms in sea is less than a
set amount, usually 1% to 3%. It's all explain in, for example,
Arthur Edmonds "Designing Power & Sail" providing you can follow the
discussion through all the typos and editing errors. You could also
use the tables in Teale's books.
All of which is to say that is you increase the frame spacing, you
should also be increasing the thickness of the planking.
Peter
>When stretching a design 10% more than its original length, how doesUsually just split the difference among all frames. Old copies of
>one go about figuring the positions of the frames? Maybe a dumb
>question. Maybe as plain as the nose on my face, but I need to be
>edjumicated.
"Forest & Stream" often gave a table of offselts with a note on
spacing frames for the "14' version" or the "16' version" of various
sailing canoes.
--
Craig O'Donnell
Sinepuxent Ancestors & Boats
<http://freepages.genealogy.rootsweb.com/~fassitt/>
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The Cheap Pages <http://www2.friend.ly.net/~dadadata/>
Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
American Proas, the Bolger Boat Honor Roll,
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_________________________________
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-- Macintosh kinda guy
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Thanks, Bob. I figured it out after I posted. Sometimes looking at
plans and thinking tends to clutter the brain and one needs to get
out of one's head every now and then for a reality check. I
appreciate your reply.
BTW, how's that Bobcat of yours? Are you getting much opportunity to
sail her? I've been fortunate enough to get out 2 times a week for
several hours sailing since mid-May. When summer classes end next
week, I'm going to increase that to 3 or 4 before the fall semester
starts.
Regards,
Dennis
plans and thinking tends to clutter the brain and one needs to get
out of one's head every now and then for a reality check. I
appreciate your reply.
BTW, how's that Bobcat of yours? Are you getting much opportunity to
sail her? I've been fortunate enough to get out 2 times a week for
several hours sailing since mid-May. When summer classes end next
week, I'm going to increase that to 3 or 4 before the fall semester
starts.
Regards,
Dennis
Hi Dennis,
Space the frames 110% of the original. (and good luck)
Bob Chamberland
Space the frames 110% of the original. (and good luck)
Bob Chamberland
--- Inbolger@yahoogroups.com, "Dennis Marshall" <PseudoDion3@a...> wrote:
> Alright, this has probably been covered here before, but the board is
> so chock full of posts I figured I would get a quicker answer than
> clawing my way through the archives.
>
> When stretching a design 10% more than its original length, how does
> one go about figuring the positions of the frames? Maybe a dumb
> question. Maybe as plain as the nose on my face, but I need to be
> edjumicated.
>
> Thanks,
>
> Dennis
Alright, this has probably been covered here before, but the board is
so chock full of posts I figured I would get a quicker answer than
clawing my way through the archives.
When stretching a design 10% more than its original length, how does
one go about figuring the positions of the frames? Maybe a dumb
question. Maybe as plain as the nose on my face, but I need to be
edjumicated.
Thanks,
Dennis
so chock full of posts I figured I would get a quicker answer than
clawing my way through the archives.
When stretching a design 10% more than its original length, how does
one go about figuring the positions of the frames? Maybe a dumb
question. Maybe as plain as the nose on my face, but I need to be
edjumicated.
Thanks,
Dennis