Copenhagen ship curves in DXF or DWG?

JP Sipponen

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Mar 21, 2005, 12:14:40 PM3/21/05

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Do you know a site where these curves can be downloaded? I think they are no
more copyrighted?
http://www.macnaughtongroup.com/copenhagen_ships_curves.htm

Jukkis

Brian D

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Mar 21, 2005, 5:32:49 PM3/21/05

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If you find a source for the dwgs, please post here! I'm interested also.

Thx,
Brian D

"JP Sipponen" <so...@otapoisjippii.fi> wrote in message
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JP Sipponen

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Mar 22, 2005, 1:17:20 AM3/22/05

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> What would you need them for? Their purpose is for fairing a curve and
when
> you are working with a CAD program the B-spline function takes their place
> and does a much better job of it..

Old friend of mine with no computer makes boats and he needs a set of them.
They cost over 350 $ so I thought i would make them with a CNC router.

Jukkis

Glenn Ashmore

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Mar 21, 2005, 11:43:42 PM3/21/05

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What would you need them for? Their purpose is for fairing a curve and when
you are working with a CAD program the B-spline function takes their place
and does a much better job of it..

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Brian D" <briand...@comcNSastNS.neNSt> wrote in message
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per.c...@privat.dk

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Mar 22, 2005, 5:41:55 PM3/22/05

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Hi
Exchouse me, but what to use these for except spending the money, realy
the graphics look like a scan from an old book do anyone acturly pay
for such ,except as antikes ?

Mean such curves is a build-in and acturly more accurate curves, in any
decent CAD program.

Brian D

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Mar 22, 2005, 1:15:57 PM3/22/05

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Glenn,

You're a great contributor around here and your project all by itself is a
great inspiration. The same goes for your workmanship and all the items
you've made for your boat, so don't take this wrong. My statements below
are direct because I'm about as eloquent as a runaway freight train, but
they are not personal barbs by any means, just points of information to
consider ...made so that others won't go off with incorrect definitions:

1. NURBS are not 'conic sections'. Conic sections include the family of
curves obtained by slicing a cone with a plane (circles, ellipses,
hyperbolas, parabolas, straight lines, and single points). If you constrain
a NURB to being a quadratic in 2 dimensions (n=2, k=3), then the math
produces a conic section. NURBS are far more flexible than that. Good 2D
and 3D CAD software contains options to do just this, e.g. produce
'developable surfaces' or 'conic section curves'.

2. The Copenhagen curves are special in that they hold a special place in
history. Many feel that this particular set of curves (with monotonically
increasing curl from their inflection points) are the only curves, singly or
together, that produce certain classic lines ...sheer lines, stem lines,
etcetera. Whether everybody shares that opinion or not, there *is* value in
having these curves in DWG or DXF format as a set of references that can be
used when producing boat designs with CAD ...if you share this value
statement and desire to produce 'classic Copenhagen' lines on a boat. I own
a set myself but have not taken the time to produce them in CAD. I may
someday ...if I ever run out of things to do.

Brian D

"Glenn Ashmore" <gash...@cox.net> wrote in message
news:VJU%d.70764$SF.41768@lakeread08...
> In that case, you could download that picture, import it into Autocad,
> scale
> it and trace the patterns. For refference, I have a set of 8 curves and
> #43
> is 24" long and #59 is 12.5" long.
>
> Should be fairly easy to trace because, unlike French Curves they are made
> up of conic sections which is exactly what the non-uniform B-spline
> algorythm does.

>
> --
> Glenn Ashmore
>
> I'm building a 45' cutter in strip/composite. Watch my progress (or lack
> there of) at: http://www.rutuonline.com
> Shameless Commercial Division: http://www.spade-anchor-us.com
>

> "JP Sipponen" <so...@otapoisjippii.fi> wrote in message

> news:g6P%d.1638$es2...@reader1.news.jippii.net...

per.c...@privat.dk

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Mar 22, 2005, 7:54:13 AM3/22/05

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Hi
IThen what shuld be the trouble inserting the image into a CAD program
scale it and digitize it ?

Glenn Ashmore

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Mar 22, 2005, 8:04:57 AM3/22/05

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In that case, you could download that picture, import it into Autocad, scale
it and trace the patterns. For refference, I have a set of 8 curves and #43
is 24" long and #59 is 12.5" long.

Should be fairly easy to trace because, unlike French Curves they are made
up of conic sections which is exactly what the non-uniform B-spline
algorythm does.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"JP Sipponen" <so...@otapoisjippii.fi> wrote in message
news:g6P%d.1638$es2...@reader1.news.jippii.net...

JP Sipponen

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Mar 22, 2005, 9:18:20 AM3/22/05

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> In that case, you could download that picture, import it into Autocad,
scale
> it and trace the patterns. For refference, I have a set of 8 curves and
#43
> is 24" long and #59 is 12.5" long.
>
> Should be fairly easy to trace because, unlike French Curves they are made
> up of conic sections which is exactly what the non-uniform B-spline
> algorythm does.

http://www.macnaughtongroup.com/copenhagen_ships_curves.htm

Hmm... Yes... I have only AutoCad LT. Maybe the tracing could be done also
with CorelDraw and the curves then be imported into AutoCad LT. The quality
of the picture is a bit poor so I hope it does not need lots of rendering.
Never tried that tool... Thanks...

Jukkis

Evan Gatehouse

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Mar 23, 2005, 4:46:11 AM3/23/05

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Skene's Element's of Yacht Design has a much better picture of the
most commonly used of the Copenhagen curves. Scan it, import into
Autocad and trace over the TIF or similar raster image with some splines.

Evan Gatehouse

per.c...@privat.dk

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Mar 23, 2005, 7:13:22 AM3/23/05

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Hi

Brian D : "Good 2D

and 3D CAD software contains options to do just this, e.g. produce
'developable surfaces' or 'conic section curves'. "

Exactly but please don't forget that with the same computer
"'developable surfaces'" are not restricted to be shaped as slices of
"known geometrics".
I know many have bad experiment with socalled unfolding software but
realy most bad shapes come from free-download limited software , that
can only produce a very rough unfolding ----- fact is that with just a
bit effort you can "unfold" reasoable tight poly mesh , the limitations
most often is in the number of faces allowed by the CAD program a
limitation you can overcome with external files ------ so surely
unfolding are tradisionaly done from "known geometrics" but realy you
don't need to buckle a troubled assembly of cylinders and cone slices
,fact is that you can unfold computer meshes, you don't need to "build
with known geometrics just to unfold.