Hull design software
carl...@ucbeh.san.uc.edu
that will generate the shape of hull panels from offset plans? I am attempting
to adapt the plans from Davis Alford's Tursiops kayak to a skin on frame boat,
and would be assisted in this by being able to preview the desired hull shape.
While I am aware that there are many commercial boat design CAD packages
available, my application is so limited that I cannot justify the investment in
one. Thanks in advance for any assistance rendered.
Steve C.
usisired
CRring
I too am interested in c.a.d programs. But I have alot more experience
with
boatbuilding than with computers.
I am willing to bet, for a simple project such as yours, it would be
quicker,
and certainly cheaper to build a scale model than to learn one of these
programs.
Also, the model would be a thing of beauty you can display in your home.
you can look at it from all angles, in different light, try paint
schemes, tank test
it, etc.
The trick is to use a scale which you can realisticly deal with and
build accurately. 1.5 inch to the foot is very workable. I have built
several to this scale
completely accurate, from a 15' sharpie of my own design ( which proved
to be
very successful- I built one for myself fullsize and one for a freind) to
a 21' cabin
sloop. The 21' sloop model is about 5' long and sails like a witch.
I would think skin over frame would be very easy to construct.
Basically, build
just as you would the real thing, a mold at each station. If you dont like
the shape, change a mold ( or stem, etc). Record your changes, and when
its right,
you have your model .and your new offsets etc. Problems in construction
become apparent quickly, and when you build the real thing it will go much
more
smoothly.
Joe Dominic
I understand your fear of computers and your belief that 'learning' a
hull design program is difficult. This is not necessarily so...
Like yourself, I too have tried many hull design packages....most have a
very steep learning curve and presume you know much more about design
than the average builder (particularly the recreational or back-yard
type). In many cases the user interface makes no sense at all. Menus
are not logically constructed, etc.
My partner and I have spent quite some time writing 'BtDzn' (,,,acronym
for BoatDesign..??). Considerable effort was put into making the pkg as
user friendly and easy to use as possible. If you try the shareware
version currently available (or even look through the slideshow demo) you
will see that the user is required only to manipulate the chine curve
shape, the program does the rest. It will create station (or any other
section) molds, develop the flat panels and expand them to the their flat
shape. You can print them out any scale, including a model scale, full
size, or even larger if you like.
The problem with designing a boat as you suggest, by building a model
first is really quite unnecessary, and is fraught with danger .. not to
mention time consuming by requiring so much trial and error (either
drafting or changing station molds, and trying to shape panels to fit
properly) work.
I have seen many times, models made this way when extrapolated to full size
just require so much additional work just to get the boat together that
the enjoyment one would otherwise get has been swallowed up by frustration.
I will conceed that if only a couple of molds are used and there is no
significant curvature in the hull, the chances of success increase.
Either way, I would not recommend this proceedure for anything but the
simplest of hulls...perhaps a flat-bottomed craft of sorts, but not much
else.
And as for taking offsets from say a 1/12th scale with the usual tools
(ruler!)...thats even more scary. I have built many models and quite a
few full size boats up to 30+ feet. Never would I attempt to mock up a
model and expect the full size hull to simply 'fit'.
I presume you have NOT looked at the demo, I suggest you do. If for
nothing else just to inform yourself that designing vessels need not be a
difficult or time consuming task.
BtDzn, besides doing all the drafting for you will also print out offsets
(in either metric or feet & decimal feet) and perform hydrostatics. At
least you will be better able to judge the quality and fitness of the
boat for a given purpose.
As a boatbuilder moreso than a c.a.d. tech I'd be very interested to hear
your comments...after you give 'BtDzn' a try. I think you'll be
impressed with the ease, speed, accuracy and general results. Besides,
if you have to spend 10 or more hours designing the model, etc. consider
your time worth $15 / hour. In those short hours you will have completely
spent the full cost of this version of BtDzn !
Again, please send or post your comments.
Merry Christmas,
Rgds,
-joe-
==BOATDESIGN-----------++++ 'BtDzn' ( 1994 ) ++++---------------BOATDESIGN==
Hard-Chine Hull Design for the PC. Surface development for multiple panels.
Cross-Section tools / Flat panel expansion / Hydrostatics / etc. Runs in
EasyCAD/FastCAD. BTDEMO.ZIP <slideshow> and BTDZNV1S.ZIP <full functioning
shareware> via FTP at 'ftp.compusult.nf.ca' in directory /pub/msdos/btdzn
-----------------------------<<<< TRY IT ! >>>>-----------------------------
Chris Ring
actually manipulate any lines. A drawback that became apparent right away
that I never thought of, and I', sure it exists in all but the biggest p.cs
is that looking at a 14"monitor it is impossible to judge the quality of the
lines. In a say,15' boat, ain my opinion, a variance of half an inch to the
sheer- even if fair- will change the character of the end result. The only
remedy would be to printout, judge, revise over and over till its right.
to me , its quicker and more satisfying to draw with pencil to a large scale,
(I like 1.5" to the foot, or even 3"on something small) and keep a big eraser
nearby.
I would still like to try the program though, I think it would be very useful
especially for hard-chined "quick-and-dirty" tape and stitch type construction
which I am interested in. I do prefer building in a more traditional manner
on a strongback with temp molds and there is no need for me to mathematicaly
expand any planking.
I have built a couple of Bolgers designs and was impressed how they went
together without any temp molds or even strongback (one was his 23'schooner
that really flies) they both used plank expansions as plans, with permanent
bulkheads
as molds. chris
Joe Dominic
Re...your post...
--> You cannot manipulate the 'lines' in the demo.
^^^^
==>> It is a slideshow of screen images only.
--> The drawback you perceive..."impossible to judge the quality of the
lines on a 14" monitor..<etc>"
==>> Actually Chris...'God forbid' that ANY hull design pkg.
require the user to visually 'judge' the quality and fairness of lines on
_any_ monitor !! 'BtDzn' curves are a special case of B-spline requiring 4
nodes..2 endpoints and 2 evenly spaced control nodes..this naturally
results in both a visually and mathematically fair curve, and therefore
surface (after passing the ruling test of course).
You say the program is useful for what you refer to as your
'quick-n-dirty' method of stitch'n tape construction..?? True it can be
used to create highly accurate printouts (or measurements) of hull
panels, section shapes (including all bhds, longitudinals, the strongback
you mention...basically 'any' hull cross-section....). The hydrostatics
are accurate to well within what is accepted in the industry, etc. In
fact you can also create and printout individual templates for individual
planks...the restrictions are mainly those of the designer. Perhaps if
you get an opportunity to see it going or use it yourself, you will
better understand what is going on.
Good luck...
Happy New Year !!
-jd-