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ZeroLengthCurve  
#1 Posted : Wednesday, June 24, 2009 6:14:51 PM(UTC)
ZeroLengthCurve

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I am a member of a naval ship design forum:

http://warships1discussionboard...-Incident-II.html?page=3

Some of the guys there are brainiacs/wizards with making spreadsheets of weapons systems, hull displacement, and more in their notional plans. But, i'm suggesting to some of them they give Delftship a look for initial hull/hydros, and then exporting that file to .dxf and importing into ViaCAD.

Some probably use Rhino, if they are in the marine engineering field or just know about Rhino. But, as powerful as R is, it's not really a drafting tool, as far as i understand. I doubt that ANY of them use ShipConstructor, as it sits on top of full AutoCAD ($4k+), and SC itself runs maybe $3K or $26k for many modules used in team-oriented ship design and fab preparation.

If any of you have been hankering to get your feet wet with naval ship hulls, you should download the .iges file of the DTMB (David Taylor Model Basin)/Carderock model 5415, the 1980s design of the USS Arleigh Burke (DDG-51) hull.

http://www.iihr.uiowa.edu/gothe...rg2000/5415/5415_g&c.htm
http://www.iihr.uiowa.edu/gothe...rg2000/5415/5415_l&r.htm
http://www.simman2008.dk/5415/5415_test_program.htm


It's internationally well known among naval architects/engineers, naval arch students, and model enthusiasts. I myself only downloaded it a few weeks ago, having found about it serendipitously. Had i been into ViaCAD in 2005 or 2006, and had i found 5414, i could have had more motivation to stick to my hobby.

(I set myself back because DesignCAD 2D/3D on my floppies was utterly useless, i was running Win98 in Win4Lin in Linux, and my laptop was dead/dying and my desktops offered no benefits either. I only bought ViaCAD on a lark, since i was spending $100 on TurboCAD Deluxe 12/14 and CompUSA was closing, and VC 2D/3D was on the shelf for 3 weeks that i let go by after first noticing...).

Sufficiently enhanced, ViaCAD could find itself being used by many dilettante ship designers... Now, if only we can get our hands on 3D blocks of positional/manipulable shapes. I'd like to find a 3D human model that is not 2D posing as 3D, hehehe, with a foot base that i can just click and spin, and see all the realistic silhouette as i orbit/rotate my model.
jol  
#2 Posted : Thursday, June 25, 2009 8:44:35 AM(UTC)
jol

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At Bakewell-White we always used Maxsurf for hull generation - which everybody seemed to be very happy with. Nice and easy to use - and didn't attempt to do too much !

I'd certainly never attempt a hull in Shark or VC .. it's just not the right tool

As for the rest of the boat/yacht/ship, Shark - or Concepts as it was then was good - but provided many challenges as the maturity of the drawing and surfacing elements particularly had some way to go

It'd be much easier now - that was five years or so ago

.. and once the fantasmaglorical V6 is out .. well workflow will be vastly improved and most of the annoying drawing side and surface side issues will be eliminated - forever .. rendering will be pucka ! .. and history will be solid as a rock !

Right Tim ?

.. Tim ?

Attached examples were built - inside and out - in Concepts (now Shark) .. and Rendered in SharkFX. However, the hulls were always built in Maxsurf
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Steve.M  
#3 Posted : Thursday, June 25, 2009 11:08:58 AM(UTC)
Steve.M

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Originally Posted by: jol Go to Quoted Post
.. and once the fantasmaglorical V6 is out .. well workflow will be vastly improved and most of the annoying drawing side and surface side issues will be eliminated - forever .. rendering will be pucka ! .. and history will be solid as a rock !
I was going to ask if you have inside info, but then realized with
Originally Posted by: jol Go to Quoted Post

Right Tim ?

.. Tim ?
that is was more of an hope.

Not just a dig from me, but more of a personal hope that issues will be resolved.

- Steve
ZeroLengthCurve  
#4 Posted : Thursday, June 25, 2009 11:47:02 AM(UTC)
ZeroLengthCurve

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Short version:

I have a long road ahead toward becoming efficient to overcome my deficiencies...


Long version:

I got to play with a Rhino-based cross section of a container ship (the section being about 40' long, some 80' high and beam of about 100' i guess, with longitudinals, transverses, etc.) and it contained hundreds of layers. I cannot share it as it's company work, but while the .dxf output opened up in VC 6Pro in about 20 seconds and the numerous layers all were green, the Rhino extension of the file was taking so long i killed the process. VCP was iterating or doing something 1/2,000 on and on, but at like 15 or was it 149, i stopped it. That same file, opened natively in Rhino, however, opened up like lightening. The drafter who made the model is a wizard... a HELLUVA lot better than i am or should be.

I have no plans to use Sketch-up, but what i really would like -- which would help my use of VCP -- is the ability to say draw or extrude shapes/plate and then intersect one with another that may be smaller, say intersecting a girder and longitudinal or transverse stiffener and designating what solid is lopped off as soon as i click "accept location and trim assignment" or whatever terminology would be on a button.

Currently, (from Delftship) i have my stations (14 of them) and i also imported more (a total of like 562 port/562 stbd) and use the stations-feet as aids to draw ruled surfaces as the side shell. But, since i cannot join some surfaces (bad geometry/acis error/etc) i cannot always get a full-length section of surface with which to trim off excess plate the is outside the hull. (IIRC, in Sketchup if one overlaps two surfaces or solids they automagically dispose of the designated unwanted side... somebody refresh me on this...) I need to try grouping the surfaces to see if they'll act as one for purposes of trimming "green" or excess material outside the sideshell.

One thing i wish CAD programs would stop doing is imposing that surfaces need to be ONE and unless they are ONE they cannot collectively mathematically be used for cutting an intersecting solid. It's just way too much work/extra steps. Sort of like sawing: sometimes you use a table saw and guides, but other times just hacking of a perforated end is plenty good.

Right now, my inefficient initial step is to use a local area surface as the deck/platform, bounded by the two main transverse bulkheads, and the two sideshells. The surfaces are not contiguous, so ACIS error messages pop up and the contiguous deck surface cannot be trimmed in incremental steps. Maybe i'll have to just one by one draw or extrude deck from every so many stations-feet (and try to do it associatively? wait, no, if i turn off sideshell, then the deck would turn off, too...), since for *my* purposes, since this ship is not going to manufacture, i can live with millimeter gaps. However, my drafting supervisor admonishes me that even for my hobby, I should design it ACCURATELY...
ZeroLengthCurve  
#5 Posted : Thursday, June 25, 2009 1:46:44 PM(UTC)
ZeroLengthCurve

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Before i even *think* of rendering packages (Shark or otherwise, whether free or inexpensive) i have to organize my drawings such that i don't end up with files over 40 MB. Given my current RAM, graphics & CPU, I can tolerate opens taking 30 seconds and saves taking a minute, since it's my hobby.

For now, i'm going to just use the main file to do the sideshell as surfaces, but use solids for the decks and transverse bulkheads, then delete the related surfaces. Eventually, i'll delete some 1,100 lines that are actually "stations" running fore to aft. Those alone contribute over 5MB to the file size. Now, if only VC generated (or, if only i figure out how to make VC make) surfaces that are as small as the .iges file for the 5415 model of the DDG-51, my file sizes could be vastly smaller. Is it because the product that generated the 5415 is some super-duper expensive app with power and time to compress the heck out of the file and remove 95% of the nodes and lines? Maybe i can use VC to "resurface" my surfaces to achieve a similar effect?
ZeroLengthCurve  
#6 Posted : Thursday, June 25, 2009 3:04:59 PM(UTC)
ZeroLengthCurve

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I left in place the deck surface, starboard side shell, frames, stations, and the forward transverse bulkhead at frames 326 and 422.

If yo want to reproduce the transverse bulkheads the way i did:

-- ruled surface, at Fr/Station 326 and the line at the closest Station for port and for starboard.

-- ruled surface on the after line if the two, from port to starboard. the surface generates/sweeps up along the extents of the curves. Do the same for the forward line.

-- ruled surface on top of the two surfaces, using not lines, but the surface edge to create the top of the bulkhead

-- Stitch the 5 surfaces


if you want to, verify properties and assigned mild steel or something with a density of 516.6720 lbs/ft3 (or, if you prefer kg/m3, 8276.29151)


My dillemma is that the surfaces i create at the ft-stations/stations-feet curves don't always join. Even when they do, each successive join takes longer and longer to complete. Then, to mirror them to arrive at a contained structure takes more time.

Later, i'll want to sweep in some longitudinals and transverses, and it would be ideal if i use L stiffeners swept along a curve, maintaining an assigned height above the plate, and terminating just shy of the fore and aft bulkheads, with an angle cut to the ends.

But, for now, i need that deck plate to automagically follow the curve of the hull.

It would be stellar if VC could interpolate or interpret that the stations --if given surface-- would be the intersection point for the surfaces, and that a thickened plated that is thrown in the direction of up or of down should remain associated to the skin surface of the sideshell.

I gave in to joining each line segment, but that in this case is, well, over 60 segments just for port and starboard, and unfortunately, at the area of the sideshell and bulkhead, VC took to curving the lines rather than joining the up. That would create a surface larger than the intended containing boundaries. Fortunately, the TVBHD (transverse bulkheads) are surfaces and solids of easier construction, so only single lines resulted.

Now, some of you wondering why or advising me about tools to arrive at volumes... here's why i don't want to get into making and destroying solids: Later, that side shell will have at 3 or 4 foot intervals a number of sideshell stiffeners, or L-shaped girders running from top down. I may draw them continuous (not correct, nor ideal) or break them up every deck with 6 inches of spacing between deck and flange and overhead and flange. They are easy enough to create using the sweep tool. I'll make them solids. Those solids should be detectable inside the measured volume (fuel, potable water, fresh water, lube oil, whatever, doesn't matter what is in the tank. I'm not doing fuel density/cost/combustibility calcs, just volume for seawater, and later i can compensate for water type, temperature, etc, or leave that for naval buffs to drool over...) and then be subtracted from the measured volume.

So, it would be even stellarly fantastic if VC could detect the boundaries of dissimilar, intruding or penetrating objects and internally do the boundary cut and spare the user of drawing in inaccurate geometry and possibly forgetting to remove it from the model.

Of course, asking for this could help more than just me. Civil engineers might want to calculate water pressure/static head on a fuel or tank spill containment at a rail yard or airport or power station . If they draw in tank tower of say 30 feet and a given diameter, they might want to QUICKLY know the volume of that tank and how big a concentric barrier to design. Experts probably can do that on the back of an envelope... i wouldn't attempt it, hehehe. But, not having to draw a solid, not having to shell it, not having to balloon the model, not having to .... well, such things are wonderful to have as reality...

Anyway, you can see that the model is ~7.5MB (AND FAILS to upload...)... JUST for this much content...

DAMMIT, the 4.2MB file won't even upload... Have to settle on a jpg...
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ZeroLengthCurve  
#7 Posted : Friday, June 26, 2009 3:01:21 PM(UTC)
ZeroLengthCurve

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WELL... I think i have found a workaround to my personal dilemma....

In my long-winded writings above, i indicated i will remove the deck i drew as a large surface that i could not trim by groups or single segments of the sideshell.

My solution is to leave the plate in place, but then offset at distances equal to the width of the sideshell plating copies of a surface that will be trimming surfaces (yes, i can use infinite planes, but i haven't yet wrapped my head around them, and it's useful for my mind to actually see the location of the cutting surfaces since i can color them ad-hoc to monitor my steps.

The nice thing is that i may play around with joining the individual surfaces, that is sideshell 326.052 port to deck plate 326.052 to sideshell 326.052 starboard. Later i will cut holes for ladderways, deck drains, fuel lines and other penetrations as needed.

This is challenging, but it MAKES my brain LOOK for a solution. Hopefully i can apply this skill-growth to my day job and get more hours doing drafting in 3D in addition to 2D...
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