Easy way of creating frames and stringers?

DELFTship forum Hull modeling Easy way of creating frames and stringers?

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    • #35050
      Hampus Mattsson
      Participant

      Is there an easy way of creating frames and stringers? IE modelling the hull and then create the frames on the inside of the hull to fit exactly. Or do I have to create the frames and fit them manually?

      /Hampus

    • #35052
      Hrvoje
      Participant

      Hi, Hampus!
      I export the hull lines as “DXF 3D Polylines”. Then I open exported file in CAD program. Using CAD program I design all needed frames and longitudinal girders. It is time consuming work, but I am retired and I do wooden ship models for fun.
      Have a nice day!
      Dida

      Kind regards,

    • #35055
      MICHAEL KERR
      Participant

      Stations, waterlines, buttocks and control curves can all be exported into other CAD programs. Create your stations in Delft and export them as Dida said (DXF 3D polylines) your exported stations will appear as frames in your CAD Program but they have to be turned on in Delft and turn Precison up to Highest for export.

    • #35067
      Hampus Mattsson
      Participant

      Thank you for the replies. I found a way of doing it in Delftship. Probably not as accurate as exporting the stations though. I add a number of new points and put them carefully on a station. Then I create a face using the new points. The new side of the face has to be split a number of times. Then adjust the new points to fit, select all the edges of the new face and extrude curve as much as is needed to acheive the correct dimension of the frame. Seems to work quite well.

      /Hampus

    • #35071
      otaku
      Participant

      HiHampus,

      You may also want to do this:

      – Create stations at places where you want watertight bulkheads

      – Create stations at appropriate (if you go by Class rules for a given region/flagging) or convenient to you (fictional or notional designs) distances so that you later have them in place. Know that sometimes, either DS or your CAD program may “twist/kink” up some lines but you won’t know that until you try sweeping a line down a one-rail curve in your CAD app. Out of some 320 stations in my models, I sometimes have 3 or 4 stubborn, wanton, craze-inducing lines that don’t behave, and even regenerating them in the CAD app does no good. It sometimes takes convertion the line into another type.

      – Create two faces of the bhd by creating two stations where bulkheads exist, the distance being the plate thickness of the bhd. This could later help you to avoid certain trimming issues that might be specific to a particular CAD vendor

      – Create waterlines at locations of your deck plating — assuming you’re designing MODERN vessels in which “design for manufacture” is your rule, and thus your deck plating is horizontal, not sloped

      — Turn on the wls and stns

      — in Layers, create names for the watertight subdivisions (major watertight compartments) in your hull. Turn on meshes and assign them as convenient to you. This way, later in your CAD app, you can vastly more conveniently get out of the way any piece of the hull that is confounding your CAD activities as opposed to your (DS-based) HYDROS activities.

      As for the bhds, when you export them, and when you look at a profile in D/S, the bhds will be easier to locate by eye.

      Now, as for those meshes and waterlines, turn off the meshes. Now, select each waterline of interest, and CREASE that/those waterlines. What you end up with is plates or panels at each waterline and intersecting station. This might be nice if you assume you are designing a hull made of flat pieces rather than curved pieces. If designing a type of stealth ship, or just a very cheaply built ship, flat panels used extensively, as you probably guess, require probably no rolling, meaning all that attendant jiggery and press equipment is not part of the construction process, lowering some costs, probably significantly. But, that is beside the main benefit here:

      You can arrive at better weight estimation/calculations if your hull is more conveniently broken down in logical places. Why try to estimate weight of a compartment if the sideshell and decks and stringers in that compartment are running the full length of your DS model? Also, the stations then are pretty much already broken down by deck and waterline, meaning you can build sub-assemblies in CAD if that is your fancy. But, the pain in this is that rather than having a limited number of stations from gunwhale to center of keel at bottom, you have that times whatever number of waterlines you choose to crease, +/- other modified areas.

      Note: It can be quite time-consuming. The biggest most demoralizing part of doing it my way is that CAD and hydro vendors have very few if no two-way plugins, which otherwise could vastly speed up incremental changes or fixes when errors are discovered in finer-grained work within a CAD app. It is a major, major bummer that DS, Freeship/Hydronship, and ViaCAD and other CAD vendors don’t get together. If they did, a lot of vexing work could be streamlined, and poorer ship designers could avoid paying thousands of dollars per seat for CAD-design modules that they’ll hardly use regularly, but must pay for to get SOME utility out of the CAD app. (Imagine free-form designing the general hull in CAD, then importing to DS the various preliminary stuff, and assigning by layer the functions of those pieces and having the hydros further enhanced by the presence of those tiny little inclusions. Overall, it might not make much of a difference in this regard.)

      Hopefully, this is useful information.

    • #35083
      Hampus Mattsson
      Participant

      Thanks for that thourough description 🙂

    • #35085
      otaku
      Participant

      Thanks for that thourough description 🙂

      You’re welcome.

      Also, while in the layers area, consider color-coding your layers. Be sure to assign material mass/density information. If you are using Freeship/Hydronship AND DELFTship, be sure to note that they shift decimals differently than the other, and you could have wildly wrong density/weight results if you do not make the layer-by-layer changes. This may hamper or frustrate moving files back and forth. FS/HS also has a different idea about where the baseline is, as far as hydros calcs are concerned. Consequently, you’ll need to select your exported model and translate it vertically and do the same each time you import any supplemental/redundant layers — depending on your CAD app of choice. I use Punch! ViaCAD because it has very nice 3D design tools and a crisp, no-need-to-mode-switch 3D view. I hate and loathe the idea that if doing 3D work in a CAD app I must for some reason switch between drawing mode and “display” mode. ViaCAD shows my colors and surfaces and solids very beautifully, even if they are not engineering perfect.

      As far as layers go, compared to FS/HS, DelftShip has a very decidedly easier to use layer display and editing facility. It was a very nice change from its previous design. Martjin did a nice, heartwarming job of making things easier.

      As for creating stiffeners, since I’m using ViaCAD, this’ll be useful if you too are on ViaCAD or ViaCAD Pro, rather.

      — Import your stations into VCP.

      — Turn off any layers not needed

      — Create in the Stations layer two sublayers: one for stbd, one for port.

      — Assign as appropriate; repeat for waterlines and for other layers

      — Create layers according to how you work.

      In my case, after a couple or more years of experimenting (due to ViaCAD’s current inability to move layers out of their branches) I’ve decided to create master layers by compartment, then sublayers within by deck, then layers for sideshell stiffeners, stringers, girders, and longitudinals. Other layers are created as necessary, say for ventilation and so on. Some things demand to be completely on their own layer, so they are easy to manage than tracking down in deeply nested layers. Also, you may want to create construction layers within each compartment layer so that for visual reasons you can “declutter” your “picture” of your progress. It can be maddening to have unrelated construction lines and aiding surfaces in the way. But, one very, VERY nice feature of ViaCAD Pro is its cursor, named “LogiCursor”. When you attempt to select something, if it is coincident (by model orientation on screen) with some other geometry, a small “ambiguity” popup appears and presents to you the items which you can click on, and their geometry creation number in case you have multiple geometries/pieces same or similarly named.

      Another very VERY nice feature of VCP is that even while the other layers are turned off, you can use an assigned shortcut key to “unhide” other layers. Press your shortcut key, then, with the layers dialog box open, right click on a layer of interest, and then select “Select all items in this layer”, and HWALLAH! Those items appear. So, this again is a(nother) strong reason to create things by compartment in a subdivided model with the whole model in one file (if you have the RAM & CPU; my machine is a lowly 4GB RAM laptop with a 2GHz CPU, and I am running it in a virtual machine called Sun xVM (formerly VirtualBox). Incidentally, I give win 7 ONLY 1.7 or so GB of RAM, and I personally feel the graphics in VCP in VirtualBox look better than in native Win7. My model pans, zooms, and redraws reasonably fast. Note, however, that when using the scroll wheel, the model moves jiggly if your cursor is over nested lines/curves. I think this is because the cursor (LogiCursor) is hunting for lines to populate the ‘ambiguity popup’ list. I just move the cursor around, tactically, to get the view I want then zoom in where I know the is not ratsnest of lines or curves to slow me down.

      Select as the current layer that which is in the hull area you will do the work. It’ll save time and headaches to always do the work on the desired layer, or some generic “staging ground” that is not going to tangle or conflict with layers unrelated to your intermediate work.

      When creating sideshell stiffeners, I select a station of interest. I create a line for the web, either horizontally or at some 20 degree angle, but of appropriate length for that region of the hull or compartment. Some might be 200mm, some 300mm.

      I then use one of the rail sweep tools with one of the several sweep methods a given rail sweep tool may offer. I also then create a line for the flange, maybe 80mm or 100mm or 200mm, depending on examples i find on the Intertubes, since I don’t have high-end specialty software. This sweep act creates the surface based on a web construction line. If your angle of choice is decent, the swept surface emanating inboard will be approximately equidistant and reasonably good for modeling, but maybe not for construction of very large ships as they will use their own cutting and nesting tools. For a yacht or something under 100′, you are talking about fractions of a millimeter, nothing to sink the boat.

      (When convenient or expedient, I take of copy of the “T” web & flange, and just translate-copy it to each station where I’ve decided there will be sideshell stiffeners.)

      The rail sweep work of each of these lines relative to the station in question is a one-at-a-time affair. (Unfortunately, no scripting, no array sweeping.) So, in my case, having 15 compartments, with some 5-8 s/shell stfnrs, i have a lot of work. But, I don’t want to always mirror, so my work may be additional. Fortunately, VCP has a Mirror copy, so if I change the line lengths of the web on starboard, my port mirror changes.

      (Rant On: Oh, I detest bow-to-the-right, so in DS/FS/HS i painstakingly mirror copy everything and z-axis rotate the hull, and then destroy the port side. Rulers (other than arch/engineering rulers) read from left to right. Most of us read from left to right. Most of us pull tape measures from left to right, and other than in drafting class, my brain goes NUTS stacking up numbers from the right side of something going to the left. I understand that propellers were drawn first, and on the left of the roll of paper in the olden days, but sometimes “tradition” is a major PITA — particularly when computers don’t care but humans DO… (rant off)

      Similarly, do the same for the stringers, using waterlines. Nicely, since I don’t break waterlines, I can start a T stiffener at the stern on the CL, then tell VCP to sweep it along that curve. Once the curve ends, the sweep ends. I can use a cutting plane to lop off excess material once i’ve drawn all the stations and stringers i need.

      I also thicken the surfaces. While still in the sweep mode for a given surface, i use the “Ctrl” key when I need to “flip” or throw the thickness to the opposide side of the swept surface.

      Periodically, I use the materials properties facility to assign (in my case) SAE steel type to get the massprops, CGs, and moments. VERY, VERY BEAUTIFULLY, VCP gives two types of mass props info, depending on whether you select just ONE solid or whether you select multiple solids. Actually, it displays MOMENTS according to whether you’ve selected a single solid or multiple solids.

      Now, note that all of my model is in ONE HUGE drawing. WHY? I want to be sure that my CGs and moments info stay consistent. Yes, I could break down the hull across files to reduce file sizes, save times, and opening times, but layer mangement could become a royal PITA if I ad-hoc wanted to rename a layer. I’d rather go through the pain in one file rather than 15 or more.

      Plus, if you want to place + marks at each CG, VCP will do that. You could put them all on a single layer, then show ONLY those CG + marks and visualize your model that way, if that tickles you. Some people I know do each compartment in an ACAD file, and don’t care that the dwg has x=0 for each compartment. I cannot STAND that. If I take a measurement or imagine that I will receive a laser scan, i want the scan refs to very closely track the model’s notion of the BHD ref along X. It just makes future calcs less tedious and appear more thought out.

      Also, if I want to see the whole model, it is there. I’ll later on save a copy, then progressively delete whole layers and resave, progressively resizing the drawing file downward. That wholeness of the model also means my mass properties information is in one place. The mass information can be exported, and it is far more spreadsheet and .dbf ready (either text file that you can easily turn to relational database model) than that I suffered under in ACAD 2008. I havent’ bothered to see if ADesk bothered to revamp their massprops tool and its output, but it was maddenign for me since I don’t do scripts/macros, and I don’t suffer crappy text layout that demands the use of a programmer when mass information should be IMMEDIATELY useful on export, that is columnar and row data need to not be intermixed with formless information that has to be manually stripped or reformatted…

      (An aside: For a CAD app not aimed at naval architects, VCP does rather well for me (I’m not a naval architecty by ANY stretch of the imagination, but i CAN create GAs that worry some people. In Tokyo in 2004, some Mitsubishi people who saw my drawings didn’t know what to make of me when I tried to show my PAPER drawings, and our meeting was very short. All the while, one (a senior person) kept saying “NASHHUNAL SEEKRETS”. And, they refused to look at my drawings, eyes averting. Maybe they thought I was attempting to set them up for idea theft or something. Others who were engineers in my hostel kept asking me what Naval Architecture program I graduated from. That despite scrawls and bad linework, hehehe… end of aside)

      Anyway, ViaCAD Pro will set you back some USD $250 prior to any coupons or 3rd party reseller offers. VC 2D/3D is about $99, but lacks some 3D tools that are in VCP. Sure, Rhino/Orcad is a well known (but costly to me) path but not all of us are designing for build, but PRETENDING to design for build. Anyone who got a hair to build my ships would import them and re-rationalize the bits they like by using their own shop tools or yard tools to avoid going crazy with my naming conventions and layers names.

      If anything, VCP makes for good pre-vis in color. I get mesmerized looking at shell and deck plating work when it reaches as stage of panning and zooming and mass information.

    • #35134
      C . Schramm
      Participant

      Hello,

      in the Version of Delftship before the actual release (4.46.158) it has been possible to generate a new face via extrusion from a edge that is not a boundary edge. Unfortunately this capability is not available in the new version mentioned above. The calculation of the hydrostatic data has been interfered, if I did so, but therefore I have got the possibility to obtain the masses of any surface in the design model.
      Is thre any possibility to withdraw the rule, which prevents from generating surfaces at any position? This would be an easier way to plan internal structures of a design.

      Regards
      Christof

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