Re: plates tutorial

DELFTship forum Feature requests plates tutorial Re: plates tutorial


Hi Chiossul,

Are you trying to create shell stringers/sideshell stiffeners? That is, are you trying to create T or L stiffeners, such as web/flange plate?

I don’t think you can do that in Delftship.

What I did was to create my hull and fair it. Then, I added waterlines and stations, at various intervals where I thought I later on *might* need or want to add stiffeners.

After much fairing, i exported the DXF 3D Polylines and the DXF mesh. I then opened my CAD application and imported those files.

I assigned various waterlines and stations to conveniently named layers.

I color-coded things to make it easier to work.

Do you have a CAD application that can work with solids or create solids? I’m not talking about meshes. If you do not, then consider something you can afford. You have many choice, ranging from Rhino to Autocad, and Rhino with various add-ons.

If you find them to be too expensive (as I have) and are not generating cashflow from your drawings (as is my case), then you may want to try Punch! ViaCAD Pro. It is less than $300, and it has some pretty good 3D modeling tools. It is what I use. I like the look of the solids when I properly construct them. And, I like the reasonably-laid out and exportable CGs and Moments information that is calculated for individual and multiple solids in the model.

To create stringers, I sweep the profile or the web and the flange separately along a waterline.

Quickly, to generate stiffeners…

— Pick a waterline that will be your stringer’s path
— Find the stern (in my case i have transom sterns)intersection
— Draw a line that will be the web
— Draw a line that will be the flange
— Use one of the rail sweep tools you find works with the ending profile you’re wanting

— Thicken the surface using the “Thicken” tool. Before leaving the Thicken mode, zoom in to make sure it is where you want it. Use the “Ctrl” key to “throw” or shift the thickness to above, below, or exactly on the waterline.

If you like it, keep it. If not, then look at the angle at which you created the web and the flange. Nicely, the sweep tool will follow the line/curve even though it bends 90 degrees in the case of a transom stern of waterlines.

If you need to break those waterlines because later you want stringers interrupted by the bulkheads you might install, just break the solid with the trim or another tool. But, for that solid, some associative information may be lost. If you have to re-thicken the stiffener, it should still be possible later, but you might in some cases want to re-sweep the surface and re-thicken the solid.

Swept surfaces are associative to the curve used, so if you activate control points and move them around, you can force the surface to be reshaped. But, don’t get crazy — dramatic displacement of points could lock up the drawing due to calculations, since in 3D you might think you’ve moved a point only an inch or some number of millimeters, but if you are incorrectly using snaps, you might actually be moving a point by meters or kilometers in the drawing.

If you are creating sideshell stiffeners/panel stiffeners/bulkhead stiffeners, you can use the same or similar techniques.

* But, keep in mind that you want an app that allows you to export the solids information as some sort of dxf or delimited (comma, tab, etc) format. And, you want this format to appear STRUCTURED, not in some time-wasting mixed format that forces you to copy, paste, splice, and eliminate stuff that won’t neatly align into columnar format. Why? Well, you might later on want to run reports in a spreadsheet or a database app and don’t want to become a scripting expert just to untangle an insane or obtuse layout that is set up for visual use rather than analytical use.

* Clarification: I wanted to clarify that I am not criticizing DELFTSHIP’s hydros outputs and CGs/Moments info. I’m speaing of a well-known, very expensive, CAD app that requires some amount of scripting to get some decent formatting out of the mass properties information.