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I've been playing with the free version of DelftShip (www.delftship.net) for creating hull designs.  I've done quite a few designs by hand but I've never been able to see how I could create a faired hull with 2D CAD: it would be too cumbersome.  

 

As an test, I created a model of a 30 m "frigate".  Although I didn't use all the tools for fairing the lines, it only took my about three hours to create this design.  I found the tools for pushing and pulling the hull into shape reasonable intuitive.

 

I've attached some of the output files:

  • Lines drawing
  • Table of waterline offsets (program can also output a point-cloud file)
  • Hydrostatic data
  • Resistance data - it looks like the hull speed is about 9 knots. 
  • Perspective renderings

The program can also use a table of offsets to create a model.

 

I didn't add decks, wales or ports, but the program is capable of this.  I did manage to add the keel, masts and a bowsprit, however. 

 

I'm not sure the ship modeller will find this too useful, but there is an interesting feature for laying out the panels of the develop-able surfaces for chine boats. 

 

Those who research hull design, especially how it affects speed, cargo and armament capacity, and perhaps seaworthiness, could find it useful.  I wonder how Chapelle's "Search for Speed Under Sail" would have benefited from being able to quickly do resistance analyses.

 

If anyone wants the Delftship project file, please contact me: this forum won't all me to attach it.  

FrigateResistance.pdf

FrigateHydroStatics2.pdf

FrigateHydroStatics.pdf

FrigatePerspective1.pdf

FrigatePerspective2.pdf

FrigateOffsets.txt

FrigateLines.pdf

Edited by lehmann
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  • 2 weeks later...

Good morning lehmann.

 

Nice work with that CAD model!

 

I've been using DELFTship Free for developing a set of plans for my brigantine Galilee project, which is featured elsewhere on this site.

 

I must be dense, but the program was anything but intuitive to start a project in. The manual is only marginally helpful. After a steep learning curve, I'm approaching the point where I believe I have a reasonable hull.

 

My reason for using the program arises from the need to correct the stern/transom shape of the vessel in the Smithsonian plans, which are the only existing complete set of drawings for the ship. I have a number of contemporary photos of the vessel that show a distinctively different shape. Chasing these kinds of adjustments around three 2D views is a frustrating task, while the consequences of making adjustments are immediately visible in a 3D CAD program.

 

I'd like to see more modeler interest using this program. It has a lot of potential for identifying errors in plans before committing time and wood to the build.

 

Terry

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I made some starts inthis program, and i gave up.

I can'tget the hull in a reasonable form

Some others dowo derfull things with it.

In the newest book of hoving at Seawatchbooks, there are some ilustrations done with delfship.

They look quite hightech

 

Jan

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What I want to do is to scan in a set of plans I have for the CSS Alabama. Use 'some' program to adjust the image to my scale; slice it up for 'room an space'; and print out the individual frame patterns. I am sure this is nothing new and probably what most people would want to do. Can you tell me if DelftShip can get me somewhat close to that?????
Thanks,
Larry
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Larry,

 

I can help get you started. I'm still tweaking the final hull form of Galilee, but it's the getting started that is tough with this program. I would recommend downloading the free version of the DELFTShip program and manual from here. Be sure your system meets the OpenGL requirements. Read through the interface and hull modeling sections, and then I can walk you through setting up a file, inserting the plan images, and then building up the hull. It's not intuitive by any means, but once everything is in place, the actually modeling is pretty straight forward, and produces a cool result.

 

PM me if you want to do this via email.

 

Terry

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Larry,
 
There are two ways to import a set of lines:  One, is to create a table of offsets.  The second is to trace the lines from a scan. To do this DelftShip has the option to put a scanned image in the background.  I think this was just to make a pretty picture, by, for instance, putting a picture of the lines behind the 3D model (see the picture below).  However, I converted the pdf of the lines drawing of my frigate into a jpg, which DelftShip can import.  What I ended up with is an overlay of the jpg image under the program's working set of lines.  In this case, I just imported the profile and buttock lines.  
 
Have a look at the attached file.  You'll see the working lines with the control grid that is used to control the hull shape.  The scanned lines are in the background and slightly offset from the working lines so you can see them.  I had to scale the scanned image a little, but the proportions were not distorted in the process.  To start the process, you'll need to create the basic profile and the spacings of the sections, buttocks and waterlines to match the lines in scanned image.  This will allow you to properly scale the image.

 

The one limitation is that only one view of the lines can be imported, as I did, unless you want to import the all views in one image that you then drag it around depending on the view you're working on.  

 

Overall, this looks like a viable method for re-creating a set of lines.  

 

Bruce

FrigateTracedProfile.pdf

post-17154-0-89123600-1433304719_thumb.jpg

Edited by lehmann
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Thanks guys for the offers to help. I have downloaded the program and the PDF of the manual. Give me a little time to play around with it. Before I retired, I used to install computerized accounting systems, so we will see how much of the tech stuff I can remember.

Thanks again,

Larry

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Not to disagree with Bruce, but you can import separate images into all three standard views (see the attached image of Galilee when I was working on her stern). Not that it's easy to do so, and if you don't hold your mouth right, you can end up with all three images in one view!

 

As Bruce said, you can import the model as a table of offsets. The manual describes how to do that, but it leaves out several gotchas and the terms they use for the different rows and columns in the text file are ambiguous. I would recommend starting your model this way if you have a CAD program that can display x and y coordinates for station and waterline intersections. If you try importing these into the program, it's going to look pretty messy until you create and designate the crease lines (edges where the curve of the surface is discontinuous). Considering you are doing an ironclad, I assume there will be a lot of those.

post-17233-0-96744000-1433349103_thumb.jpg

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Not to disagree with Bruce, but you can import separate images into all three standard views (see the attached image of Galilee when I was working on her stern). Not that it's easy to do so, and if you don't hold your mouth right, you can end up with all three images in one view!

 

I stand corrected (and educated).    Which way was your little toe pointing?  

 

I did try importing offsets that were created by the program - actually one of their sample models - and it didn't work too well, which why I recommended the tracing option.

 

Bruce

Edited by lehmann
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Actually it's not an ironclad. She's a three mast fully rigged ship, with steam power and a pull away prop system. She also had one of the first breach loading rifle guns on deck with a rail system for movement. That is what I like about her. She put an explosive round into Kersearge's stern area that failed to explode. If it had, history might have been different.

Larry
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Larry,

 

I stand corrected on the 'Bama. That would make a more interesting (and challenging) model to work on.

 

If you are going to model directly on a drawing, you still need a spreadsheet or table with offset-like (x, y, z) intersections to enter into the control net point editor. Otherwise, you will end up with a 2D model.

 

My suggested sequence to start this project DELFTShip would be the following, though this isn't the only way to proceed.

  1. Create separate profile, plan, and body view JPG files, all at the same scale. You will need a photo editor to do this. Make them as high resolution as you can (300+ dpi).
  2. Create a new project in DELFTShip. I don't have the program in front of me right now, but I think you just click on the white blank page icon in the upper left corner. Follow the instructions and save it.
  3. The 7.X version of the program has a Windows-like ribbon. Under the Home tab, click on the Project Settings button. Fill in the General stuff as desired. The really important thing to get right at the beginning is the type of units used. Select either metric or imperial (English), according to your plans. If you forget to do this and leave it in metric (default), when you go back and try to switch to English, it does a dimensional conversion, not numerical. In other words, if you create a model 150 feet long in the meters setting, and then realize you want it to be in feet, and switch the units here in the Settings dialog, the model is now 3.281 ft/m X 150 m, or 492 feet long! All is not lost though. Just use the Scaling feature on the Tools tab and scale length, width, and height by 1/3.281, or 0.3047.
  4. Still in the Settings dialog, click on the Main Particulars tab and fill in the Length or LBP (distance between aft face of stern post at LWL to intersection of stem rabbet at LWL), Beam (maximum moulded width), and LWL Draft to baseline. Galilee's baseline was the keel rabbet line. You will need to determine your plan's waterline baseline for this data. The Mid-ship location is set by default at 50% of Length, but if you have a station at that point, I would select a position between stations. This item determines at what point the program splits the stations between the front and stern halves of the body plan view. It should correspond to your body plan image you will be using. You also need to select the Longitudinal reference point. It defaults to the midpoint, but many plans use either the AP or the FP for reference. Galilee's plan used its vertical stern post for the reference. (I recommend the AP because all x values will be positive forward of this point.)
  5. The rest of the settings are of little interest to the modeler (IMHO).
  6. I can't recall exactly, but I think there is a default model in the new project window. Just select all and delete the model.
  7. The next step would be to add the three images in their appropriate views. This is done under the Tools tab. The process is addressed under Section 3.4 of the manual, but it's pretty vague as to the order of operations to make the process reliable and straightforward. I need to be looking at the program to explain this, so it will have to wait. For Bruce, I think it was more the fact that I held an eagle feather in my left hand, and shook the rattles twice before clicking Accept that made the images go where they were supposed to.  ^_^
  8. Some general hints on hull modeling from scratch:
    • Building a model using a Control Net is not the same thing as drawing an image in 2D. You are creating a subsurface framework that influences the shape of the underlying surface but is NOT part of the surface except at its edges and at "creases". Read Section 3.1 for a (very) brief overview of this modeling method. If you have used Blender or other subsurface modeling programs, then this should be old hat.
    • To create a surface, you need to first have at a minimum of 3 control points in different locations (see below).Then you have to select all the points that will be used to shape that surface. This is done by holding the Ctrl key down and selecting all the points one at a time (more control) or by band-boxing (less control). Then press the Add Face button (the manual's button doesn't agree with the program's here because the GUI was updated since the manual was published).
    • Connect the control points with control lines as desired. This is done by selecting two or more points as above, then clicking on the Insert Line button. For more control, I usually do this with pairs of points, though you can generally do a string of them as long as they don't form an obvious polygon. Otherwise, you may have lines connecting all the points to each other.
    • When you use the Add Point button on the Ribbon, it places the new point at the 0, 0, 0 location and displays the Point editor. To obtain a precise location, as with offset table coordinates, fill in the x, y, and z values in the point editor box. Note that x is positive forward of the longitudinal reference (a good reason to make it the AP), y is positive from centerline outboard, and z is positive from the baseline up. All coordinates are negative on the opposite sides of their respective reference lines.
    • One last thing about selections. In the newest version of the program, clicking on control points with just the mouse deselects the previous point selected (selected points are highlighted yellow). Not so control lines and surface patches. Sequentially selecting lines and patches keeps all selected until you press Escape. I think there is a Deselect All button in the ribbon with the newest version, but I haven't checked that out. This bug can get you if you are trying to select edges to make them creases, such as along the edges of the keel or stern post. You end up toggling one edge to uncrease as you try to crease another if you don't unselect it first. Very annoying.

I just noticed that the DELFTShip Free webpage doesn't have their latest manual available for download. You will need to send an email to Maarten Visser (maarten@delftship.net) at their site and request the latest (it should be "manual_714_282.pdf" or later and it's nearly 10 MB). If it's a later version, please let me know.

 

Got to get back to work, but if you desire, I can elaborate on some of the other basic processes and features sometime later.

 

Terry

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  • 1 month later...
Just to let you guys know that I have not forgotten about your offers to help. But things have changed. By chance I ran into an offer on eBay for Alabama by Revell at 1/96. I got her and she arrived today. Not quite sure what I will do with her construction, but that will work out....

Thanks again for your offers of help and, if I may, another great example of the type of people on this site.

Larry
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  • 5 months later...

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