Autofair Function

DELFTship forum General Questions Autofair Function

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    • #44922
      Charlie
      Participant

      I am thinking about purchasing Delftship Pro for its autofairing function, but can find very little information on it. I’d appreciate hearing about anybody’s experience with it.

      I do however, have some specific questions:

      Will it keep locked waterlines locked, or does it shift them around?

      Does it shift the positions of stations, or can these be locked into place?

      I am modeling an early 17th century ship, and these ships were much “curvier” than later ships. Concave lines rapidly transition to convex lines, often with a nearly straight (but never completely straight) line between them. Also, some of the lines near the keel are, indeed, straight. Will the autofair function perform well with such a ship?

      How extensive is the documentation about the autofair function?

      OK, I could go on, but I’ll stop now. ANY information would be helpful. Thanks!

    • #44927
      Marven
      Keymaster

      Hi Charlie,

      Using the auto fair function will cause control points to be moved. This changes the shape of the surface. The location of waterlines and stations remains fixed, but the shape of the curve will change due to the change in surface geometry

    • #44929
      Terrance Egolf
      Participant

      Hello Charlie,

      If you are using the program mainly for documenting or reconstructing old sailing ship plans, I believe everything you want to accomplish can be done using the Free version.

      Please check out my reconstruction of a 19th century US brigantine at https://forum.delftship.net/Public/topic/modeling-the-1907-u-s-brigantine-galilee/

      If you have any questions, I would be happy to assist.

      Terry

    • #44930
      Charlie
      Participant

      Thank  you very much! Loved your model!

      At any rate, I believe that I can do what I want to do using the free version of Delftship, but doing so on this ship is rather painful. Each station consists of five different curves, some of which are very sharp, so describing them takes more points that I would like to use. Since I want a high degree of accuracy, I probably should be using Rhino for this, but that is waaaaay out of my price range.

    • #44931
      Terrance Egolf
      Participant

      Charlie,

      This program is probably still the best for modeling ship hulls of any digital software available. The need to add more patches and multiply polygons in regions of sharp and irregular curvatures is the nature of the way surfaces are modeled in DELFTship. Sailing merchant and naval ships prior to the last century had very curvy sterns and tumblehome. For example, this is the control net for my 1891 model’s stern:

      Galilee-Aft
      If I were to do this hull over again, I would have run the horizontal edges all the way from bow to stern, and the vertical edges from keel to rail. This avoids the breaks where edges stop in the middle of a surface. However, increasing the number of patches in a surface makes it harder to create a fair and smooth surface. Also, try to avoid triangles and polygons with more that four sides, if possible.

      You can use the built-in Grid view to adjust the control points to create a fair surface. However, I have actually found that building your own grid of station line, waterline, and buttock line intersections, in conjunction with the Gaussian surface display, works better for shaping the hull in most cases. There is even a Diagonal line option, which was often used back in the day.

      Depending on what plans you are referring to, for example, if they are copies of originals from a national maritime museum, you will likely find that they won’t produce a smooth hull in this program—that’s a problem with the old plans. You just have to do the best you can.

      If you aren’t a member already, you should consider joining (for free) Model Ship World. This is an international organization of maritime researchers and ship model builders (with 45,000+ registered members) who would be happy to provide information on ship plans and construction in the timeframe you are interested in. We also have a number of DELFTship modelers who can assist in your work as well. (My member handle is CDR_Ret.)

      Terry

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    • #44934
      Charlie
      Participant

      Terry,

      Thanks for replying.

      I guess I should tell you what I’m up to. I’m not working from old plans. Instead, they are my own hand-drawn plans of the Sovereign of the Seas (1637). I’ve been working nearly full-time on this project for about eight years, and had considerable assistance from the late Frank Fox who, as you probably know, was the preeminent naval historian regarding ships of this era. I was put in contact with him via another MSW member, who has been reading a rough draft of a manuscript I prepared describing these plans

      I know this is not the place for it, but I would really like to hear about the magnitude of the errors you’ve encountered in older plans. As you might guess, I know from firsthand experience how difficult it is to draw them.

      Am I correct in assuming that your ship is the Galilee?

    • #44935
      Terrance Egolf
      Participant

      Charlie,

      Yes, the Galilee has been my main nautical historical research project for almost 23 years (off and on). My maternal grandfather sailed in her for nearly two years (1906–1907) as a scientific observer while the vessel was under charter to the Carnegie Institution as a testbed for conducting geomagnetic data collection at sea. I have been corresponding with the recently-retired librarian of what is now the Carnegie Science Library since 2001. He was most helpful providing needed research materials.

      After frustrating myself trying to construct a set of workable plans using 2D software (CorelDraw), I finally discovered DELFTship Free back in 2014. I used the program to reconstruct the vessel from the only valid extant set of plans of the ship, which consisted of simply the three standard views of the hull, and the major deck and inboard bulwark structures. (No masting, no rigging or sails, and, of course, none of the unique magnetic observation structures and modifications.) The undated plans were developed by a member of the Pacific Marine Research Society named G.C. Berger. I have no information regarding the provenance of the plans. It seems that the plans were created sometime late in the ship’s history, well after she was converted from a brigantine packet ship to a three-masted fishing schooner—and then a retired houseboat—so I don’t know where he obtained the deck arrangement details as a brigantine.

      Thankfully, I was able to obtain many contemporary photos of the ship during the timeframe of interest, and was able to make numerous, if mostly minor, adjustments to the hull and other details. I am currently using Blender to construct the masts, spars, and rigging, since that program is more convenient for modeling those kinds of details.

      One significant issue I ran into is that the registered length of the ship couldn’t be correlated to the plans. On top of that, Berger used an unconventional method for designating stations. Consequently, I had to adjust the ship’s length nearly three feet to make it conform to the US merchant documentation practices in place in 1891 when the vessel was first built.

      The DELFTship program helped me realize that the three views of the hull were not consistent. For example, if one tries to digitally construct a hull from just the profile and deadflat views of the plans, the resulting waterlines don’t match those shown in the plan’s half-breadth view. If you try to construct a hull using just the deadflat station lines, the resulting hull isn’t fair. That is why I encourage you to use the program to construct the best compromise of the data you have available.

      From correspondence with other MSW members, this kind of problem appears to be quite common when researching historic vessels with limited documentation. Very old plans tend to be distorted and faded with age. Photocopied plans are often distorted by the scanning process. I found this to be the case with plans of Galilee obtained from the Smithsonian HAMMS project.

      If I might ask, what is your MSW handle? The MSW forum’s website is convenient and private for members to correspond.

      Take care

      Terry

    • #44936
      Charlie
      Participant

      That’s quite a story surrounding your ship! The family connection is great.

      At any rate, my MSW handle is anaxamander49. I hate the name and will change it when I can (MSW requires a certain number of posts before you can do that, and I haven’t reached that number yet). I agree that it’s better to communicate on these topics there, so I’ll keep this short.

      I do, however, have a Delftship-related question. Is there a way to ensure its accuracy, at least at certain points?  I want my half breadth to be EXACTLY 23 feet 1 inch, and that’s difficult to achieve by moving control lines around.

       

    • #44937
      Terrance Egolf
      Participant

      Charlie,

      When you get into a interesting discussion, you can quickly reach the minimum number of MSW posts needed to change your profile.

      Regarding your question: I have found that the best way to match hull surface shape to an existing plan is by the use of the program’s “Intersections” feature. The process should follow something like this:

      1. First, add your deadflat image to Reference Images, properly sized for your model, and so that the image baseline corresponds to the model’s. (I describe how to do this in one of my MSW posts. Contact me there to get my tutorial.)
      2. Next, in the Home ribbon, click on the Edit button in the Layers menu group. In the row corresponding to the model’s hull component under Description, check the box under the Intersections column. This makes any intersections you define visible in that component of the model. This step must be done first before any of the following, otherwise, you can’t designate any intersections in the model’s hull.
      3. Assuming you have already built a model and are tweaking its shape to the hull plans, go to the Intersections tool in the Project Tools menu group under the Tools tab. In the dialog box, select the Stations button to display all the active station intersections.
      4. If you have not done so, add the x-position of the station that represents the position of the Deadflat station. Normally, this will be the widest point of the ship’s hull. It is probably best if you delete all other stations in the vicinity of the Deadflat station to minimize interference with the view. (Note that this doesn’t change the hull’s shape, just the station intersections visible in the model.)
      5. Finally, back in the Home tab, click on the Control Net and Stations buttons in the Hull Display menu group to display both the Control Net and any Station intersections you have added.

      If you only want to manipulate the deadflat shape, the simplest approach would be clip the hull section where the deadflat is located using the Clip tool, located toward the right end of the toolbar under the ribbon. However, you will want to go over the hull first and bring it into something close to its final shape before you go any further. Realize that the Control Net influences not only the surface directly under a given control point but the connected surfaces adjacent to that control point.

      Once the hull surface is close to what you want, then activate the clipping tool at the deadflat, which should have control points either on the station line or very close to it. (See the image below.) Using an end viewport, carefully adjust the control points in the y-direction to move the associated station line (not the control point) so that it lies on the corresponding deadflat station in the diagram.

      Mesh-Arrangement

      Clipped section of the hull at the deadflat station.

      Realize that any major adjustments to the control points on the deadflat will change the shape of the hull surface adjacent to those control points, so this process should be done only when you are very close to finalizing the hull.

      In my brigantine’s case, the plans were not very good, so you can see that the deadflat station didn’t really follow the plan’s lines. I used the plans to get close to the desired hull shape, then used the shaping tools in DELFTship to smooth and fair the surface.

      Front-View

       

      Hope this information helps.

      Terry

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