FreeShip offset file (output)

Discussion in 'Software' started by Southbrook, Aug 28, 2008.

  1. Southbrook
    Joined: Aug 2008
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Long Island, NY

    Southbrook Junior Member

    Hi folks,
    (First, my apologies - I already posted this in the 'Designs' forum. It probably belongs here. Plus, after reading it, I clarified it a bit - I think...)

    I'm trying to get a conventional table of offsets out of FreeShip. I imported a proven surface file (reversedmoos.txt - thank you Gilbert), enabled intersection curves, took the defaults (13 stations, 2 waterlines, 4 buttocks, 2 diagonals), checked the display (looked good) and exported the offsets file. No problem so far. But...

    When I looked through the resulting offsets file, I found there are 38 (!) half-breadth offsets for each station (not counting the separate sections of the file for buttocks and diagonals).

    My (somewhat limited) experience with offset tables is that for each station, half-breadth offsets are only provided at the waterlines (and at the sheer line). So in this limited experiment, there should be two half-breadth offsets for each station (3 including the sheer). (Plus, of course, the separate tables for the buttocks and diagonals.)

    So now my question: - is there a way to have the FreeShip Offsets output file limit the half-breadth offsets at each station to just those at the waterlines? Boats in the size range I'm working with might have 10 stations and 6 or 8 waterlines (plus 5 buttocks and maybe 2 diagonals.) I need this traditional format for some museum work.

    Thanks for any help you can give me with this.
    Frank
     
  2. Guest625101138

    Guest625101138 Previous Member

    Just set up waterlines and stations initially and see if you can interpret what you get.

    Rick W
     
  3. Southbrook
    Joined: Aug 2008
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Long Island, NY

    Southbrook Junior Member

    Hi Rick,
    Thanks for the reply. I tried turning on intersection curves for waterlines and stations before loading the surface file, but that selection in the toolbar is disabled until a model is loaded. Once the model is loaded, the Offsets output file behaves as I described above, without regard for the intersection curves settings.

    Note - I also noticed in the Offsets output file that the number of half-breadth offsets at each station varies from station to station (between 28 and 38 half-breadth offsets), and has no correspondence to the number of data points in the original surface file (which has 7 points at each station, except 6 at the stem). Tiz a puzzlement!

    Thanks for the suggestion. If you have any other ideas, I'll be happy to try them. Something's gotta' work!

    Frank
     
  4. Guest625101138

    Guest625101138 Previous Member

    Frank
    One of the things to look at is just a cylinder as this is easy to understand. It is still wrong because when it is imported as a table of offsets it gives some rubbish. I have never bothered to figure it out. Have a look at the attached file and then have a go at importing it as a table of offsets. I think if you fiddled with it you could get the structure right.

    I have a couple of ways to get around it but it does frustrate me that I cannot get precisely what I expect.

    The easiest way I have found for stations is to turn on the stations in the intersection table, turn off the grid, maximise the bodyplan view showing the stations then take a screen image. I then place the image into an image handler such as powerpoint, scale correctly and print up as many stations as I want. I cut these out for templates of course with paper double so I get full stations rather than half stations.

    There is another way to produce a recognisable coordinate file for stations by exporting to Michlet and then using Michlet to produce its offset file that is actually station and waterline intersections. This is exactly what you ware asking about I think. I have attached one for the underwater portion. To get the whole hull you must submerge it before export.

    I guess one day I will spend the time to understand how to get the result I want but so far no joy. If you work it let me know.

    Rick W.
     

    Attached Files:

  5. Southbrook
    Joined: Aug 2008
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Long Island, NY

    Southbrook Junior Member

    Hi Rich,
    Thanks again for replying, and thanks for the new ideas.

    I'll try generating a simple cylinder and see how that goes.

    I tried the FSOFF1TXTt file, and still find unduly large numbers of half-breadth offsets in the output file.

    I couldn't get the New_Model.txt file to load as-is. I tried reformatting the file to resemble the normal FreeShip input surface text file, and got it to load, but didn't get anything recognizable in the viewports. Not sure what I did wrong there. I'll fiddle with that a bit more before I give up.

    I am reluctant to resort to scaling off small printouts. I am attempting to measure the original boats with a surveying Total Station, and am hoping for full-scale accuracy within a few millimeters. I afraid that accuracy would be lost when scaling small printouts. (Part of this effort is for display purposes, and (the more important) part is to gather precise measurements of these boats while they are still in measurable condition.)

    I will try your Michlet idea and let you know if I have more success with that.

    Thanks again for your help with this. And if you have any more ideas, please keep 'em coming! I can use all the help I can get.

    Frank
     
  6. Guest625101138

    Guest625101138 Previous Member

    Frank
    The fsoff1.txt file can be imported into Freeship as a surface. You then see the hull. It is in quite fine detail. FRom memory 31 stations and 21 waterlines. This is the default setting for export from Freeship to Michlet. I can be altered.

    Anyhow this is what you will get if you go the Freeship Michlet path but you can choose the number of stations and waterlines at export.

    The New_model is a 6m long by 400mm diameter cyclinder. I thought it should load but it gets the surface wrong. It is not being generated correctly as far as I can determine.

    The accuracy of what you produce going the screen image way will depend mostly on the scale you are working with so a big printer helps. I just do the templates to avoid having to measure things. I have not quite got to the lasaer or router cutting process.

    Rick
     
  7. Gilbert
    Joined: Aug 2004
    Posts: 525
    Likes: 5, Points: 28, Legacy Rep: 28
    Location: Cathlamet, WA

    Gilbert Senior Member

    I don't think I have seen the subject of exporting offsets from freeship discussed other than in this thread. I have been waiting before postiing to see if someone had "the answer". I hope there is a magic way to do it and someone will post here.
    What I would suggest doing in the meantime is to export the stations to drafting software in whatever file type would work and then setting up a grid to pick up the dimensions for your offset table. This is a bit tedious but it won't take so very long and it should be very accurate. Autocad pretends it is accurate to four decimal places.
    Another manual method I have used while staying in freeship is to zoom way in on an intersection that you want to know the coordinates of, place the cursor on the intersection, and then read off the numbers after the file name at the top of the screen. You can tell if you are zoomed in far enough if you wiggle the cursor around a bit and the number doesn't change. You are then at the limit of the accuracy. If your file name is too long, the numbers for the coordinates will be off the screen, so you will have to have a pretty short file name for this method to work.
    I know......I know...........we all want to just push a button and have the printer spit it out. And it is possible. Just how do we get there?
     

  8. Southbrook
    Joined: Aug 2008
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Long Island, NY

    Southbrook Junior Member

    Hi folks,
    First, thanks to all for the continued suggestions.

    Second, please don't think I'm ignoring your help (or that I've found a solution and I'm keeping it secret...) but I've had to put the 'table of offsets' aspect of the project on a back burner while I work out some other details in the job. When that's under control (ha!) I'll be able to get back to the table of offsets and I'll let you know how I make out with the various suggestions you've offered.

    Thanks again - keep the good ideas coming. I'm grateful for all the help I can get.

    Frank
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.