Freeship and offsets

[pwbf]

I just downloaded freeship and I'm mainly looking to be able to put in existing plans for hydrostatic information and to modify drawn lines to finalize a lines drawing before adding build details. I've started out with a boat from one of John Gardner's books and set up the stations, waterlines and buttocks and then modified the control points to be the offset numbers I wanted. I understand that the control points are there to fair and manipulate the lines and should probably not be used as I have. However the hull looks pretty close to start and I'm wondering if there is a way to get the offsets I want from here or should I start over typing up a text file with the offsets in excel and bring that in. I've been scanning over the various freeship posts and haven't seen an exact discussion of this (unless of course I missed it). I'm just trying to see if I can do this with freeship and how to get a better understanding of a traditional offset table and the software. Attached is the file I started with.

[Gilbert]

You will get the most accurate representation of the hull in freeship if you put the offsets in an Excel file as you suggested. It sounds like you will want to use the 'import as chines' feature on the file menu. I haven't looked at your file so excuse me if I misunderstood.

[lazeyjack]

well gilbert, how do you see the offsets in freeship, please??

[SeaSpark]

Pretty hull!

Use File, export, offsets from the pulldown menu to create a text file with offsets.

[pwbf]

Gilbert thanks for your response but if I understand the manual correctly I think on a round bilge hull I would want to import as surface not chines. Lazeyjack I read some of the previous threads you were in with similiar issues and your right, this is still a question that remains in my mind as well. Is there a more direct way to work with offsets? If you import them from excel would the best way to proceed be to assume they are correct and then modify only knowing the numbers modification you have made when you export offsets, print and compare? I have read through the manual and understand all of the basic features so I have exported as offests. One thing that I didn't understand about the export is I have set up 7 control points at each station that pertain to heights and widths and when I export as offsets I get 29 points at each station. Again I'm just trying to reconcile the features and functions of freeship (which is great) with a traditional table of offsets which I understand very well.

[Gilbert]

Sorry about not realizing you were working on a round frame hull. Yes, you would want to import as surface.
I have only used the export-offsets feature once. It gives the information as what might be sent to a plotter to draw the curve as a series of short straight line segments. You even have to convert it back from decimal to feet and inches or just inches. In my case I was asking for offsets for making molds for a curved cabin for a small boat and I just marked off each point by hand from a baseline and centerline on the plywood I was using for the stations. A set of trammel points helps for this. That's a little tedious and archaic in these modern times -(have you all seen Charlie Chaplin's "Modern Times"????) -but it seems to have worked out well. So as far as I know, if you want a conventional table of offsets at this point you would need to export a dxf file or similar (maybe IGES?) to a drafting package and pull them off yourself. Someone please correct me if I'm wrong about this.
I hate being wrong, but I love being corrected promptly.

[marshmat]

Exporting offsets from Freeship:
FIle > Export > Offsets generates a text file of the table of offsets. To import this into Excel 2003: In Excel, go File > Open, set file type to Text, and select the Freeship text offsets file. It will ask about the data format. Choose the Delimited option. On the next screen, set the delimiter as Space and turn on Treat Consecutive Delimiters as One. On the next screen, defaults are good. You now have the offsets table in Excel in a decimal format that you can process however you want.
Importing offsets:
Making a table in Excel or Notepad is the easiest way to do this. If you have Michlet http://www.cyberiad.net/hullsoft.htm , take a look at the fsoff.txt file format that it automatically generates, as this is essentially a perfect FreeShip text surface file. Once you've seen the file it's easy to type up in any text editor. Remember that Freeship lists offsets starting at the stern. As with most computer programs, the format is decimal- so it's dead simple if you're in metric, but converting an old-imperial plan will require you to convert inches and eighths to decimal.

[pwbf]

Thanks Matt for the detail in the best way to work with offsets. Is there no way to see the offset numbers while in freeship without exporting offsets?

[marshmat]

For more details on importing offsets, see section 3.5.4 of the FreeShip manual. As far as I know, there is no method in Freeship for viewing offsets dynamically (nor do I feel there is a need for one).

[pwbf]

What I want to do with freeship is quite possibly the wrong application. That is what I'm trying to find out through the expertise contained in this forum. I have followed your advice (Matt) on creating the table of offsets in excel and imported them into freeship as a surface. What I got looks good. No stations, buttocks or waterlines. I put one station, one buttock and one waterline for the purpose of exporting a table of offsets. In looking at the information I understand that I'm just putting an arbitrary grid with what I've choosen on the object as laid out in freeship using the offsets I've entered. However what I don't understand about putting the information back into a traditional table of offsets is there is no cooresponding intersection at the station I entered in either the buttock table or the waterline table. So I have 38 station locations for the buttock width I entered but none that tell me what the height is at the one station I entered. If I can understand this about the software I would probaly agree with you that the information is not important. Just for the heck of it I'm attaching the files I created in attempting to understand this process.

[pwbf]

Ok, so part of the answer to my question for those of you whose understanding might be along the lines of my own is that the offsets generated by freeship are points related to interior edges. You will get more points within your offsets depending upon the level of detail you set the interior edge to. I think this is independent of the grid you impose upon the model so the offset numbers will allow you to plot the curves but do not relate to anything but the interior edges. This doesn't solve the problem of the traditional offsets but it does answer the question I started the post with.

[lewisboats]

For one thing, your boat is backwards as far as the program understands. This may be throwing things off a smidge. As I try to work with it it doesn't understand things properly. Redo your input offsets so that the boat is oriented correctly. It should look like the file below, with the bow to the right, and the working lines being the port side of the boat. If you open your file (cleaned up and sealed...sorta), then my file then flip between the two you will see in the body plan view part of the problem You should be seeing a similar view with the exception of the sides being swapped, you arent even getting that right now.

Steve

[pwbf]

Steve, Thanks for pointing that out. I had the offsets in the input file reading aft first down to forward. I changed the order, still didn't input correctly, then changed the reading of each station from sheer to keel, still no luck. Now I'm not sure how I need to redo the offsets to get the bow to the right and the port side being the control as opposed to the starboard. Not sure if it is the input file or something I have set in freeship (though that is hard to imagine as there isn't much to set). I have attached the text file below. Any idea how I need to change it?

[lewisboats]

Sorry, I have never used the offset input feature. Have you re-read the instructions in the manual? Perhaps you need to ask Martjin directly on the freeship forum.

Steve

[Gilbert]

Here is the file with the correct x coordinates for your boat to have it oriented correctly for freeship.