FreeShip Question

I haven't tried it, but another method that might work is to choose fine resolution, export that particular station, reimport as a marker to check size - and then reload just the bulkhead as a separate model to say get a dxf if that was desired. In any case you'd have a whole quick set of offsets for that particular station/bulkhead with minimal manualization.

There are bound to be differences between the model and the markers, but it would be interesting to see where it deviated. If you reimported the station as markers into the new model, it would be quick to make the minimal modifications necessary.

Just to repeat, I haven't tried it - but might be worth checking.

 

Maybe my version (2.6) is old or the free version is missing a capability but I have found no menu items that permits addition of the bulkhead. Adding a plane creates new points on the existing control lines which changes the hull shape; the control line connecting the new points is not creased so creasing it makes things worse. The export menu does not include markers so I cannot export and reimport those to fixe the hull shape either, at least with the version I have.

 

Make a test model. highlight and extrude an edge about .1 then extrude it again to give you a square-ish shape. Turn on interior edges and highlight the first little extrusion you made and delete it. Highlight the big extrusion and export it as a part. Import the part into your model and move, rotate and shape it into the space you need...voila! a bulkhead. Make sure to uncheck the "use for hydrostatics" box if the bulkhead will go below the water as it may have leak points which will mess up hydrostatics. You can also turn it into a sail if you want. You should build up a library of parts such as keels, rudders, sails etc...that way all you have to do is import one and tweak it for whatever you are working on. You can even do entire rigs (mast, boom, yard, sail) as a single .part. This will work in 2.6.

In fact I'll attach my 87 square foot Lug rig and a panel for you to play with

 

What I (LP also in the first part?) was referring to was a work-around of this issue. It would give a facsimile of a bulkhead. It never attaches to the model.

Because of the above, I only attach a 1st intersecting plane in locations where I know there'll be a change. ( a 2nd doesn't matter as the change already exists.)

Just like further up the page, I was referring to playing with the program's offset exporting file. So clear all your intersections and put one (for explanation purposes only) station ‘intersection’ at the location along the hull that you want it. Then export the offset either: 1) slightly modifying the file and reading it back in as markers and/or, 2a)slightly modifying that same file (to be a chine file I think) and reading it back in as a new model [say called 'bulkhead 2a'] and, 2b) adding the marker file to the model file as a double check to see how accurate the model file of the bulkhead (only) is.

I just tried it and the model import doesn’t work very well (for a chined shape at least [ I made 2 file attempts – knuckles only and high res], maybe only better for the unchined but I’d suggest care be taken on recurves). Firstly, a bit of file manipulation (3 chines) is needed to ‘make’ the station surface. (In the examples, I just used the first and last marker points, then one point over – you can see the 3 seams.)
The main issue is that the model file is only slightly related to the marker file. Too bad. It could be manipulated to be the right shape, but that could almost as easily be done in the initial model probably as a separate build.
If it was a complex shape, then maybe it would be worth doing this way. Then reimport as a part is desired.

Options anyway.

Here is a model for an unchined simple shape using high resolution. Note the variances from the markers at the bottom right - this might get much worse with a recurve.


And then note that a chined shape is much worse. As the markers are there, one could remanipulate it to get better, but it is not initially great:

 

Steve has it.

I will typically extrude an edge from hull centerline. Extrude twice and delete the first. This is your bulkhead to be. I never save mine as a part file, but then, I'm not very organized either. I will usually save my different pieces and parts into different layers so I can choose whether to look at them or not.

The resulting square is then manipulated into the desired shape with control points. More points are added as required to meet the needs od the model.

The attached photo is an example of a highly developed model using the method Steve and I have been describing. This was done with FS2.6.

 

As FreeShip is not quite designed for this task, I found it easier to use other programs after a hull shape is finished. Quite naturally this means more work if the shape is changed, but the bulkheads formed in FS do not follow the shape of the hull automatically either.

a) 2D CAD: Set stations and buttocks at designed frame, bulkhead, and stringer locations and export them. Work from there with regular CAD.

b) 2D CAD: Export the lines from FS and loft with 2D CAD. Quite easy and straightforward.

c) 3D CAD: Export the 3D polylines mesh and work with it. This turned out to be the best working way for my CAD software.

 

It is quite simple to set a station at the required location. On mature reflection that is sufficient for the current project.

Thanks everyone for all the ideas, which I am trying out to extend my understanding of F/S.

 

Don't forget that skin thickness is not calculated...in effect the offsets for the station are to the skin's surface... both of them... at the same time. When looking at your model you will have to decide if the surface you see is the inside or the outside and if the outside, what thickness the structure has, then subtract that from your station dimensions. This would mean drawing the station out full sized then redrawing it to account for the hull material thickness plus maybe a little for fudge factor.

 

In one of my many reads, maybe Pete Culler, the difference in hydrostatics was insignificant enough to him that he just set his lines drawings to the inside of the hull and could build bulkheads and frame directly from the lines. The hull thickness was an inherent addition that became as a result of the build.

Just a bit of trivial, off topic, something or other.

 

Say, a percent in breath, half in depth, 2 in length, and you will get 3,5% more displacement. Protects a bit against breaching the weight target in build.

 

I always design the hull to the outside anyway; I don't usually use FreeShip for things than developments in chined boats, plank areas and hydrostatics and that makes sure those things come out right. It's easy to adjust frames and bulkheads to skin thickness during construction, and provided I am consistent I am not likely to forget, although I did on my first boat . . .

 

FYI I finally found a use for the Insert Plane tool. For a canoe design I inserted a vertical plane with an offset equal to half the stem thickness to create the stem bearding line, which for this design is the rear edge of the stem. The front edge of the stem has constant width so shaping the bevel will be simple.

My file was drawn to the inside surface, if it had been drawn to the outside surface I could have used an offset of half the stem thickness plus the skin thickness.