Freeship and Delftship

I know what you mean about revisiting old ideas. What's your current project? I ham having the devil's own job with fairing. My hulls start out fair, I am avoiding compound curves. Virtually chine designs with the edges softened. It's also a good way to pick up waterline beam without excessive displacement.
I will probably use durakore again for my next project, bullet proof, though I have ben thinking about a female mold CNC cut in MDF, faired off with car, Polyester bog! much easier to sand than epoxy. Too many hours long boarding is what I hope to achieve. For a one off or a short run of hulls should be OK. Any experience?

 

how?

How do I put both sides in one layer?

 

I use a different process with which I wound the glass on a jig, I want the hull and the deck to be one part. The other stuff gets fitted from the stern. I tested the process and it is very fast as well as give a good resin to glass ratio. The test layups I did came out impressive. But it's a whole setup I'm putting together and money is a problem, the economy is almost non-existent. If there is you get some done, if not then you wait.

I'm considering an 8m cat that would sport a bit of performance, also rigged so one can do a bit of fishing and fish at sea as well, not only fresh water. I also want a 9m cat that would allow limited live aboard, so I'm torn between the two...

 

Keeping a hull fair during changes can be a problem with FreeShip. I think a lot of folk start off with too many control points, try moving them one at a time, and get into difficulty.

When starting off a new design in FS I use one of the following methods:

1) create a mathematical design in a spreadsheet program and import the offsets in FS; I usually have to adjust stems.
2) create a hull in Carenne 2008 and save it as a XYZ file which FS will import; I usually have to fix the transom.
3) start the design in FS using the absolute minimum of points as described below.

I determine the minimum number of vertical and longitudinal points required to define a hull in FS by determining the number of places where I need to push on a batten to get it to adopt the same shape. For example a circular arc needs 4 points, a kayak shape with fine ends can be done with 3 points, etc. So for example if I want a more-or-less round section and circular arcs for the sheer shapes in plan I would use 4 points for vertical and horizontal control points. This also gives an idea where to place the control points.



The different methods above have different purposes. #1 gets me to the exact shape quickly, provided it can be expressed mathematically in a spreadsheet, but creates far too many points to make changes, apart from scaling. It is the one I tend to use at present as I am interested in the relationship between hull shape and construction method, and need precision. Method #2 is great for rowboats; Carenne 2008 does those well and has a very straightforward way of generating the planking layout for a lapstrake build as an expample.

#3 gets me to a simple canoe hull very fast - I have a few tricks. When modify a FS design, to keep it fair I try to avoid moving control points one at a time. Obviouslt one can scale the entire hull. One can select a line of points and scale or move them, one can probably rotate them although I haven't tried that - could be handy for changing the angle of a stem or transom, and so forth. There may be a bit of tidying up afterwards between the moved area and the rest but it gets the big job done fast and well.

Try to think outside the point-by-point box: for example a neat trick for designing a pram would be to create a conventional-looking hull but make it too narrow, then move the entire hull outwards to make space for the transoms.



Hope this helps with your efforts . . .

 

I tried attaching bulkheads to the hull, but I probably didn't do it right because I ended up with a lot of leak points. I no longer try to attach them to the hull. In Delft, what I do now is place multiple points (as many as needed on the edge of the bulkhead next to the hull and adjust them to fit to the curve. I go through this iteration of turning on a point then moving the point outboard in the Y plane, then turning on shade and rotating the model to see if the yellow peaks through the hull. I then move it back in the negative direction until it no longer peaks through the hull. This gives me a very close approximation of the curve of the hull.

I don't know if this can be done in Freeship. I do not think there is a shade command that fills in the color and makes the model look solid as in Delft.

 

Are you using control curves? That's what they are for, fairing lines. It took me a while to figure out how to use them but it does help. But in the long run you just have to keep rotating the hull. looking at the lines and adjusting, looking at the control net and adjusting and so on. It's a little easier in Delft because if you shade the model, unfair spots show up by being a slightly different shade of color and you can see the unfair spots.

 

Anyone have an idea about adding bulkheads and interior that will not ruin a nicely faired design? Or do you just export into another cad program?

 

The shade command is there in the right click menu in FreeShip also.
If you move your yellow point until it disappears then you will have gaps (possibly large ones) between the bulkhead and the hull surface. Remember, the point is not actually the surface unless it is part of a flat , non curved panel. The point actually pulls the surface and the curvier the surface the further the point is away from the actual surface. Zooming in in shaded mode on a curved area will confirm this. To get a good fit, assign stations to your bulkhead positions, export the offsets and it will give you the correct dimensions. Make your BH then assign it to a layer and trace the actual edge of the surface, paying attn to the Y and Z coordinates to make sure they closely approximate the #s in your offset table.

 

Thank You. I'm still learning. This will help with my projects. Frankly I am tempted to go back to pencil and paper and a good drafting table.

 

Frank, I haven't done it but the bulkhead cannot be extruded from the side of the hull as only boundary edges can be extruded. To do it right you'd want something that automatically finds the points where the bulkhead meets the hull surface. I think the Intersect Layers tool in the Point menu will do that but I've never used it. I would assume the bulkhead will have to be created in a different layer. It's past my bedtime so I'll leave you with that suggestion and logon tomorrow . . .

 

I tried out the insert plane function and it works well for inserting a bulkhead that is attached to the hull.

In Freeship:

First determine at what point, that is the distance forward of the Aft perpendicular (0,0,0) you want to insert a transverse Plane.

Go to Point/Insert Plane. Click on this and a dialogue box opens. Select Transverse Plane and, in Distance, put in the distance forward of the AP. I selected add control curve as well to be able to fair the curve, but you don't have to do this.

Select OK and a curve will appear on your model with points on it. Mine has five on 34 foot round bilge hull.

You cannot extrude from this because it is not a boundary edge, but you can create a new Face. Highlight the points by clicking on them. Use CTRL/left click

When they are all highlighted, go to Face and select New. A new face will appear. This will distort the hull. But, highlight the curve and select Curve/Crease and the distortion should go away.

The you can insert points in the top edge of the face by using Edge/Split, and then move those points around to shape the bulkhead.

You can also create a new layer and move the bulkhead to the new layer so it is not included in the hull layer, and this allows you to keep it from being include in the hydrostatics.

I tired this in Delft and it works as well. Use Plane Intersection. I inserted an new bulkhead all the way from the Cabin top to the keel.

This is far easier than extruding a plane and then moving it around to get it in the right place, and then having to shape it to the hull.

For boats with a deck and/or a cabin, create the deck and cabin first and then insert the plane if you want it to extend full height.

I have tried it and this can be used to insert cabin soles and lower decks as well. But they extend full length of the plane at the level you insert them. Whether they can be cut down to a smaller area, I don't know.

 

One of the problems is that the control points do not sit on the surface, but above it. the distance above the surface is determined by the curve of the surface and the distance between points. The boat must always be faired after adding bulkheads, so frankly I find using freeships for this, worthless, unless I am missing something.

 

Adding a bulkhead in FreeShip doesn't seem to do much apart from showing up in the perspective view for the pretty pictures, and perhaps getting the outline in the plank developments. It's simpler to insert a station at the bulkhead position and export the offsets; from a build point of view that provides the information you need. There are better applications for planning the interior. I must admit as a canoe design and builder it is no use to me at all.

 

ancient kayaker, right, and if a pretty picture is what you want, there are better way to get it. Freeships is a wonderful tool for what it can do well, and you cant beat the price.

 

Exactly; price per hull can't be beat! I am tending more and more to create hull designs in spreadhseets these days but I still import the results into FreeShip to validate appearance (the pretty picture) and hydrostatics in the first 2 images. I have to admit I do complete the decks - if any - in FreeShip but that's easier, just a few extrusions.

BTW I think I mentioned Carenne2008 earlier. It is much more intuitive than FreeShip, does an excellent job of planking design - ideal for lapstrake rowboats IMHO, and exports to FreeShip nicely. The ply-and-strip canoe shown in the FreeShip bodyplan view was started in Carenne. She's called Rose Lee after another half-way stripper.

Carenne insists on a transom, but for that I wanted a symmetrical hull so I cut Carenne's offsets file in half, flipped it and pasted it to the first half then imported into FreeShip. That confirmed the hydrostatics and plank developments were as I expected, and got me to the finishing touches in less than a half-hour. Tricks of the trade!