Develop plates in Freeship

Discussion in 'Software' started by Newhill, Jan 11, 2014.

  1. mrjo
    Joined: Jan 2009
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    mrjo Junior Member

    Have downloaded manual for 2.6 and that will make things a lot easier, the extra tips should help too, thanks tdem.

    Jo
     
  2. lewisboats
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    lewisboats Obsessed Member

    Use the window tile or cascade will show the minimized one down on the bottom, just click on the double window button and it will come back up. Then do a windows tile again. The windows will usually switch places and it is a real pain to get them back the way you want them. Not a feature I like.
     
  3. mrjo
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    mrjo Junior Member

    Have made some progress but am not sure on the best way to model an asymmetrical hull such as a Proa. The mirror function is one way but then it stops the hydrostatic calculations, as it seems that I need to create a full side mirror save it and then turn symmetrical off so I have one side only and then reinstate the mirror.

    All this so I can make a pod to one side of the hull if you were wondering.
    Any other way???

    Also re fairing I cannot make the chines show green, a couple of spots here and there, is it possible to get green on full length of chines?

    Lastly is there a function that gives best fit, say again for a full chine if all control points selected on that line??

    So 3 main areas I can't nut out at present.
     
  4. tdem
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    tdem Senior Member

    Modeling a proa is a whole new can of worms you are opening! You may find some tips here:
    http://proafile.com/multihull-boats/discussion-forum/viewthread/462/

    What I would do is turn off symmetry, and create both sides of the model manually (one side will have negative coordinates). Then you can enable symmetry for one side, do hydrostatics, then enable it for the other side, do hydrostatics. And then halve the result.

    There is no best fit, but there are functions for fairing a hull. They are not very intuitive to use!

    Select your entire chine, from the menu go "curve -> new". Make sure control curves are shown as visible, and turn off your control net, you should see a purple line on the chine.

    From the menu select "visibility -> curvature". When you now select the purple control curve, a curve of areas should show up in pink. You can use F9/F10 to increase or reduce the curvature scale. Now you turn your control net back on and move the points until the curve of areas looks good in all dimensions.

    If you use the "calculations -> intersections" menu to insert stations / waterlines / buttocks/ diagonals, when you tick the box next to them, they will also show a curve of areas when you select "visibility -> curvature".
     
  5. tdem
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    tdem Senior Member

    Another better way I just remembered: You can model both sides as above, but only model half the proa lengthwise. This way you can leave both sides as hydrostatic/symmetrical layers. (just untick "show both sides of model" and it looks fine). The nice thing is your hydrostatics will be correct! (Displacement anyway). You can use the "transform -> mirror" menu to get the whole boat I think.

    Also, when you develop the panels you will get the correct number for a full boat!

    The real problems come when your boat does not have a true "centreline" (eg a proa with non-horizontal flat bottom or something)
     

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  6. mrjo
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    mrjo Junior Member

    Thanks tdem

    plenty of info there, I will get into it later and see how it goes.
    I do have a true centreline so look forward to having no real problems :)

    Cheers Jo
     
  7. mrjo
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    mrjo Junior Member

    going backwards

    tdem I had no luck last night, managed to get something that looked like a proa fairly quicky a few days ago, thought this isn't so hard and now I can't even manage to replicate your simple screen shot!

    When I try to create the asymmetrical half model as suggested I am stumped at the body plan. with your drawing you still have the displacement curve, if I try to drop the end section to 0 the curve disappears.

    I am not even able to create "manually" the simple body plan outlines you have. Feeling a bit stupid about that. I open a new model and put in main dimensions then body plan pops up and when I attempt to change it all goes haywire.

    If you could please enlighten me to the step/s I am missing.

    Jo
     

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  8. tdem
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    tdem Senior Member

    I'm not sure what you mean with dropping the end section to zero. You have to make sure you have no leak points, as usual. Leak points are shown in green (you have one on the keel line in your screenshot).

    This also means you have to create a "transom" at midship/stern.
     
  9. lewisboats
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    lewisboats Obsessed Member

    Best way I have found is to model half the hull, deselect the symmetrical, mirror it and assign the whole thing to one layer. Then export it and import it as a part. Then you can use it and modify it as you wish... moving it off center etc.
     
  10. philSweet
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    philSweet Senior Member

    As for getting the developable green/red thing - Using freeship as cad with lots of components tied to the hull really messes up the grid and freeship's ability to judge developability. For developability and hydro calcs and hull offset exports, I find it best, if not very convenient, to keep a separate hull file containing only the hull shell and nothing else. That way you can make the grid completely regular without interfering with other layers. Freeship has trouble with three sided faces wrt developability check. Also, set the grid increment to high or highest and set control curves on all chines/layers at the earliest opportunity.
     
  11. mrjo
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    mrjo Junior Member

    Thanks for all the tips, tdem one step I did miss was the transom! a fairly large leak point. the proa above was the first model I have done and well it doesn't have one.

    When I said drop it to zero I meant when I started to lower the transom area to the baseline the displacement curve disappeared. I am still wasting hour after hour trying to figure out the few simple steps to create the asymetrical screenshot by tdem. It looks like could be the way to go but I am just not getting it.

    Something is stopping me from seeing or correctly reading the steps to follow.

    If I do it as Lewisboats suggests does importing as a part mean hydrostatics will work? I assume not.

    Jo
     
  12. lewisboats
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    lewisboats Obsessed Member

    Why? If you mirror it correctly about the centerline and there are no holes (say... a transom missing...) and the hydrostatics are correct then when you export it and import it as an ama and offset it it should be water tight. The hydrostatics should still work. It did for me.
     

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  13. tdem
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    tdem Senior Member

    That is a clever way to do a catamaran!

    Interestingly, I just tried to recreate my screenshot (I made the model a long time ago), and my buoyancy distribution curve is not showing (displacement still appears correct though). I'll have another look when I have more time and post some instructions. Basically use face-> new and splitting edges and inserting edges to create the other side.
     
  14. mrjo
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    mrjo Junior Member

    I am still wondering tdem if you found a solution? (I took a break for a while).

    One question to all, Has anyone actually made a proa design that has been built using Freeship?
    Considering the option of buying software that is not asymmetrically challenged, any ideas of the best to use
     

  15. tdem
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    tdem Senior Member

    I remember a web page a few years ago where someone designed an asymmetric proa using FreeShip. They started building, but I don't think it ever got finished.

    They used a technique of having a separate model for the windward and leeward sides. This works well if your windward and leeward sides are for example 1:2 asymmetry, but identical in all other aspects, you just use the layer -> scale dialog to create the second model. A bit more hassle for hydrostatics obviously.

    On http://www.multihull.de you can find Delftship files for the p5 proa, although I don't think they were actually used to design and build the boat.

    I did have another look at the problem. I found the solution but can't remember it for sure now! I think.... that you need to have the top edge of the "negative" panel on the "positive" side. (A deck will accomplish this). It appears to be some kind of glitch in the software that allows it to calculate "negative" displacements, that work. At least, I think they work. I'll have another look at it soon.
     
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