How to get a “full” modell from a half one?

DELFTship forum Hull modeling How to get a “full” modell from a half one?

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    • #37103
      Niels Bruhn

      I have designed my first modell and of course it is only the port side.
      Now I want to rotate it longitudinal to see what happens to the drag but for that I have to use a “full” modell with both port and starboard sides.
      I`ve tried to show both sides first and also to mirror it, and than rotate, but the model rotates to left for the left side and to right for the right side. (it is “broken” midships)
      What can I do to get a “real” model which I can rotate completely?

      Ah – I use Delfship free with newest version just downloaded.

      best regards, Niels

    • #37104
      Kenneth Weir

      In your layers dialog window make sure the layer you used to model the hull has a check under hydrostatics. I believe that forces symmetric model.

      You could also try moving it away from the centerline & mirroring, then moving it back. That way none of it crosses the centerline, the program may like that a little better.

    • #37128
      Ralph Grothe

      Hi Niels,

      I’m not sure what you want to achieve.

      Your longitudinal rotation attempts sound to me as if you were trying to create one of those Geosim models that were used in serial tank testing and where they mirrored the hull against the deck to kind of create a vertical double hull, if my memory serves me correctly.

      But I think that’s not your objective.

      As rehlenah already pointed out, if in the layers property editor the boxes at Hydrostatics and Symmetric are checked (which I think is the default when you start a new hull) then your hull shall be mirrored along the ship’s centre line automatically by DS.

      Maybe you simply forgot to click the icon with the green (stb) and red (bb) semi hulls which is a toggle switch that either mirrors or splits your hull in all view panes along the centre line.
      But this is only the visual representation, which however has an effect on when you export the frames, which will either be exported as half frames or full (i.e. mirrored) frames.

      Apart from this the hydrostatics and power prediction calculations should be unaffected and work independently on the toggle button’s current setting, unless your hull has any leak point within the draft/trim/heel range that is covered by the hydrostats.

      Have you tried if the hydrostats and power predictions do yield any results apart from zeros when applied to your hull?


    • #37147
      Niels Bruhn

      Hi Ralph, thanks very much.
      I`ve carefully corrected the hull from leaks, and moved it a little bit away from basic line. If I went to the hydrostatics, it shows an incredible amount of drag (8kN @ 7knots) This can`t be true, because the forward power of the engine/Prop at full throttle is about 2kN or so in reality @ 7.x knots.
      So the hull must be less than 2kN.
      Suddenly, as I mirrored it again – the same hull (but now completely) has a drag of about 1.5kN. Wow! It works!-
      Than wanted to simulate the hull to get the drag at a heel of 15 and 30 degrees (for what I need the complete Model). But at this time, the program stops working giving me a error message of some mem violation. I couldn`d be started again, so I removed it, got a new installation file from DS and installed it newly.
      From this time on, DS refuses to open my files – (Program is older then the one which created the file – is the message) But that is impossible.
      Now it seems to be that an one week work is trash and I`m a little bit pissed (sorry..) Funny enough, all models I´ve touched with the first DS (downloaded a few months ago) will not work, even they are downloaded models, and all my ten+ backup files are also corrupted.
      Currently, I´m not sure if I will work out my boat as a model a second time… I`m afraid, it could happen again.
      best regards, Niels

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