Why is spline patch of hull surface denting in at sheer line near corner point of rising bulwark?

DELFTship forum Hull modeling Why is spline patch of hull surface denting in at sheer line near corner point of rising bulwark?

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    • #37330
      Ralph Grothe


      I have drawn the lines plan of a sleek 2nd Generation container ship, i.e. TS ADRIAN MAERSK, built 1975 by Blohm & Voss AG, Hamburg, Germany.

      You can find a few photos of her sister ship the ANDERS MAERSK (later MAERSK BRISBANE) at Shipspotting.com.


      © Yusuf Bilici


      © Marc Piché


      © Tomas Pinas

      And I found a photo of a model of ADRIAN MAERSK on this Japanese blog site.

      Though the hull lines are reasonably fair altogether (I only use the free version of DS that lacks the autofairing feature)
      there is still one spot that sort of drops out, a kind of singularity, which I don’t get faired.
      It is in the vicinity of a corner point at the sheer line where the side of hull is lifted to form the stern bulwark.
      I marked the spot with a red arrow on the screenshots below.

      I found out that sometimes additional grid edges that are drafted diagonally towards the hull’s top boundary edge (usually a bulwark edge) through the neighbouring grid faces sometimes remedy these unwanted bends and indentations.
      But here that didn’t help.

      Is there a trick that could be applied to overcome this annoying loss of curve control?

    • #37363
      giorgio zuppin

      Hi, D.Wood.
      I was surfing the forum and noticed this no reply topic: enough to become logorroic…
      It’s a normal issue rising bulwarks, if you keep a squared spaced grid the crease edges proxy to the abrupt change of direction, stirs the mesh.
      Solution: as a routine double the grid to the crease edges, as close as you can.
      Make test adding normal edges within the spot to ” normalize ” the tension of the mesh – help you with the ‘interior edges’ wiew.
      When you find a suitable arrangement of points and edges, memorize and use it as a tool of trade and remember – less is better.
      Regards, Jurgen.

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