Using AttachGHSData based on curves is not giving correct results:

Lots of points are being skipped. The basic section curves only have about 12 points each.

Hello - if you think there is a bug here, please attach or send a file to with a link back here - an image is not much to go on.


What is the unit system for your model? That can have an effect on what points are selected to define a station

Nice call, that was it. The model was in mm. Changing it to feet solved the issue. I’ll pass this on to all the team working on GHS models. Thanks!

Why is this the case?

I have just had a similar issue, some sections generated by AttachGHSData on a polysurface were incomplete. Units were mm. Changing to feet resolved the problem.

Now I’m wondering how many GHS files I’ve built in mm are incorrect, affecting downstream stability assessments?

The only reference to feet or units in the AttachGHSData help file are not relevant to model units requiring being set to feet.

This appears to be a different issue than the previous post where the entire hull’s physical size ended up being more of a boat for the bathtub than open water (it was modelled in mm with sizes that were obviously not meant to be mm).

I still need to investigate further to figure out why the sectioning code is not making the correct sections near the bow.

Thanks Steve. Let me know if I’ve boned up something.

Any insights into this yet?

This is now project critical so I have sent files to

@Ncik did you get a response? I do not see anything outstanding from you on


I still have this on my todo list. The item is assigned to me Pascal

Ah, Ok - thanks.


Thank you @stevebaer and @pascal,

I have resolved this particular problem by rebuilding the bottom surface. However the first attempt at rebuilding the bottom surface resulted in the same problem but with different sections produced.

Basic procedure that produced similarly poor GHS sections was:

  1. DupEdge along the free bottom edge.
  2. RebuildCrvNonUniform
  3. Loft
  4. Join

Replacing the Loft with a DevLoft resolved the problem. No idea why.