Hull Forms

I am asking this for educational purposes. I have a set of hull surfaces that works. However, Rhino folks frequently cringe at their density, A real ship hull has to be broken down into multiple surfaces due to features like corners. So is an example of a hull surface:

The surface was built with the dreaded NetworkSRf using physical frame locations and the outline of the sheer strake and bottom half siding. The alternative of using SWEEP2 produces an ugly surface with ripples.

And in a file:

Problem Surface.3dm (4.8 MB)

  1. I am working of an existing set of plans to a precision of 1/32".
  2. I have no flexibility. I get what I get. I have no need to edit control points.
  3. The hull points have to match points of other components. If I over-simplify a hull curve then something in the interior does not fit.

I note that FITSRF to 1/32" does does nothing.

I have seen several how to do hulls on YOUTUBE but they have all dealt with very simple hull forms or did not have nearly as many constraints (matching decks, frames, stringers, longitudinals, etc.).

Given those input parameters, is there some different approach that I should be using or should I just say, if it works leave it alone.

Hello - is that the regular way to make a hull, get the actual structure first as a constraint, and then match that with the surface?


That was the steel construction method until the mid part of the 20th century. A scale model was made. From that drafters found the XYZ coordinates scaled up to the closest 1/32". They must have had measuring devices extreme precision to do so. That did that for all the major internal structures and for the plating edges.

From those, full sized plans were created and plates were cut to them.

Hello - not having any more to go on than the existing surface, I’d say, if you need to split out panels, and you want them cleaner I’d split them out of this surface and then reconstruct each to a simpler structure if you need that, keeping to within some tolerance of the one you have.

Chopped out arbitrarily - surface is within .05 or so of the original.


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What’s the ultimate purpose?

Illustrations for rivet counters.

?!?! Who still rivets ships like that?

Not any longer but riveting persisted long past its obsolescence.

Can’t you just draw the surfaces as simple as possible and then project a point pattern (grid) to the surfaces (similar to the CPs of the current complex structure), and then use these projected points for whatever use/connection they have with the interior?

// Rolf

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It’s a very dense surface so I can see why others might complain about it. But it really depends on the specifics of the downstream use. Some ship detailing software I’m familiar with would not handle that density on import.

I loaded your surface (magenta) and extracted the perimeter edges and then a few isocurves and did a network surf that you see here in cyan with iso displayed. Then I ran the ‘Point Deviation’ command and came up with this result. Looks like a .02 foot standard deviation over a surface that is 212’ x 75’ is good enough to merely count rivets!

Problem Surface (1).3dm (2.1 MB)

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