Smoothly capping the bow of a lofted boat hull

I’m working on designing a small boat with a decked hull similar to a kayak or rowing shell. I generated a table of hull offsets, processed that into a collection of points, and then lofted the hull. But this still leaves the cap on the bow (and the stern, but I’m leaving that out for the sake of a MWE). I’ve tried a few different things including a network surface, but to no avail.

I do need to do this in Grasshopper, not Rhino.

I generated some rough profile curves that the bow should roughly follow, but they don’t have to be exact. Those are just there to give an idea of what I’m hoping for.

Any help would be greatly appreciated!!!

MWE .gh file with internalized geometry:
partial-hull.gh (170.7 KB)

@Joseph_Oster ?

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Capping something that’s not a planar opening will eventually require a case-specific workflow. Some plugins might offer something…just thought of ‘cap custom’ from Peacock plug-in, for instance, but I doubt it’ll give a deliberate shape.
Maybe you can swtich to SubDs so you can spatially manipulate the hull shape as a closed low quad poly then grab the smoothed result.
Alternatively, you can simulate (within grasshopper) what you’d do manually in Rhino via Edge Surfaces?

missing

I draw my hulls differently to avoid this problem. Looks like @Chay has painted himself into a corner.


partial-hull_2023Oct2a.gh (175.0 KB)

Too many points. And not the same number of points on each section curve…

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Thank you for the replies.

@René_Corella Right, the Cap custom module looks like it won’t take the hull brep into account. I’ll consider your other two suggestions and see how that goes.

@Joseph_Oster whoops, didn’t realize Close Curve wasn’t native to Grasshopper.

Each section curve has a different number of points because those are plucked straight from the table of offsets. And yes, I don’t need so many points. But your comment gives me an idea, to distribute an equal number of points across the entire section curves, interpolate through corresponding points and extend past the bow, then lofting the extension. I’ll give that a shot and report back.

That’s where I was headed but was stopped by the differences in points per section curve.

This video (by me) explains the technique and benefit of using very few guide curves:

P.S. The techniques described in that video have been refined but the idea is the same:




LOA: 21 meters

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By the way, another video I posted a few weeks ago (“Deadrise and Hull Shape in Rhino Grasshopper”) shows how fair NURBS curves can be created using only a few points instead of many from offsets.

This thread about may or may not be relevant: Boat hulls with smoothly curve stems - how to model