Over here I am working on a vessel hull script to add a ‘round bilge’ to a developable hull shape that I model and edit in Rhino. So a Rhino surface is input for GH.
In order to have a visual feedback when I edit the amount of bilge, it would be nice to have the isocurves at two knots positions.
In the attached Rhino file and GH script, you will notice the isocurves in Cyan color as a Rhino object to give you a reference for what I need.
Is there someone who can give me a direction how to make this happen? Developable with round bilge - Discourse.3dm (2.0 MB) Developable from surfaces - Discourse.gh (16.6 KB)
Dear Leopoldomonzani,
Thank you very much for your practical solution. I feel very grateful for that.
And although I’ve a lot of GH experience, I never bumped into the ‘Iso Curve’ component.
Approximate the location of the knots in the surface with the two sliders, is a practical first solution. However, it would be nice to find them automatically.
Do you have an idea how to get these locations?
In Rhino I can object snap to these locations with the ‘knot’ toggle. But how to do so in GH is a big question to me.
A ‘round bilge’ (radius chine) is already in the Rhino file (layer ‘Bake from GH:01’)
Its source in Rhino (layer ‘surface to GH’)very mysteriously is a single surface without an edge where you want the radius chine (instead of a brep polysurface, as expected)
I’ve created many CAD sailboat hulls over the years, including radius chine hulls. For the last 10+ years, all were created entirely in GH.
Hi Joseph,
Thank your for taking your time to jump in on this topic.
As you might have noticed, this specific hull shape has to be developable at the side and the bottom strake. In between these two strakes there’s often a round bilge. So one of my strategies with these constraints is to have a hybrid Rhino/GH solution. In Rhino, I model the side and bottom without the bilge. This surface I can edit and maintain developability with surface continuity Gaussian analysis command.
Then I use this surface as input in GH to add a variable round bilge to it.
And yes, with only GH it is perfectly possible to model many types of hull shapes.
Your image of the multihull looks very nice. It looks like a proa hull.
Again, this single surface below (layer ‘surface to GH’), without an edge at the chine, is a puzzle? It’s just wrong and makes the task more difficult.
This version ‘c’ may be the most geometrically accurate yet, though it’s difficult to explain and could be better. There is an obvious flaw, holes at both ends of the radius chine.
The yellow group tries and fails to fix the holes by connecting the output of Replace Items to the ‘t’ input of the adjacent PFrame, but smaller, irregular holes remain.
Hi Joseph,
It is very nice that you’re working on designing proas. I love them!
In Rhino it is possible to model the developable hull with two developable surfaces first and then use the _FilletEdge or _BlendEdge command to create a continuous or variable round bilge. Now in Rhino 8 it is even possible to edit the round bilge afterwards, so that’s the other option.
However, I really like the extra features in my GH script like having displacement and CB calculation and a lines plan for example.
So my scripts are often generated more from a ‘practical use’ point of view rather than trying to put the whole design procedure in one script without Rhino modeling/editing.
Yes, I love your totally different approach here.
When I saw decades ago in the Rhino forum how a pipe in Rhino can split two surfaces for a radius or blend as a second step, I etched it in my memory.
Also I learn from your script some nice ways to solve things and the usage of components that I never use.
Thank you again!
Later I will take a closer look at these solutions from you.
And yes, the holes at CL is what I also experienced often when modeling in Rhino.
Thanks again!
Can you please post that version, before _FilletEdge or _BlendEdge I have an idea for avoiding the holes and would rather avoid isocurve to derive that edge.
The term “round bilge” bothers me every time I see it. The term “radius chine” is common.
I looked again at your original GH and realize I got fixated on making the radius chine fully parametric (without noticing your list of “‘Radius’ from stern to bow” text panel) and ignoring other parts that I still don’t understand.
However, I strongly object to the suggestion that putting “the whole design procedure in one script without Rhino modeling/editing” is not ‘practical use’
In this file you’ll find two surfaces, one before the _BlendEdge and one after the _BlendEdge.
The _BlendEdge command does a good job at center line.
And yes, the term ‘bilge radius’ is most common in the maritime industry as people only had a compass in the old days to describe the shape.
Hydrodynamic analysis however has shown that a ‘non arc shape’ with better continuity to the adjacent surfaces is more efficient. That’s the reason that I like to introduce another term ‘bilge roundness’.
I spent a lot of time adapting my code to use the hidden layer ‘01 Master Hull’ (internalized) and use your list of radii with VPipe(Pipe Variable). The holes are still there (might close them later); I added a yellow group at the end to get two edges on each hole.
I have an idea for avoiding the holes and would rather avoid isocurve to derive that edge.
