Why I don’t use Rhino

I know that Rhino is widely used in the marine design field, and I am sure with good reason, it was probably just unfortunate for me that the vessel that I modeled up and created cutfiles and structural drawings for was for an aluminium sheet metal cat.

Rhino as we know is a freeform surface design Cad package, with brilliant surfacing tools. It claims to have some ‘solid’ modeling functionality, but in comparison to the actual solid modelers available falls (understandably) short. My impression of the solid modelers is that they have included more and more surfacing tools over the last few years, and the surface modelers have become more niche.

In one of my previous companies I modeled up and produced drawings and cutfiles for a 14m power cat using Autodesk Inventor. An unusual choice for boat design in some ways, although as we know Solidworks is widely used in boat design and both programs share a niche. They are both mid-level, parametric, feature-based solid modelers.

So coming off this experience I went into trying to achieve the same results in Rhino…

Modeling the hull:

I have no doubt that Rhino can do a brilliant job at modeling up the compound curves found on composite hulls, but in this case I was only needing to create bilenear surfaces, so that the boatyard didn’t phone me up and swear at me when the time came to fit the plates! And yes, Rhino 5 does have the ability to create develop able surfaces that you can unroll. But in comparison to Autodesk Inventor’s sheet metal environment, Rhino unrolled surfaces that Inventor would have refused to. Perhaps there is some margin for error available in this function. But as my intention was to create unrolled surfaces for the real world there really is no point in being able to get away with something that will create geometry that the boatyard struggles to work with.

Then it was on to modeling up the frames. This went pretty well, although I missed my usual workflow, which would allow me to create a closed sketch on a plane, and then shift the position of the plane afterwards. I know that frame spacing is usually not something that gets changed, but in this case we needed to move frame 1 slightly more fwd. of the transom to have a big enough engine room, and maintain the standard frame spacing after that. So in practice I had to move all the frames!

Without going into the minutiae of every aspect of the modeling process, and just to summarize my overall experience. The vessel in question was very sensitive to gross tonnage, and the client had stipulated a number of requirements for the cabin layout. This meant that I had to rework the cabin geometry over and over, adding on 50mm here, taking off 50mm there, to fulfill the cabin requirements while staying within the GT. As my geometry was not driven by parameters this became an extremely time-consuming task.

Then it was on to production drawings and cutfiles: I was quite happy with the initial process of generating geometry from the 3d model and detailing the drawing sheets. But then the real world came in, as we all know, and the revisions started! I’ll spare you the blow by blow account, but for me the end result is that a drawing that I am accustomed to taking me 4 days in Inventor took me 2 weeks in Rhino..

The need to create drawing revisions is really what killed it for me. And while I can only blame myself for the errors that crept into the geometry of the drawings and cutfiles that I produced, these errors would never had happened had I been using Inventor.

I do think it is somewhat unfair of me to compare Inventor, which I had been using full time for 8 years to Rhino, which I had been using for just over a year. But the drawing revisions killed me, and I couldn’t see that getting more experience in Rhino would solve the issue.

So in conclusion, and of course this is purely my personal opinion: I experienced 2 issues with my Rhino experience. The first issue was the huge amount of time I spent revising both the 3d model and the 2d drawings. The second, less quantifiable issue was the effect that this had on me. I spent so much of my brain power on regenerating geometry that I was left numb. And the brain power I had left over to check my work was so diminished that a large amount of mistakes were not corrected on the revised drawings that I issued.

I am fully aware that many designers are quite happy to do this sort of work in Rhino, and they do it successfully. And I mean to take nothing away from the core functionality of Rhinos advanced surface modeling capabilities, it was just that my project had no need for that function, and I was working in a way that I believe Rhino was never intended to be used. I have since gone back to a parametric solid modeler, at the moment Fusion 360. But more on that in a different post!

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