My introduction to PolyCad

One again my never-ending quest for top notch free software led me to PolyCad, a hull design, hydrostatics, (and now hydrodynamics) software package.

I am not a Naval Architect, and don’t pretend to be one. I am more than happy to leave the number crunching to the experts and to spend my time solving geometric problems as opposed to numeric ones. But I do have a working knowledge of the hull design process, and the role that design pressures and a weight study play, and how important these elements are. I have witnessed first hand what can happen when a vessel with an incomplete weight study gets launched..

PolyCad is a free software package that Marcus initially developed as part of his studies, and that he has continued to add functionality to in the subsequent years. In addition to its various hull modelling methodologies, it also supports importing hulls from a number of other programs. Once the hull is imported, a full report on the vessels hydrostatic curves, section area curves, floating position and GZ analysis can be generated. His latest update also brings in resistance calculations, although I haven’t touched them yet. Two of the functions that excite me are the ‘generate lines plan’ and ‘table of offsets’ functions. Without the correct software, producing these drawings is extremely time consuming.

As my forte is 3d modelling and design, I spent time following the wonderful video tutorials that Marcus has made, taking me through a few methods of modeling up different hulls using his X-topology modelling method. I feel that his principals could be applied just as easily to other software packages, as I have no doubt that he really knows what he is talking about. As this is the only hull design package that I have tried, I can’t make any comparisons. But I found the UI very easy to comprehend, and all commands and functions that I wanted to make use of were available. Most of my hull modelling experience is in sheet metal, and PolyCad has the option of producing a bi linear surface. This is something I really need to explore further. And an upcoming feature will be the inclusion of developable surfaces, which is right up my alley and something I am following with interest.

I also really enjoyed reading his B Eng dissertation ‘Parametric generation of yacht hulls’ particularly his summary of the different methodologies for hull generation, and their history. I have yet to delve into his PHD Thesis though!

This type of modeling is the mirror image of what I have most of my experience in, namely parametric solid modelers, and as such allows you to generate forms that solid modelers can only dream of. I would like to believe that my background as a sculptor, combined with my knowledge of correct 3D modelling would make me a perfect fit for this environment. I have familiarized myself with PolyCad, and look forward to expanding my use of it in the future.

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