NURBS Surfaces

Create and manipulate NURBS surfaces with control point snapping, knot insertion, degree raising and review feedback from hull contours, curvature and upright hydrostatics. (Read more...)


Define surfaces using X-Topology to represent hull forms directly or using lofting techniques to explore fair shapes before produce the surface. Build curve networks with dynamic snapping and shape constraints. (Read more...)

Point Clouds

Import in Point Cloud data to visualise and extract geometry by snapping. Fit and smooth X-Topology Curves using Least-Squares. Confirm the accuracy of surfaces against the point. (Read more...)

Intersection and Fitting

Fit B-Spline and X-Topology Curves to Point Clouds and other curve or surface geometry to build up surface definition which matches the original representation or apply smoothing to improve quality. (Read more...)

Hull Form Generation

YachtLINES and ShipLINES quickly generate hull forms using parametric control of main dimensions and volumetric properties. IntelliHull extends this by introducing style control using design curves. (Read more...)

Geometry from Images

Import line art and scanned plans as images, assemble them in 3D and digitise geometry without the need for additional hardware. Build up hull surfaces from the plans and validate against the imported image. (Read more...)


Interactively Scale, Reflect, Rotate and Translate all elements. Transform Hull Definitions using geosim, 1-Cp, Lackenby and McNaull methods while comparing shape and hydrostatics. (Read more...)

Hull Sections

Import coordinate data as sections, change, manipulate and convert into other representation. Respace points and sections. Generate indicative Lines Plans. (Read more...)

Import and Export

Import geometry from various graphic and CAD file formats. Extend, modify or remodel by fitting to the source geometry before exporting. (Read more...)


PolyCAD allows you to create, manipulate, import and export geometry for yacht and ship yacht design. In its development, now over more than 20 years, it has explored opportunities for rapid and accurate curve and surface modelling to support the hull surface design. Starting out as an editor for simple hull section geometry, it took on the challenge of surface modelling with NURBS and Parametric Hull Generation. Today, X-Topology goes beyond most hull surface design software by allowing both the representation of complex, multi-patch surfaces using Design Intent and introducing methodologies that allow hull forms to be designed faster and more accurately that typical surface design techniques. It's an exploration of the art in a modern Windows executable.

PolyCAD is free. Free to download, free to register but also free from the commercial pressures that limit innovation in this specialised area of design. PolyCAD is not about just-enough capability to perform a task for maximised cost. This allows alternative approaches of user interface and hull surface design to be explored without reference to a return on investment. PolyCAD is developed for the love of the art of hull design.

Hull Surface Design is not easy. PolyCAD has a user interface which has been crafted to support design within the constraints of a 2D screen and mouse movements. Snapping, constraints, transformations, geometric and hydrostatic analysis are all tools available to the user during the design experience. However, the challenge is in design itself. Using your expertise to craft shapes can be difficult especially when you are learning the process. Take your time to learn the tools and understand the processes involved. Few people in the world master the art of controlling mathematical representations of the shape of planked wood or steel plate and it's always rewarding see a smooth shape after a couple of hours of being in the design 'zone'.

What's New...

After a couple of years on the drawing board I've finally released the website. Some of the articles were written over the last 10 years but never published because the old format didn't lend itself to this kind of information. PolyCAD is now updated to version 10.1. This sees the public release of the Point Cloud tools as well as the new surface modelling and analysis updates. Following that, I'll need to get it into the latest Delphi compiler.

If you want to download the latest version of PolyCAD and use it on the same computer you're presently using you do not need to register again.  Find out more in downloads.

Hull Surface Design

PolyCAD provides surface modelling capability for hull forms using mathematical curve and surface entities. While X-Topology Surface modelling provides capability to design the most complex ship surfaces PolyCAD starts by providing the powerful capability to manipulate basic elements such as Polylines, NURBS Curves and Surfaces and Hull Sections because we use these elements every day in drawings, 3D models and exchanges between modelling and analysis software. But if we're going to design can be a slow and unproductive process to build a hull using these elements. If we need something fast Parametric Hull Generation can often provide that will give insight into the design challenge without too much definition time. Then if we're going to embark on a full design where we want specific control over areas of curvature we can turn to X-Topology to create a surface definition rapidly using supporting methodologies like Lofting to produce a fair shape.

Hull Surface Geometry Reconstruction

The reality of our work is that it is rare for Naval Architects to be designing beautify hull surfaces every day. In fact, far more time is spent keeping existing vessels safely afloat. Hull definitions are not always in the format we'd like and redefinition must frequently be under taken. PolyCAD supports this process by introducing conversion and fitting techniques to change the format of geometry or author new elements based on the shape of others. A wide variety of import and export file formats are supported. PolyCAD also supports the import of images allowing scanned 2D documentation and plans to be projected in the design environment. Point Cloud surveys can be imported into the design environment allowing hull definitions to be created for vessels where documentation may be unavailable. X-Topology provides a range of fitting tools which reference all other geometry types including Point Clouds allowing a hull surfaces to be generated with respect to geometry quality and accuracy to the original source data.

Naval Architecture & Analysis

Without analysis it's impossible to gain insight into how designs will perform when they reach reality. PolyCAD implements a range of analysis tools to evaluate design performance. These tools are somewhat different to those found in the professional applications as they aim to teach and provide understanding into the principles involved. From basic geometric information, surface curvature, hydrostatic, stability, and soon weight estimation and hydrodynamics can be used to evaluation your design performance and direct your next decision.

PolyCAD on Youtube

A dedicated Youtube channel hosts videos that have been produced to help explain and teach the software. Several videos on X-Topology have been consolidated on this page here.

PolyCAD on Facebook

A PolyCAD Facebook page is available although created it was used for promotion. I shall be posting stuff there as PolyCAD develops as it's much easier to add to than a webpage. Feel free to comment and ask questions.