IntelliHull aim to integrate the three main techniques used to develop hull forms.

• Transformation from a parent hull form.
• Manual development of a hull surface from scratch.
• Parametric hull development techniques.

The Intellihull approach takes the ideas behind parametric hull generation and opens it up to allow the user to manipulate the internal curves. This allows the shape of the hull form to be controlled interactively by the user rather than numerically. Parameters can be used to transform the shape of the hull rather than specify it explicitly. The arrangement allows for a lot of flexibility is conducted as the hull can be manipulated both parametrically, controlling dimensions and interactively to control shape. Ultimately, this makes the hull design experience much more productive.

To implement these ideas a framework is introduced which separates the geometry the user manipulates from the hull surface definition geometry. This separation provides a space where the software can analyse the user’s definition and determine how to produce the hull surface geometry. Additional ways of defining the hull form may be introduced such as using mark-up or attribute information attached to the user’s definition which informs the software to produce a certain effect in the hull surface such as a knuckle or tangents. Furthermore, the software may determine that the user has not provided enough definition geometry to complete the hull surface and may supply its own based on what the user has provided. Consequently, unlike most hull design tools where the user is primarily concerned with building up enough geometry to create a fair surface, the user can start with a hull surface defined by a limited amount of information and refine it further as the design becomes more detailed.

IntelliHull introduces the concept of hull form topology in a simple design tool, i.e. single surface, where ordinarily the user would only come across this in the design tools orientated toward detail ship hull form design. The ideas of topology can applied to the hull form in regards of the way geometric definition is arranged and what part of the hull surface it controls. Often, the underlying structure of hull form definition geometry is very similar between vessels of the same type differing only in the geometric location and local features. The first version of IntelliHull (PolyCAD 6-7) uses this fact to automatically identify the role of curves in the design. In PolyCAD 8, this feature is removed because it was found that it is difficult for the software to recognise these features requiring complex code whereas the human user is much more adapted to identifying patterns. IntelliHull in PolyCAD 8 introduces a way of defining the role the curve plays in the surface through attributes. Having said this, topology is a powerful tools and the next stage of development, X-Topology, exploits is capability more extensively.

As mentioned at the start of this section, the underlying approach used by IntelliHull to generate the hull surface definition is very similar to that of ShipLINES. Curves are used to define the bow profile, midship section, transom and the forward and aft ends of the parallel middle body. Curves are also used to define surface tangency. Constraint tools are used to arrange the control points of the curves to introduce features such as straight sections, blends and knuckles. The constraint tools can also be used to restrict the curve geometry to a plane and to base the shape of a curve on another (offset constraint). The offset constraint can be used to control the shape of the forward and aft curves defining the parallel middle body based on the shape of the midship section, for example. Once the main surface has been generated, the framework allows the surface definition to be refined allowing a bulbous bow appendage to be added using a warping operation.

Subsequently, parameters can be used to modify dimensions or change the hydrostatic characterisics of the surface by iteractively adjusting the fullness of the hull form in the bow and stern portions.

The process used to create an IntelliHull definition is illustrated in this example.

bhull.geo

bhull+nobulb.geo

bhull+sponson.geo

flathull.geo

dhull.geo