The Hull Form and Naval Calculation modules cover the initial phase of the ship hull design process. They are used to determine all main characteristics of a future ship. The Hull Form module functionalities are:

• Hull form modeling from a sketch or by variation from the archive of forms
• Tools for fairing curves and surfaces based on shipbuilding experience
• Transformation of existing hull forms to meet the required L, B, T, displacement or LCB
• Calculation of basic form properties (displacement, KM, VCB, LCB)
• Extended features for creation and modification of the hull form with NURBS curves
• Surface patches creation with NURBS curves mesh
• Automatic generation of building frames
• Hull form details definition (e.g. mooring equipment, rudder, etc.).
• Intersection of hull form with arbitrary planes to obtain frame lines, waterlines, etc.

The hull form is designed in two ways: from scratch, creating the characteristic plane curves (frames, waterlines, buttocks, ...) and using the process of fitting and fairing to get the desired form of the hull surface or by using the library of customized hull forms which can be modified to meet the new main characteristics of the hull. Both ways include a rich and sofisticated set of tools for working with NURBS curves and surfaces.

Tools for fitting and fairing NURBS curves and surfaces are based on an extensive shipbuilding experience of many engineers and designers involved in the process of the ship design.

The main functionalities for fitting and fairing curves are:

• Generating smooth curves through interpolation (knot) points or with control polygon
• Tangency constraints at any point of the curve
• Creating NACA profiles as NURBS curves (rudders, wings, ...)

Curve modification functionalities include:

• Interactive moving one or more knot points
• Interactive changing tangent direction and/or magnitude at any knot point
• Adding/deleting knot points on a curve
• Displaying needed curve information (knot points, tangents, inflection points, curvature,...)

The NURBS curve mesh define the boundaries of surface patches. Across patch boundaries C1 continuity is preserved. There are various visualisation methods available (shaded, wireferame, Gauss curvature, ...).