The fore ship is represented by three patches of the surface. The curvilinear surface of the body itself is framed by a triangular section of the flat bottom and a quadrangular cylindrical section of the surface of the flat side, which passes into the vertical part above the knuckle line. This is a typical fore ship splitting scheme. In this case, the presence or absence of the bulbous bow of the vessel does not play a significant role. In any case, the curved surface will be only one.
The parallel midbody is also represented by three surface patches, which are a continuation of the surfaces of the fore ship. The surfaces of the side and bottom are respectively flat, and the surface of the bilge is cylindrical.
The surface of the aft ship can be divided into two groups: the surface of the main body and the surface of the skeg.
Main body surface consists of three patches. Note - flat bottom line in for this type of vessel in aft ship is not defined.
Skeg surfaces is just extruding of skeg bottom profile along skeg line in CL.
For make a solid hull surface we use intersection and trimming of these surfaces. It gives as additional freedom for main body and skeg surfaces modification.