The shell expansion drawing containing basic construction

The shell expansion drawing including basic construction shows the hull shape, laid out as an expanded view, together with the basic construction of the ship. Besides hull geometry and strake layout, it marks the primary structural members intersecting with outer shell. This includes main frames, longitudinal girders, bulkhead boundaries, major openings and basic plate thickness zones. It is not the complete production drawing, but a preliminary structural layout drawing for basic design. 

The basic design in the shell expansion is amongst others used for preliminary hull plate arrangement, classification preliminary approval, onboard archive, hull survey, thickness measurement and damage location during dry docking. It is not suitable for plate cutting and fabrication.

In MasterShip it is drawn in the model-space, and it is usually presented as a paper-space drawing using the MasterShip templates. This drawing is developed on the basis of empty shell expansion.

Figure 1: the shell expansion drawing including basic construction

Which SHIP-commands apply?

• Exporting this drawing: for example to PDF-format. Follow the steps in this article: Making paper-space views using MasterShip's templates.
• Consistency check with the 3D construction model: By including the shell expension drawing in your assembly file (assembly.dwg), you will get one comprehensive overview of both the shell expansion and the 3D construction model in one file. This allows you to visually check if they are consistent. If you run the AutoCAD-command XREF, whilst having the file assembly.dwg active on your screen, you can add the shell expansion drawing to this view.

How can it be used?

The shell expansion with the basic construction design can be used as follows:

• As a base for 3D structural modelling and making the detailed design: It locks the relative positions between outer shell and main structural members. This information is imported into the 3D model as the structural baseline. In the later detailed design phase, secondary stiffeners, brackets, small openings, plate marking and bevel details will be supplemented.
• As a base for defining the seams & butts.
• Preliminary strength & rule compliance check: Used for basic design review and classification society submission. It verifies the compliance of sheer strake, flat keel plate, local reinforcement and shell thickness distribution with classification rules, and identifies potential structural non-conformity at early stage.
• Preliminary evaluation of fabrication and block division feasibility: Locate major structural intersections on the flattened shell surface, to assess manufacturability of curved plates at bow, stern and bilge regions. Carry out preliminary block division planning.
• Integrated layout of shell plating and main hull structures: It visually shows the relation between outer shell strakes and primary structural components. Check whether plate seams coincide with high-stress areas such as frames, girders and bulkhead connections, and optimize the layout of strakes and structural members to satisfy strength requirements.
• Communication basis among design team, shipowner and shipyard: It provides an intuitive 2D flattened view of hull outer shell with main structures, facilitating technical discussions on structural arrangement, plate thickness scheme and construction concept in basic design meetings.
• Preliminary structural weight, centre of gravity and steel consumption assessment: Compared with empty shell expansion, this drawing incorporates basic structural members attached to shell plating. It can provide more accurate steel weight, LCG and VCG estimation, and support preliminary steel take-off for cost evaluation and quotation.