How to design basic construction elements in the sectional drawings

This article covers the initial design phase for a ship's hull construction within MasterShip. After defining sectional drawings and the assembly, the next step is designing the basic construction elements. These elements, such as bulkheads and girders, form the foundation for the entire hull structure.

By designing these primary components first, shipbuilders establish a reference point for incorporating secondary elements like stiffeners and brackets. This process essentially lays the groundwork for defining the entire framework of the vessel.

Did you know? The largest single piece of flat steel ever produced for a ship was for the RMS Titanic, weighing in at a staggering 48 tons! This massive plate formed part of the ship's inner bottom.

How to design basic construction elements in the sectional drawings in MasterShip

This video shows how to make basic construction elements in the sectional drawings in MasterShip from the software perspective. Next to that, we have listed some of the best practices in the shipbuilding industry from the engineering perspective, and how MasterShip functionalities apply below.

• Specifying the thickness direction: Specifying the right thickness direction for plates is vital. An error here can lead to rework or structural issues later. Typically, the frames and longitudinals point towards the midship and the horizontals up.

In the MasterShip Assembly Manager (SHIPASSEMBLYMANAGER) you can set and modify the thickness direction per sectional drawing easily.

Additionally, the MasterShip Workshop Assistant (WSA) can check for collisions of solids from sectional drawings with hull plates. These might arise due to an incorrectly specified thickness direction.

• Drawing the part outline parametrically: The size of your bulkheads, decks, and other elements needs to be precise and consistent with the requirements from a.o. classification and engineering. MasterShip offers tools for drawing the parts, such as SHIPCREATEPARTS. MasterShip offers a functionality called Template Orientated Modelling (TOM) for parametrically modelling and updating parts.

• Drawing stringers: Depending on the situation, stringers can be drawn as plate parts (described above), or as stiffeners. If the stringers are yet defined in the shell expansion drawing, and desired to be drawn as stiffeners in 3D, then it can be convenient to draw them directly in the 3D hull model, and not in a sectional horizontal drawing. See also the article how to design stiffeners. 

• Saving time and ensuring consistency: With the command SHIPCOPY it is possible to copy parts from one frame drawing to multiple other frames, even when the shape of the frame changes. Doing this effectively requires the parts to be drawn using 'tagged line entities' and be constructed using SHIPPARAPART.

Another time-saving tool is the command SHIPMIRRORCL. It can be used to mirror parts around the centerline. Note: The AutoCAD command MIRROR is not to be used for this purpose. SHIPMIRRORCL ensures that the mirrored parts and stiffeners are saved in the database, and stays linked with the original part. A change to the original part will automatically update the mirrored part.

• Consider external components: A ship consists of multiple disciplines, with the construction just being one of them. All these disciplines should fit together. External components, such as piping systems, engines, etc. directly influence the construction design. Importing external components, greatly helps with designing a compatible construction, and can also help a lot when checking for consistency and clashes. 

• Checking for consistency: Drawing parts in a sectional drawing gives you a 2D view. Of course, the ship's construction is three dimensional, and the construction should be consistent in all three dimensions. With the function SHIPSECTIONS you can get the outline of solids from other sectional drawings in your current drawing. For example, with this function, you can easily identify a stringer passing a frame drawing.

You can also visually check the 3D construction in the assembly file (assembly.dwg). Also, the MasterShip Workshop Assistant (WSA) offers a 'clash detection' for solids. This way, you can identify if there are plates, stiffeners, equipment, etc. intersecting each other.

Adding properties to your MasterShip parts is also an important part. These properties typically helps to streamline shipyard logistics, and also improve communication between draftsmen and involved parties. here is how MasterShip supports:

• Using naming conventions: Clear and consistent names for your components make everything easier to streamline shipyard logistics. MasterShip assigns a unique ID (PosNum) to each part when it's drawn. The decoding list can be found in the MasterShip WMD.

You can also set up your own naming rules for assigning a PosNum using the MasterShip Organiser (General > Identifications) to match your shipyard's standards.

Expert tip: It is possible to modify the part data block in MasterShip to your own standards. See this article: Modifying the part data block.

• Assigning production units: Production units can be set and modified using SHIPPRODUCTIONUNITS. When a production unit is defined, it can be assigned to a part while creating it. Or afterwards using SHIPEDITPARTDATA. These numbers help to improve your shipyard logistics

• Assigning material: The material of parts is set as a default in the MasterShip Organiser for each project, but can be modified per part using SHIPEDITPARTDATA. Assigning this information comes in handy further in the process, with nesting an making reports.

Other considerations

When drawing the construction, it should meet the technical requirements and standards from the classification society, engineering department and shipyard. The construction model has to fulfill all the specified requirements, for adequate building and later practical use of the ship.

This is expert knowledge. A draftsmen is usually not able to be aware of all the requirements specified. Therefore, reviewing of the 3D model by the party that supplied the requirements, or other relevant stakeholders, is very important. To have your model reviewed, it is necessary to export and share your 3D model with the right tool.

Output and next steps

Following these best practices ensures a solid foundation for subsequent stages of shipbuilding. After defining the basic construction elements, the next steps involve: Designing the detailed construction of the ship's hull, Making arrangement drawings, Performing weight calculations.