SHIP DESIGN COMPLEXITY
Prior to commencing with any training related to Marine Engineering, especially the office-based position of a Marine Engineer related in the design of ships, a distinction needs to be made between the general responsibilities of the Marine Engineer versus that of the Naval Architect and their applied knowledge. By making this distinction it also provides a good opportunity to indicate the complexities of ship design.
Firstly, Marine Engineering is concerned with the design, construction, installation and support of the systems and equipment onboard marine vehicles (ships / vessels / boats / offshore installations), with particular emphasis on propulsion and control systems, while Naval Architecture is concerned with ship safety, ship performance and ship geometry.
To visualise the difference between Marine Engineering and Naval Architecture, please refer to the below table:
As you can see, Naval Architecture is more concerned with the design of the geometry in terms of hull form, materials and structure, the ship’s safety in terms of ship stability, floatation, trim and general safety, as well as ship performance in terms of resistance and propulsion, seakeeping and propulsion. Marine Engineering’s sole focus lies in the systems to be used on-board the ship, which is generally categorised in one of three main categories, namely:
- Propulsion Systems
- Auxiliary Systems
- Control and Management System
Also, take note, in the top row of the table, the various aspects regarding environment, a suitable ship type to conduct specific operations, as well as the cost associated with the production and operation of such a vessel, that both Marine Engineers and Naval Architects must consider throughout the entire design process of a ship.
Every ship, no matter how small or large, presents a complex system of systems. Ship design is a synthesis of many engineering and non-engineering disciplines, meaning that personnel with various qualifications and skills need to work together to ensure that all systems eventually come together in a harmonious fashion. Therefore it is sensible to say that a successful optimal ship design presents a well-solved jigsaw puzzle.
Using the SFI Group System is an ideal way to indicate the complexity of a system of systems.
The SFI Group System, of which the lowest levels are shown in the table below, was first released in 1972 as the result of a research project undertaken by the Ship Research Institute of Norway (SFI: Skipsteknisk Forskningsinstitutt). SFI’s breakdown structure is the most widely used work and equipment breakdown structure used in the commercial shipbuilding industry.
Naval establishments make use of the Expanded Ship Work Breakdown Structure (ESWBS). The main difference between ESWBS and SFI is the addition of specific system groups for Command and Surveillance and Armament Systems. Both System Group methods serve the exact same purpose of classifying specific and related systems into a single group, allowing for better control of the design process. Take note that all systems shown in the tables below, only constitutes the 1st Level. These system groups are then further broken down to a 6th Level, also known as the “nuts and bolts” level.
SFI Level 1
ESWBS Level 1
Both the SFI and ESWBS are used by shipping and offshore companies, navies, shipyards, consultancies, software suppliers, authorities and classification societies as a means of specifying each system that can be found on-board a ship. Each coding system can be broken down into considerably more sub-levels, even up to nut and bolt level as stated earlier.
A prime example of the complexity of ship design is shown in this photo of a semi-submersible being transported by a dry tow vessel. The amount of design that goes into achieving such a feat is immense.