Trans RINA, Vol 156, Part C1, Intl J Marine Design, Jan -Dec2014
Research by DeNucci on “Knowledge Capture”[10] with the development of a visual interface as a support for dialogue between the stakeholders would prove useful in this step; however, it is not known how widespread is this interface in the industry. In Section 4.1 we propose a low-tech tool that may also support
this dialogue. Concept development and
exploration, as described by van Bruinessen et al. [11], is a way of exploring the ship’s design space at an early stage. However, this exploration is based on a fixed system of components and requirements, hence
preventing the “unknown” designs.
3. Designing the ship: the historical “design spiral” method [12] is both the most commonly used, and the most commonly criticised method. The main criticism is that it is a good model for the detailed engineering phase, after the design choices are made: “this model easily locks the naval architect to his first assumption and he will patch and repair this first and only design concept rather than generate alternatives”[13]. System engineering is more recent and has gained traction in the industry. The main criticism (from the same previously cited author) is that by cutting the design problem into blocks (systems, sub-systems, sub-sub
systems, etc…)
innovative solutions can only happen inside, and not in between, the blocks, which severely limits the chances of obtaining an innovative design overall [13]. This illustrates that it is crucial to include what occurs at the interfaces between different actors and different
steps in the design process, and that
supporting the dialogue between different experts from different disciplines is a need that must be covered by the design process to bring local innovative solutions up to the
overall design
solution. Formal design optimisation, facilitated by an increase in computing capacity, is attempting to address this problem in a horizontal, or “holistic”, way. A multi-objective
optimisation problem is
defined, and it is supposed that the solution satisfies a wide set of transverse requirements [14]. However, the usability threshold for this method is very high (both in terms of hardware and software), and it can only provide solutions to requirements that can be mathematically formalised. “Soft aspects” of design, such as the confidence of the owner that the ship will satisfy their requirements are difficult to integrate in this process. Experience at DNV GL in facilitating design processes shows that the selected ship design is most frequently not necessarily the design with the best “scores”, but rather the design that all the actors like best.
4. Building the ship: at this stage, the main design is specified in a comprehensive design specification, but a great deal of detailed design remains to be done. The quality of the detailed design and the quality of the execution of this design in terms of, for example, steel workmanship is absolutely crucial to the quality of the delivered ship. Accompanying
find of “alternative” or
the design in its transformation from a purely analogue/digital form (drawings and 3D models) into a physical form (steel structure) should also be part of the designer’s job. This is known as “design for construction” and has been documented in Bertram [15] and Lamb [16], for example, with a particular focus on what hull shapes can actually be built, and at what cost. Experience at DNV GL shows that the same
design specification can
produce 10 ships with different performances in terms of fuel efficiency, and research is ongoing to provide support to shipyard, class and owners in identifying areas of attention for construction, as well as construction tolerances [17]. For example, number, position and thickness of weldings in the bow area, positioning of the bilge keel, orientation of the bow thruster grids, anodes, rudder alignment, etc. The implementation of such added precautions again must cater for the resources and limitations of each actor involved in the process: how to communicate the effect of local turbulences generated by a weld that is 5mm too thick to a steel welder who has no background
in hydrodynamics? How to
communicate the need to grind down this weld to the steel welder’s manager, who is focused on keeping the project on schedule?
5. Ship in operation: most published methods agree that the ship should be designed for a specific operation, and that
data from past or formal design optimisation future
operations are fundamental in the process. This is especially true of
methods, where the ship’s operating profile is a constraint on the optimisation problem [14]. It would be interesting to see how many designers follow their design in operation, to assess whether they perform according to specifications, and include this information in their next design. This requires having good systems in place (both procedures and technology) to measure the performance of the ship in operation, and competence in data-mining to extract meaningful data from the large quantities produced, day after day of operation. Closing the loop
from operation back to design is
challenging; for example, it would require obtaining the insight of the navigating crew, which is not a common practice in ship design.
6. Decommissioning: this step has not yet been studied. There are most likely many possible improvements to be made to the individual experiences of the actors involved in this process.
3.2 COMPUTER-AIDED SHIP DESIGN
Computer-aided ship design (CASD) is the major tool used in ship design. It is powerful in accelerating the design process by optimising the execution and coordination
of successive engineering tasks,
highly
and
assembling them into an automated decision-making process. As such, it is not a tool that is very well suited to a design space exploration, and early movers and
C-32 ©2014: The Royal Institution of Naval Architects
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