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General arrangement optimisation: A new approach to ship design

Artificial intelligence has for decades been rumoured to revolutionise ship design and change the ways we work forever. However, apart from improving Computer-Aided Design (CAD) tools, the creation of general ship arrangements is relatively the same as in the 1980s.

30 June 2021

Coastal Infrastructure Commercial Maritime Defence and Security Energy and Resources Water Management

General Arrangement Optimisation: A New Approach to Ship Design

One research team at University College London (UCL) and University of Southampton is helping to change this by exploring the use of Genetic Algorithms in ship design. Their highly interactive genetic algorithm-based layout exploration method enables naval architects to make important decisions in a hybrid design process.

Developing a suitable general arrangement is a critical part of ensuring the successful design of all ships, from superyachts to aircraft carriers. How different spaces, such as bridges, crew quarters, control rooms etc, are sized and located is fundamental to guaranteeing safe and effective operations. It is a complex, time-consuming and inherently iterative part of the design process since many different, and very often conflicting, requirements must be balanced within the constraints of the vessel, while ensuring that all aspects of the operations and human factors are considered.

A high-level general arrangement is considered for the first time in the conceptual phase of the design process, referred here to as Early Stage Ship Design. The main purpose of this initial phase is to design several alternatives of the overall layout, which are then considered to assess their cost and performance trade-offs with the aim of clarifying design requirements.

The many downsides of a laborious all-manual design approach combined with the development of affordable computational power has urged researchers to start developing methods and tools that can automatically produce design options. Early examples of automated arrangement systems often focus on the “box packing” methodology in order to find the most efficient use of space for the given requirements. While they provide an effective use of space they may struggle to create a realistic or operable design. It is possible to add specific design constraints but this can also be a laborious and time consuming process and reliable results are not guaranteed.

“Genetic Algorithms will not replace the role of a Naval Architect, but they will enable them to do their job better, providing them with a range of design options and their associated compromises”.

Work conducted by Bojan Igrec, Rachel Pawling and Giles Thomas of UCL in collaboration with Adam Sobey of The University of Southampton is looking to change how these design tools are structured in order to create a fast and reliable output.
The method utilises a genetic algorithm based optimisation tool to rapidly generate and evaluate a set of general arrangement options. Rather than attempting to create an optimised design in one step, the toolset splits the design process into discrete sections to imitate the steps taken by an experienced human arrangement designer. The method is multi-level and strictly hierarchical, whereby the vessel is divided into a set of sub-units which are used as “containers” for allocating and arranging lower-level units.

First, the ship is split into decks (the highest level units) to calculate the available volumes and areas. Next, system routings and passageways are mapped-in to provide a first level view of how the compartments can be arranged. The model is then divided into segments connected by the network of major routes in the so-called segmentation process, which takes into account requirements for watertight bulkheads. Next in the hierarchy are units of compartments that form zones, and separate compartments which are being allocated and arranged within segments in zoning and arrangement steps, respectively. Finally, utilising a database of ship compartment relationship mapping, the algorithm uses scoring solutions to assess thousands of different arrangements and configurations. Points are deducted for wasted space and/or overlapping compartments, as well as for placing compartments in undesirable locations in relation to themselves or other compartments.

The key is to allow for dynamic node-based segmentation and choosing the right set of rules. Instead of rigidly sticking to the initial mapped arrangement it allows the computer to explore the solution space and explore the options of moving boundaries and watertight bulkheads.

If these tools can be developed, they will enable the human user to rapidly assess and compare the different design solutions available to them as part of a parametric analysis. By providing greater information and options analysis it enables the naval architect to minimise design risk and provide clarity on the design route in a shorter timeframe. Arguably one of the most important parts of the entire toolset is the inherent knowledge and database of ship design arrangement scoring. This uses historical data, design rules/regulations and user surveys to create a matrix of the different ship compartments and how they should be placed within the ship and relative to each other. This scoring matrix can be used in its own right as a tool to objectively score and grade any general arrangements fed into the system; a process that is famously subjective and relies on expert knowledge and experience.

Professor Giles Thomas, BMT Chair at UCL explains, “Genetic algorithms will not replace the role of a Naval Architect, but they will enable them to do their job better, providing them with a range of design options and their associated compromises.”
He adds, "There is no such thing as a perfect ship design. There is always compromise and trade offs to be made between requirements; the General Arrangement Optimisation Tool being developed by UCL and BMT enables these options to be compared and assessed in an objective manner.”

Their research is supported by BMT and while the toolset is very much still in development, initial trials show great potential for use in Early Stage Ship Design exploration work. If you would like to know more about their work and how BMT are using their toolset to make their ship designs better, faster and more affordable then please get in touch.

About the Author

Professor Giles Thomas

BMT Chair of Maritime Engineering, University College London

Professor Giles Thomas

BMT Chair of Maritime Engineering, University College London

Giles Thomas is BMT Chair of Maritime Engineering in University College London’s Department of Mechanical Engineering. Giles has been at UCL since 2014 but before then he was working for the Australian Maritime College at the University of Tasmania for nearly 11 years. A naval architect, his research focusses on the performance of ships, boats and offshore structures. He is a Fellow of the Royal Institution of Naval Architects (RINA) and a Chartered Engineer (CEng – Engineering Council of Great Britain).
He currently leads a team of researchers at UCL investigating a range of different areas, from data analytics on full scale ship measurements to implementing virtual reality in the ship design process.
He is a three-time recipient of the Medal of Distinction from the Royal Institution of Naval Architects and was awarded the Vice Admiral E. L. Cochrane Award in 2019 by the Society of Naval Architects and Marine Engineers. 

Jake Rigby

Research and Development Lead, BMT

Jake Rigby

Research and Development Lead, BMT

Jake Rigby is the Research and Development Lead, responsible for the portfolio management of internal research projects in defence. This covers a broad range of research topics from ship and submarine design to digital twins and artificial intelligence. Through this role he leads the horizon scanning activities of BMT, tracking external trends and developing the reactive technology roadmaps. He is always on the lookout for the next emerging technology that can revolutionise or incrementally change the way we and our customers operate. He is a chartered engineer and Member of the Royal Institute of Naval Architects originally training as a Naval Architect specialising in ship signatures before his current role of R&D lead. He is a proud member of range of different industry research and technology forums; one of which is the recently formed Maritime Research and Innovation UK  (MarRI-UK) for which he leads the  “Clean Maritime” research theme. This is an area he is particularly passionate about, investigating how industry, government and academia can work together to provide an economical and sustainable future for the maritime sector.
Jake is also responsible for Academic Engagement at BMT. In recognition of his work to progress Academic Engagement in the maritime sector he was recently awarded the title of Honorary Associate Professor at the University of Exeter, and continues to engage in a range of collaborative research projects.

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