Design rationale is a promising way of capturing design decisions and considerations for later retrieval and traceability to improve collaborative design decision-making. To achieve these perceived benefits for early-stage complex ship design, this paper first elaborates on the development of a proof-of-concept design rationale method. The method aims to aid ship designers in the continuous capturing and reuse of design rationale during the collaborative concept design process. Second, the setup and results of an experiment conducted with marine design students and with experts are discussed. This experiment shows how the developed design rationale method benefits collaborative design decision-making such that it leads to improved insight into design issues across the design team during a single design session.@en

This paper presents a new design rationale methodology to support collaborative design decision-making during early stage complex ship design. The nature of collaborative design is described and the need and key challenges of design rationale capturing and reuse are identified. Subsequently, the methodology is developed to overcome these key challenges. A primary characteristic of the methodology is it’s integration with design tools to reduce intrusiveness and enhance usefulness during collaborative design sessions. Finally, a case study was used to demonstrate the usefulness of the developed design rationale ontology, a critical step in providing designers an improved capability to capture and reuse design rationale during collaborative design decisionmaking.@en

Generating detailed warship layouts is crucial to check technical feasibility and performance consistent with emergent requirement elucidation during early stage design. However, generating feasible detailed layouts is a complex and time consuming task. Even today, detailed layout plans are often manually drawn using CAD software, taking up to 150 work hours to complete a single feasible layout plan, as found by the Netherlands Defence Materiel Organisation (DMO). As a result, the number of layout variations that can be generated and analysed is limited. This typically means that further detailed layout generation is postponed, increasing the risk of costly sizing and integration issues later in the design process. Therefore, a method that enables rapid insight into layout sizing issues is required. This paper elaborates on the mathematical working mechanisms of the WARship GEneral ARrangement (WARGEAR) tool, that has been developed to support naval architects in detailing ship arrangements to space level in a matter of minutes. Contributions are: (1) a probabilistic staircase placement algorithm, (2) a network-based approach combined with probabilistic selection for allocation of spaces to compartments, (3) the use of cross-correlation to quickly arrange spaces, and (4) a ‘carving’-based approach to ensure connectivity. A representative WARGEAR application case study is presented. This test shows how WARGEAR is able to confirm the feasibility of future warship arrangements at a high level of detail within minutes.

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The development of concept designs during early warship design stages is essential to inform stakeholder dialogues on technical feasibility, affordability, and risk. One of the key aspects of warship concept designs is the layout of systems in the overall arrangement. The adoption of real-time design processes, such as concurrent design, require naval architects to use layout design tools in a more dynamic setting than during traditional design review session-based design processes. This paper investigates how ship layout design tools can be used in a real-time manner. It does so by considering the arrangement problem of allocating systems to compartments, subject to available and required area, global system position preferences, and preferred relative system positions. An existing ship layout design tool, WARGEAR, is extended to consider global and relative system constraints, and is integrated in a proposed method for the allocation of systems to compartments. Furthermore, a novel two-item correlation metric is developed to support designers in the analysis of the, typically large, design space. The metric can be used to identify conflicts and trade-offs between design parameters, as well as promising combinations of design parameters. Two case studies (8 and 89 systems respectively) are used to demonstrate and evaluate the proposed method. Based on these case studies, the calculation time or accuracy of the allocation method does not seem to be the main issue for collaborative design decision-making. Indeed, most effort is required for the analysis of the generated concept designs. Since this is not a problem as such, the real-time use of automated design tools to evaluate the impact of proposed design changes seems to be a promising way to enhance the effectiveness of collaborative ship layout design sessions.@en

Vulnerability reduction measures are taken during the early stage distributed ship system design process to ensure the availability of the required systems in a damaged state. Traditionally these vulnerability reduction measures are based on design rules or best practices resulting from past experiences. Therefore, the measures are not per definition applicable for future warships, as both the system concepts and operational environment changes. Recently developed vulnerability assessment methods are able to determine the vulnerability of a design early in the design process. With the integration of these methods in the early stage design process, the results of the analysis can be used to generate less vulnerable distributed ship system designs. This paper proposes an integral and holistic approach to optimisation of the design variables and distributed networks as these are becoming increasingly interdependent. The result of this approach is a model which generates distributed ship system designs consisting of component positions, a topology and routed connections based on a pre-defined system configuration and constraining physical architecture. Five testcases were conducted using this model, showing the necessity of the integral and holistic approach as the extent to which the contemporary design rules are implemented depends on the network complexity and operational environment.

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Naval ships are designed to operate and survive in hostile environments. As such, vulnerability reduction is a major topic of interest during the design of a naval ship. For modern naval ships the vulnerability is largely determined by the design and layout of distributed systems. The vulnerability of these systems needs to be assessed early on, as design decisions made in this stage are decisive for the vulnerability of the final ship. Various early stage methods for assessing vulnerability exist, but a clear structure on when to use what types of methods, how these methods relate to each other, and how these methods provide relevant answers, is still lacking. To address this gap, this paper introduces a framework for early stage design of distributed systems, in the context of vulnerability reduction. This framework supports in choosing the right vulnerability method at the right design stage. The framework considers an operationally oriented systems perspective on vulnerability, and a physically oriented ship perspective. In addition to that, early stage design is subdivided in concept exploration and concept definition, which have different purposes and contributions in the design process. The framework provides examples of methods that can be used to investigate vulnerability for the various perspectives and design stages. These examples consider methods that have been developed by joint Delft University of Technology (TU Delft) and the Netherlands Defence Materiel Organisation (DMO) research efforts, as well as other methods. Opportunities and challenges for integrating these methods between themselves and in the design process in general are discussed.@en

Vulnerability reduction is an important topic during the design of naval ships because they are designed to operate in hostile environments and because their on-board distributed systems are becoming increasingly complex. The vulnerability needs to be addressed in the early design stages already, in order to prevent expensive or time-consuming modifications in later, more detailed design stages. However, most existing methods for assessing the vulnerability are better suited for more detailed design stages. Furthermore, existing methods often rely on pre-defined damage scenarios, while damage–or system failure in general–may also occur in ways that were not expected beforehand. This paper proposes a method that addresses these gaps. This is done by incorporating several additions to an existing vulnerability method that has been developed by the authors, using a Markov chain. With this method, there is no longer a need for modelling individual hits or failure scenarios. The additions are illustrated by two test cases. In the first one, a notional Ocean-going Patrol Vessel is considered, and damage is related to physical locations in the ship. The second test case considers a chilled water distribution system in more detail, with failures modelled independent from the physical architecture. The quantitative nature of the results provide an indication of the generic, overall vulnerability of the distributed systems, which is meant to be used in the early design stages for identifying trade-offs and prioritising capabilities.

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The Defence Materiel Organisation (DMO) of the Netherlands Ministry of Defence identified that detailing warship layouts to space level of detail during the concept definition design phase is a complex and time consuming process. Currently it can take up to 150 man hours to complete a feasible general arrangement plan (GAP). Yet, these GAPs are crucial for balancing requirements and budget with technical feasible designs. Insufficient consideration of spatial details during concept definition increases the probability that sizing and integration issues will emerge later in the design process. This paper discusses the first steps undertaken to integrate a new layout generation tool, called WARGEAR (WARship GEneral ARrangement), into the DMO ship design process. WARGEAR is able to semi-automatically generate feasible and balanced detailed layouts in a matter of minutes, thus providing almost real-time feedback and design insight to naval architects. In this paper the issues of tool validation and user acceptance are addressed via a realistic warship design test case and a presentation of the test case results to a larger group of naval architects and senior management at the DMO respectively. The test case showed that WARGEAR is able to generate detailed layouts that compare well to GAPs manually generated by naval architects. The attendees at the presentation were generally positive, but also provided valuable feedback for further development of the WARGEAR tool and methodology. This shows the potential of WARGEAR to increase the speed of detailed layout generation to a matter of minutes and to improve the early stage design process by providing early insight into detailed layouts and their design drivers. @en

During the concept definition design phase, significant effort is paid to the detailing of the internal layout of ships. At the Dutch Defence Materiel Organisation first a high level ‘functional arrangement’ is generated, which is further detailed into a ‘general arrangement plan’ (GAP), to validate the functional arrangement. The GAP generation takes considerable effort. Therefore, this paper proposes a novel method, called WARGEAR (WARship GEneral ARrangement), to support the designer with the generation of GAPs. The method aims to provide quick insight in the feasibility of the functional arrangement, i.e. check whether all spaces fit and can be connected via hallways and staircases according to international and naval rules. WARGEAR applies a new seed and growth algorithm as well as a ship’s network representation to semi-automatically generate detailed layouts based on predefined functional arrangements. A multi-deck and multi-compartment case study is presented as a proof of concept of the tool.

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This paper demonstrates the usefulness of an automatic topology generator that uses genetic algorithm techniques to generate many alternative system designs and in doing so enables design space exploration for on-board energy distribution systems. This will provide better insight in the relation between design requirements (e.g. budget), system design solutions and important perfor-mance characteristics like ship survivability in early design stages. The basic idea is to apply proven techniques as used for ship configuration (i.e. hull and layout design) to the design of “ship service systems”. The case study will consist of multiple, interconnected systems on board an Ocean-going Patrol Vessel that distribute electric power, chilled water and mechanical (propulsion) power.@en

This paper introduces a framework for analyzing distributed ship systems. The increase in interconnected and interdependent systems aboard modern naval vessels has significantly increased their complexity, making them more vulnerable to cascading failures and emergent behavior that arise only once the system is complete and in operation. There is a need for a systematic approach to describe and analyze distributed systems at the conceptual stage for naval vessels. Understanding the relationships between various aspects of these distributed systems is crucial for uninterrupted naval operations and vessel survivability. The framework introduced in this paper decomposes information about an individual system into three views: the physical, logical, and operational architectural representations. These representations describe the spatial and functional relationships of the system, together with their temporal behavior characteristics. This paper defines how these primary architectural representations are used to describe a system, the interrelations between the architectural blocks, and how those blocks fit together. A list of defined terms is presented, and a preliminary set of requirements for specific design tools to model these architectures is discussed. A practical application is introduced to illustrate how the framework can be used to describe the delivery of power to a high energy weapon.

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In order to investigate to which extent naval ships can execute their operational scenario after damage, an early stage assessment of the vulnerability of distributed systems needs to be carried out. Such assessments are currently mostly done by evaluating the performance of predefined concepts. However, such an approach does not necessarily lead to the most desirable solution, since solutions outside the scope of the designer’s preconceived ideas or experience are inherently hard to investigate. This paper therefore proposes several steps towards an approach that enables a vulnerability assessment that is independent of predefined concepts. This is done by incorporating several additions to an existing system vulnerability approach developed by the authors, using a Markov chain. With this approach there is no longer a need for modelling individual hits or damage scenarios. Whereas the approach has previously been shown in concept, this paper introduces three improvements that contribute to the applicability of the approach: 1)it is scaled up in order to model a larger number of compartments and distributed systems, 2) the hit probabilities for different compartments can be adjusted, and 3) it is shown how the availability of main ship functions can be derived from the availability of individual connections. A test case that compares two powering concepts (conventional and full electric powering) of a notional Oceangoing Patrol Vessel (OPV) is provided to illustrate the principles behind the improvements. From the results the two main contributions of this paper can be obtained: 1)the possibility to assess the system vulnerability for different levels of required residual capacity at different impact levels, and 2) and the quantitative nature of the results, aiding ship designers and naval staff with understanding the consequences of various concepts on the system vulnerability. @en

Warships rely on multiple distributed systems to function and perform their tasks. Vulnerability is a major driver in the design of these distributed systems. Aspects such as: the vessel and system component arrangement; the redundancy of system components; and the topology and routing of cables, ducts, piping and shafts to a large extent determine the ability of the ship to remain operational after incurring damage. The topology and routing of the connections within and between these distributed systems is often only addressed in later stages of the ship design, at which time changes to the general arrangement of the vessel and the distributed system components become difficult and costly. Earlier insight into the interrelations between the system’s vulnerability, the distributed system routings, and the vessel and system arrangements is thus deemed a critical step in designing robust distributed systems and ultimately more resilient warships. To address this, we propose a novel method for the early stage routing of ship distributed systems for vulnerability reduction. The approach uses network descriptions of the vessel layout and the distributed system topology to model both the routing and vulnerability problems. The paper outlines the modelling approach as well as the algorithms used. The usefulness of the approach as an early stage design tool is demonstrated by using it to design the routing for multiple (e.g. electrical, chilled water) distributed systems of a notional warship.@en

Preliminary ship design (or early stage design in US terminology) is the very first step in designing a new ship. In this stage ship designers attempt to find an affordable balance of the future owner's (customer or operator) ambitions and operational needs. This balance is then translated into more tangible design requirements. However, the search for such a balance and the accompanying design requirements is not a trivial task. Ships, and service vessels in particular, are considered as some of the largest, most complex, moving man-made structures which often need to operate for extended periods of time in a hostile environment. Not surprisingly, the preliminary design of such ships is also inherently complex. The search for a balanced design solution benefits from early insight into the complex interrelations and interactions between the design requirements, the accompanying solutions, and their performances and cost. Insight which is often gained by generating and studying numerous design alternatives with varying requirements, performances, and costs, in a broad and investigatory phase of preliminary design called concept exploration. However, the complexity of ships and the design problem also challenge concept exploration.@en