The requirement for fossil fuels expedites for an advancement in the existing subsea technology. The developments evolved as the search for hydrocarbons moved from onshore to offshore, followed by a transition from shallow to deep and ultra-deep waters. Another huge milestone was achieved, when production systems made a transition from topsides to subsea units for efficiency. Currently, there is an enormous drive to minimize the operational costs involved in the processing of hydro-carbons. Researches are underway towards what would be yet another significant feat in the oil and gas industry, which is by moving the processing systems to subsea. One such impressive concept, which is being developed, is the Submerged Production Unit (SPU). This study is an initial attempt to investigate the challenges associated with the SPU focusing on the factors influencing design, launching and towing. A design concept that goes back and forth from performance and design spaces was used in modelling the SPU, solving the complexity that revolved around assembling the hollow Glass Reinforced Plastic (GRP) beams with subsea buoyancy materials. Submerged Tow Method (STM), an adaptation of Controlled Depth Tow Method (CDTM) was used instead of the conventional way of lifting the equipment using cranes of heavy lift vessels or construction vessels on site during deployment considering cost and safety. OrcaFlex software was used for towing analysis. End force in global X direction on towline, obtained from static analysis was used to identify the Bollard Pull (BP) required for towing the SPU. Dynamic analysis was performed for different environmental conditions to identify the maximum effective tension on the towline. BP requirement of 100t was estimated from the towing analysis. This study was carried out by author as a master’s thesis [1].

Nowadays different types of unmanned underwater vehicles (UUVs), such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), are widely used for sub-sea inspection, maintenance, and repair (IMR) operations in the oil and gas industry, archaeology, oceanography and marine biology. Also, lately, the development of underwater snake robots (USRs) shows promising results towards extending the capabilities of conventional UUVs. The slender and multi-articulated body of USRs allows for operation in tight spaces where other traditional UUVs are incapable of operating. However, the mathematical model of USRs is more challenging compared to models of ROVs and AUVs, because of its multi-articulated body. It is important to develop accurate models for control design and analysis, to ensure the desired behaviour and to precisely investigate the locomotion efficiency. Modelling the hydrodynamics poses the major challenge since it includes complex and non-linear hydrodynamic effects. The existing analytical models for USRs consider theoretical values for the fluid coefficients and thus they only provide a rough prediction of the effects of hydrodynamics on swimming robots. In order to obtain an accurate prediction of the hydrodynamic forces acting on the links of the USRs, it is necessary to obtain the fluid coefficients experimentally. This paper determines the drag and added mass co-efficients of a general planar model of USRs. In particular, this paper presents methods for identifying fluid parameters based on both computational fluid dynamic (CFD) simulations and several experimental approaches. Additionally, in this paper, we investigate variations of the drag force modelling, providing more accurate representations of the hydrodynamic drag forces. The obtained fluid coefficients are compared to the existing estimates of fluid coefficients for a general model of USRs.

Many approaches exist to build environmental contours, i.e. the ensemble of joint metocean parameters corresponding to a N-year return level. However, these contours may provide rather different curves according to their calculation process. In this work, the use of response meta-models is introduced for the inter-comparison of environmental contours for two application cases: the roll of a FPSO and the tension in a mooring line of a semi-submersible. Some state-of-the-art methods available for modelling multivariate extremes are applied for two or more variables and in a directional context. Among the conditional models, joint parametric laws (such as Weibull, log-normal...), Heffernan and Tawn simulations and several copula are investigated. Two ways of contour building are considered in 2D and 3D: Inverse First Order Reliability Model (I-FORM) and physical-space Huseby contouring method. The comparison between the resulting design points are presented for both applications. The combined wind, wave and current parameters statistics (including directions) are presented, in addition to the extreme loads obtained from the meta-models. The advantages and drawbacks of each method are reviewed. Some key findings are finally presented, pointing out the interest of a meta-model to determine the more realistic set of design points in function of the structure response of interest.

Due to the dynamic development of the oil and gas fields in the Arctic, the challenges of supply fleet sizing and composition in this region are becoming relevant. In most studies, the Arctic is mainly associated with ice conditions, but it is not the only factor that influences the design of platform supply vessels (PSV) and corresponding marine transport systems (MTS) for this region. The structure of cargo flow (i.e. its distribution by cargo types) affects the supply system significantly. It defines the level of utilization of vessel capacity that determines transport efficiency. At the same time, the literature represents this aspect poorly. This paper describes an approach to optimize supply fleet configuration by the criterion of total cost considering both non-stationary ice conditions and structure of cargo flows. The cargo-flow-oriented design concept incorporates the detailed calculation model of PSV and the special tactical planning algorithm. PSV model allows considering the influence of cargo spaces on the main characteristics and operational parameters of the ship. It covers the main design aspects of PSVs: general arrangement; lines plan; resistance in open water and ice; engine and propeller characteristics; hydrostatics; capacity and mass calculation. The pseudo-optimal tactical planning algorithm is intended to build the plan of voyages and to set the size of fleet considering the structure of cargo flow. As the test example, we examine a task of servicing the group of platforms in the Kara Sea. The case study shows that cargo flow structure has a high influence on the efficiency of PSVs in case of high-load operation; while a widespread “deck-cargo” approach is unable to consider this aspect because it ignores the vessel’s carrying capacity and payload. The conclusion about a higher efficiency of PSV compared to AHTS with the same displacement was drawn.

Recently, the demanding for effective utilization of marine spaces in forms of oceanic architectures has been rising high by new social requirements as well as other constructions, and the like. Consequently, architecutural characteristics and structural effectiveness of them should be reevaluated accordingly. Objects of this study are four architectures located in the shallow area of sea around Kyushu Region,namely Marizon, Genkai Sea Hot Spring Palea, Marine Aquarium Sea Doughnut, and Akasaki Elementary School. Their functions, structures, setting forms, then conditions for situating buidings, processes of construction at sea, and challenges after construction had been clarified by our literature survey, the hearing investigation and the field research. Our results are as following. Functionally, each above architectures has respective facilities to fully utlize regional marine resources and environment, etc.; Structurally, all of them had premeditated both the bad conditions of coastal environment and providing spaces for water activities. In terms of their construction processes at sea, factors blow had been carefully considered before being sited: limitations of local spatial scale, full utilization of local environmental conditions, measures against disadvantages of sites, the particularities of regional nature, environment, and society. In conclusion, our findings suggest that planning of the oceanic architecuture should combine the usage, the fuction, and the understructures well with its marine conditions.

In recent years, great regard has been given to the participation of various administrative organizations, NPOs and local residents in coastal zone management. Following the formulation of the “Canal Renaissance Project (Tokyo Metropolitan Gov. Bureau of Port and Harbor, 2005)” as a step towards easing restrictions to vitalize canal spaces in the Tokyo waterfront area, local organizations are developing commercial and recreational uses of canal spaces. In this report, we have conducted field research and hearings with managers and business people in five regions of the Tokyo waterfront where the Canal Renaissance Project is being implemented. Through this research, we have observed the usage conditions of the canal spaces and how multiple organizations cooperate with each other, and attempt to identify problems associated with the use of canal spaces by local organizations. The results show that eased regulations on water area usage permissions have created new opportunities for local businesses, store associations and NPOs to utilize canals. By establishing floating restaurants and floating piers, waterfront areas have been developed with consideration for the spatial structure and surrounding area of canals in each region. We have observed a large variety of interactions between organizations and groups, and the establishment of a system centered on a committee made up of local businesses and residents in each region. However, we have also noted that due to the strong individuality of the projects carried out in each region, they have not lead to any inter-regional cooperation, thus not necessarily successfully utilizing the inherent spatial continuity of the canals. There have also been examples of complication of the committees that connect the local residents involved in the projects and the government. This is an issue in the management and operation of canal usage. From the aforementioned results, it is clear that the projects observed in canal usage under the eased regulations are organized such that they are directly carried out by committees, in a so-called “committee-based model.” There is no “local coordinator” present to handle the tasks of reconciling opinions between project leaders, applying for water area usage permission, maintenance of facilities, acceptance of new participants, and the like.

The arrangement design of ships and offshore plants is normally being made based on data of the past design and experts’ experiences. When performing the arrangement design, experts refer the past data and add additional requirements to the data for a new design based on their experiences. During this task, delay in design can occur due to the data missing or the absence of experts. In addition, most of ships and offshore plants are operated in the ocean environment so that spaces that can be filled with components for them are restricted. In this sense, there is a need to accumulate data regarding the past design, experts’ experiences, and design rules as a systematic structure. And a demand for optimization technique for the arrangement deign of ships and offshore plants are increasing. For this, an arrangement design framework for ships and offshore plants based on expert system and optimization technique is proposed in this study. And the proposed framework is applied to a problem with regard to the arrangement design of a small size submarine, and an FPSO topside. The results shows that the proposed framework can be used as a new tool for the arrangement design of ships and offshore plants.

This paper describes the design process of a high speed mono hull RoPax ferry which operates at a Froude number of 0.4. The design task was quite challenging, as two possible transport concepts were in principle possible: Two ships were needed with a total speed of 50knots, which could result in a combination of a 30kn high speed Catamaran plus a conventional 20kn RoPax Ferry or alternatively in two identical sister vessels of 25kn each. The solution with the high speed catamaran plus the conventional RoPax-Ferry defined the total cost budget, which must not be exceeded by the design of the two sister vessels. This resulted in a tough boundary condition and made life cycle cost evaluations necessary. Due to harbor restrictions, the length of the ships was limited by abt. 110m, resulting in a Froude number of abt. 0.4. This resulted in high costs for the propulsion system. The ferries should initially have open RoRo-Cargo spaces for cost reasons, which made the stability requirements (weather criterion plus Stockholm Agreement) quite challenging. This also strongly influenced the design of the final hull form. As the ship is very sensitive to weight, detailed steel structure optimizations had to be carried out to optimize the main grillage systems of the vehicle decks. The hull form and the appendage design required careful optimization to guarantee the required service speed with the engine power which was available in the price budget. As no vessel of comparison was available, the speed power estimation as well as all design tasks had fully to rely on numerical predictions. As the ship had further demanding requirements for course keeping and comfort in waves, the optimization of the hull form must include also these issues. The paper shows that the design of complex ships is actually a holistic task which includes many engineering disciplines. The paper also shows that 1 st principle based design methods can support the design process of specialized vessels significantly.

The objective of the paper is to present the structural design support system (DeSS) rationale for the reliability based design optimization (RBDO) in the concept design phase. Basic steps are as follows: • Interactive identification of the design problem (design variables, constraints, objectives) as well as design problem variates and their distribution parameters. Safety related design criteria are used as objectives and as constraints in the presented procedure; • Calculation of the cross section ultimate longitudinal strength criteria based on the extended Smith’s method; based on the Report SSC-398; • Selection of non-dominated designs (Pareto-optimal, NDD points) for the given deterministic design criteria; • Calculation of reliability/deterministic safety measures. Novel FASTREL code, based on the Dimension Reduction Method (DRM) is used for the reliability calculations; • Generation of insight into the Multi Attribute Decision Making (MADM) process with 5D graphic presentation of designs in design and attribute spaces in the interactive OCTOPUS Designer (Demak/DeView) IT modules. Practical application of the developed concept design methodology and of the design environment to the structural design of the verifiable test example corresponding to SSC-398 report. DeSS was used in fast generation of optimal designs using MODM (MOSLP) and MADM (MOPSO) techniques. To speed up the RBDO design process deterministic and probabilistic formulations of design problem were run concurrently and supporting each other are presented using the safety related design attributes (deterministic and reliability based) for the NDD supported decision-making technique.

A global-local analysis methodology based on fluid-structure coupling is used to investigate the mechanical responses of both composite and steel risers. Since the design of the riser system can be a daunting task, involving hundreds of load cases for global analysis, semi-empirical fluid load models are considered for the reduced order computations of full-scale riser models. The structural performance of composite risers under real sea current conditions is investigated systematically and discussed with regard to the practical concerns in full-scale settings. The failure envelops of internal liners are found to be within that of the composite layers, which reveals that the liner is the weakest link for composite riser design. Results show that the composite risers can be more prone to vortex-induced-vibration (VIV) due to their lower structural frequencies. In the present study, the composite riser yields 25.5% higher RMS strains than the steel riser. Placement of buoyancy modules along the riser may be critical for the design against VIV, and our results show that the modules are not recommended at the top region of the riser, especially if a top-sheared current is expected. Instead, it is preferable to implement them at the bottom-half portion of the riser and as a continuously buoyed region rather than short discrete buoys separated with gap spaces.

A new approach to estimating environmental contours has recently been proposed, where the contours are estimated in the original physical space by Monte Carlo simulations from the joint distribution directly rather than applying the Rosenblatt transformation. In this paper, the new and the traditional approach to estimating the contours are presented and the assumptions on which they are based are discussed. The different results given by these two methods are then compared in a number of case studies. Simultaneous probability density functions are fitted to the joint distribution of significant wave height and wave period for selected ocean locations and, for each area, environmental contours are estimated for both methods. The chosen locations are characterised by different wave climates. Thus, the practical consequences of the choice of approach are assessed. Particular attention is given to mixed sea systems, i.e. a combination of wind sea and swell. In these situations, the new approach for environmental contours may fail to identify realistic conditions along some parts of the contours while for other wave conditions the contours are quite similar. The paper also briefly discusses possible ways of amending the new approach to estimating the contours to obtain more realistic conditions all along the contour lines.

Novel design methodology with inclusion of reliability and robustness-based design criteria is presented. Robustness is defined as the insensitivity of a design attribute to uncontrollable design parameters. The developed design procedure for the concept design phase is divided into two basic, coordinated tasks: (1) multi-criteria topology/geometry optimization of the ship structural model; (2) scantlings / material multi-criteria optimization of structural panels. Reliability criteria and robustness of design attributes are applied as relative measures of quality, besides standard design attributes such as costs and weight. They are used in generation of Pareto-optimal design variants. Reliability attributes used for the panel design are compared with respect to fidelity and computational efficiency. A novel method for fast reliability calculations is presented using dimension reduction method (DRM) as implemented into FASTREL software. The method is verified with respect to accuracy and speed on the box girder design and panel design with CalREL methods (MC, FORM). The design procedure steps are executed in the predefined sequence of design sub-problems, using the fast and balanced collection of analysis and synthesis modules/methods of the MAESTRO/OCTOPUS design system. They are as follows: • Probabilistic determination of design loads; • Calculation of the structural serviceability and ultimate strength criteria on the panel (macro-element) level; • Calculation of the cross section ultimate longitudinal strength criterion; • Calculation of reliability and robustness measures on the panel level (safety) and on the global level. Other design attributes (initial cost, structural weight, etc.) are also determined; • Generation of the Pareto frontier for the selected test structure based upon the cost–safety design paradigm; • Generation of insight into the multilevel optimization process with graphic presentation of designs in design and attribute spaces. Practical application of the developed concept design methodology and of the design environment to the structural design of modern multi-deck ship elements (panels) is presented for verification/validation of accuracy and speed of FASTREL module.

Some foundations of Ocean engineering structures are always in addition to withstand the vertical gravity loads, but also to horizontal loads induced by sea wave and current, which makes the foundation subjected to concentrated force, overturning loads and torque loads, the above loading state including vertical, horizontal and overturning moment loads are termed combined loading. So it is very necessary for the safety of ocean engineering structures to study the deformation law of submarine seabed due to combined loading. On the basis of the three-dimensional elastic mechanics solution of circular foundations, the deformation law of submarine clay under circular foundation with six degrees of freedom is analyzed in detail using numerical calculation methods. Based on the above numerical results, this paper gives the elastic deformation law of clay in three dimensional spaces, gives a modification to the traditional elasticity theoretical solutions, and gives clay coupled deformation mechanism under three-dimensional circular foundation with six degrees of freedom.

This work presents a computer program developed for the definition of Deck Accommodation Arrangements of ships and craft that allocates spaces in an automated process, in order to help the designer with options and initial ideas for its definition or to optimize arrangements propositions. This optimization process is usually done based on experience, using maritime regulations and practices. It is an evolution of previous works [14] which adopted the Quadratic Assignment Problem (QAP), that allowed the user to select units to be assigned to demarcated spaces and the program provides optimized options of arrangements, which can be transformed, in turn, into drawings. In this work, a hybrid meta-heuristic has been incorporated to the program, namely the Greedy Randomized Adaptive Search Procedures — GRASP [7], and for the local search of solutions, the Variable Neighborhood Search — VNS [8], to improve the results. The program incorporates the mathematical model, containing menus of types of accommodation/compartments or deck units, for the user’s selection. Visualization and manipulation screens for friendly use were created, that allow the designer to quickly assemble deck arrangements in spaces, with an indirect tri-dimensionality feature. The program processes position and flow matrices, being the later ones determined through calibration (being modifiable) as a function of applicable Regulations of ILO 147 Convention, SOLAS and NORMAM (Brazilian Administration), incorporating as well maritime practice and usual ergonomic criteria for requirements of safety and habitability. The results can be used for General Arrangement drawings and can aid in the calculations of light weight and center of gravity, sail area, etc. A small discussion of recommendations for accommodation arrangements of the related regulations, rules of thumb derived from design practice and ergonomic criteria is provided.

Since its first use in offshore project for drilling and production platform in 1984, more than two dozens of Tension Leg Platform (TLP) structures have been installed in oil and gas fields. The trend for using TLP structure in the exploration of deepwater oil fields has also gained momentum in recent years. The major driving force behind this is because the TLP structure has relatively smaller heave motion, thus it can be used for dry tree application in deepwater. Knee brace has found applications in the design of TLP structures. These vertically diagonal structure members are mainly used to support heavy vertical loads when the column spaces are large. The applications of knee braces have been used for two different stages: the integration stage and the in-place stage. For large topsides, the integration of the platform is usually performed in two or more separate lifting. The knee brace is used to temporarily support the pieces of the topsides before they are integrated together. For conventional type of TLP structures, the top tensioned vertical risers (TTRs) are placed in the middle of the platform to stay away from the mooring system and other subsea systems. The large column-to-column space and heavy TTR loads create some technical and economic challenges for the design of deck structures. To effectively take these vertical loads, knee brace is used to cut down the span of the deck supports. The challenge for this application is how to effectively share the vertical loads while at the same time not to induce much global dynamic action on the knee brace structure. This paper will review the application of knee braces in TLP projects, study the impact of the knee braces to the global action of the hull and topsides structures, and discuss the results of the analysis through a project example. The study will concentrate on the global load distribution through the knee braces, and the interaction between the knee braces and the hull structure under the global load action. Analysis results will be presented and the impact of the knee braces to the global structure will be discussed. These results will show that with proper configuration layout, the knee brace can be designed mainly to take the vertical static load, thus minimize the participation of the dynamic effect. The Author will also discuss the pros and cons of the knee brace structure in TLP application and some key issues which deserve attention during the application.

Passenger Ro-Ro ferries have proved to be extremely vulnerable regarding their hydrostatic stability when damaged. This is not only due to the design of their car decks. After an abrupt ingress of water caused by a maritime accident, the spaces below the car deck can experience dangerous intermediate flooding stages that might lead the ship to sink. The intermediate flooding stages depend upon hosts of factors that are interdependent. Some of them eventually interact during the flooding. An experimental campaign using the midsection of the PRR02 - ITTC/SiW passenger Ro-Ro ferry was devoted to provide a thorough insight to the flooding physics and to quantify these interactions using a novel-to-ocean-engineering methodology, the so-called DOE method. The physical background and the experimental set up of this campaign are presented in the previous one (OMAE2010-20047). This paper is devoted to presenting the experimental methodology and the first findings. The flooding is found a complex phenomenon in which a strong interaction between water and air occurs, also in coupling with the hydrodynamic efforts. Model tests based on one-factor-at-a-time experiments highlights the importance of the damage area and the time of damage creation in the ship behavior during the transient phase. We advocate the use of the DOE methodology to deal with stability problems and to find a model quantifying the intermediate flooding stages.

Passenger Ro-Ro ferries have proved to be extremely vulnerable regarding their hydrostatic stability when damaged. This is not only due to the design of their car decks. After an abrupt ingress of water caused by a maritime accident, the spaces below the car deck can experience intermediate flooding stages that might be more severe than the final condition, and the ship could actually sink in these early stages. The intermediate flooding stages depend upon hosts of factors pertaining to the vessel itself, the accident that caused the damage, as well as the environment. These factors are interdependent, and some of them interact during the flooding. An experimental campaign using the midsection of the PRR02 - ITTC/SiW passenger Ro-Ro ferry was devoted to provide a thorough insight to the flooding physics by quantifying these interactions using a novel-to-ocean-engineering methodology, the so-called DOE method, and try to find and then optimize a model for the transient flooding phase of Passenger Ro-Ro ferries. The present paper presents the physical background of the problem, as well as the innovative experimental set up that have been conceived to attain the objectives and hopefully lead to sound conclusions.

The Central Disaster Management Council of the Japanese Cabinet Office estimates that a class-M7 earthquake will occur in Metropolitan Tokyo or the Tokai area within the next 30 years. In 1995, Japan suffered devastating damage from the Great Hanshin-Awaji Earthquake and has since been devoted to disaster management. Since there has been no report anywhere in the world on a sea-based relief system, our research will lead to a review of ocean spaces in terms of their value in waterfront metropolitan cities. In this research, we have explored the feasibility of a relief system utilizing Entertainment and Party Boat (EPB) which can cover areas from the sea to rivers, and we investigated navigable routes of rivers to suggest effective utilization of ocean spaces and river areas in the event of disaster. As a result, we determined the rescue potential drawing upon EPB. A river survey was also conducted to classify navigable routes by boat size.

Coastal spaces (including land areas and sea areas) in Japan are managed by the state or local governments, and their private use by individuals was not allowed unless contribution to public interest was ensured. Since the Designated Manager System for public facilities was established in 2003, management of an increasing number of public facilities based on the Local Autonomy Laws has been consigned to private sectors (called “designated managers”) nominated through the decisions of the local councils, rather than to public bodies based on the conventional “Management Commission System.” Regarding marinas including land areas and sea areas, we conducted a comparative analysis of their convenience, comfort, serviceability, and so forth before and after introduction of the Designated Manager System from the viewpoint of marina users to discuss how the private sector should manage coastal regions.

LargE Admissibility Perturbations (LEAP) is a general methodology, which solves redesign problems of complex structures with, among others, forced response amplitude constraints. In previous work, two LEAP algorithms, namely the Incremental Method (IM) and the Direct Method (DM), were developed. A powerful feature of LEAP is the general perturbation equations derived in terms of normal modes, the selection of which is a determinant factor for a successful redesign. The normal modes of a structure may be categorized as stretching, bending, torsional, and mixed modes and grouped into cognate spaces. In the context of redesign by LEAP, the physical interpretation of a mode-to-response cognate space lies in the fact that a mode from one space barely affects change in a mode from another space. Perturbation equations require computation of many perturbation terms corresponding to individual modes. Identifying modes with negligible contribution to the change in forced response amplitude eliminates a priori computation of numerous perturbation terms. Two methods of determining mode-to-response cognate space, one for IM and one for DM, are presented and compared. Trade-off between computational time and accuracy is assessed in order to provide practical guidelines to the designer. The developed LEAP redesign algorithms are applied to the redesign of a simple cantilever beam and a complex offshore tower.