Low- and non-ice-class ship-ice interactions are modelled with a shared-energy approach, which typically models the internal mechanics with nonlinear finite element methods. For applications like the preliminary design phase and quick operational assessments of the ship’s structural capabilities, a finite element shared-energy approach can be time consuming and information intensive, therefore, an analytical share-energy algorithm is proposed. The proposed algorithm applies the upper bound energy methodology by equating the external collision energy, determined with the Popov collision model (Popov, et al., 1967), to the sum of the internal ice and structural response energies. The distribution of the internal energy, between the ice and the structure, is determined by iterating through possible shared contact forces until the sum of the internal response energies equals the external energy introduced into the system. The ice-crushing energy is modelled with Daley’s (1999) energy based ice collision force models, and the internal structural strain energy is modelled through a combination of classical beam theory and design of experiments methodology. The proposed model is benchmarked against a finite element ice wedge-ship grillage structure interaction.

The objective of this study is to develop the sensor-based structural health monitoring (SHM) system using a reduced order model (ROM) wherein a modal superposition method is implemented to reconstruct hull girder load distributions of the entire structure under wave-induced loads. Seakeeping and finite element (FE) analyses are performed to obtain the structural response for various wave conditions. A set of specific wave headings and frequencies is selected to construct base wave modes, and the structural response can be reconstructed under arbitrary wave loads. Case studies using a containership and an FPSO have been conducted to verify this new methodology.

Offshore wind energy is developing rapidly in the United States, particularly off the East coast, which has an extensive continental shelf and where the water depths are such that wind turbines founded directly on the seabed are the most attractive. Of the various foundation configurations that are feasible, it is the monopile that is expected to be most widely used. Another feature of the US East coast is that it is hurricane-prone region, which poses some unique challenges to designers. This paper summarizes research work undertaken to investigate how the role of modern optimization techniques can contribute to the design of such installation and does not establish any realistic project related implications. The project addresses the design of a 15 MW turbine, which represents the upper limit capacity of currently available wind turbines.

The importance of the blue economy is growing. A key element of this is the transition from fossil-based energy to greener alternatives such as offshore wind, marine renewables and other sources of energy. The ocean has been a source of food for millennia but newer, more innovative methods, of offshore cultivation are being developed and deployed. The engineering experience gained in offshore oil and gas industry is finding application in these examples of engineering for the blue economy. The trends are outlined together with the challenges faced by the engineering community.

This paper proposes a methodology for vessel-specific wave induced fatigue damage estimation and prediction based on Spectral-Based Fatigue Analysis (SFA) and Monte Carlo simulation (MCS). The impact of the vessel-specific wave conditions on the vessel’s fatigue damage is characterized by a relative value to the fatigue damage estimation using unrestricted service wave conditions. The relative fatigue damage can be used as an indicator to characterize the ship’s actual consumed fatigue life. For remaining fatigue life prediction, MCS is conducted with the consideration of both historical vessel-experienced waves and the wave conditions for unrestricted services. The mean and 95% confidence interval of future fatigue damage are predicted.

Offshore floating production platform truss type topsides structure often consists of truss, deck plates and stiffeners. Since these deck plates are usually thin, they are traditionally viewed as shear plates in topsides structure design, or ignored in the modeling to be conservative. While it seems to be conservative for hull structure evaluation to ignore the effects of deck plates completely, it is also possible to underestimate the loads transmitted to deck structure with an integrated deck and hull structure model. On the other hand, while taking into account the deck stiffened plates with normal stress and shear stress capacity, the hull structure design could benefit from less distributed loads on hull for an integrated deck and hull structure model, provided that the deck plate buckling capacity can be justified. In this study, a semisubmersible global FE model of hull and topsides deck is analyzed with three approaches: considering deck stiffened plates with full capacity, considering deck stiffeners and plates as shear plates, and ignoring deck stiffened plates. The differences in hull critical structure internal loads among these three approaches are quantified. For the integrated model, ignoring deck stiffened plate approach induces the least deck structure loads, and results in the highest hull structure loads especially in diagonal seas. The full capacity deck plate model induces the highest deck structure loads, and results in the lowest hull structure loads. The model in which the deck plate is modeled as a shear plate functions similarly to the model in which the deck plate is modeled as a regular plate for the internal load distribution. It is thus recommended that in all design stages, appropriate deck stiffened plates stiffness and its effects on the design should be taken into account.

To determine the risk involved in operations around offshore structures, static and dynamic traffic models can be used to assess the individual probabilities of incidents. This paper describes the underlying models to determine ramming (powered) as well as drifting collision frequencies for fixed objects at sea based on static traffic databases or AIS data. Static representations of the traffic allows for different risk models and accident statistics in determining the frequency of collision of a fixed object. AIS data, which shows the actual paths sailed by ships, can replace this static traffic database by a more dynamic risk model. As an example, this paper describes the approach for the risk assessment of an existing and future offshore installation.

The main purpose of this work is the development of the wave reconstruction and prediction system RIMARC for forecasting of waves and vessel motion in real time a few minutes in advance. RIMARC (Radar IMAge ReConstruction and wave prediction) utilises ocean surface measurements from a standard X-band navigation radar as input and provides the short-time forecast of phase-resolved temporal-spatial evolution of the wave field downstream as output. Independent field tests were performed on board the subsea offshore IMR vessel Normand Ocean. The tests covered significant wave heights from 1 to 7 metres and showed that the wave spectrum and short-time phase-resolved wave evolution at vessel site are correctly predicted 4-8 minutes ahead.

When a chain link is constrained from free rotation such as over a fairlead, the chain link is subjected to an out-of-plane bending (OPB) moment in addition to tension. Much research has been carried out to investigate the failure mode. This paper presents the nonlinear finite element analysis (FEA) studies on mooring chain OPB stiffness, OPB stress and moment. The effects of proof loading, pretension and friction coefficient on OPB stiffness are investigated. In addition, this paper provides the findings of the relationship between the interlink angle and total chain angle from linear FEA using the beam model. With the inputs from the numerical simulations, chain link tension-bending fatigue damage calculation procedures are summarized. Finally, OPB moment mitigation measurements are proposed to reduce the impact of OPB effect on chain fatigue life.

The recently developed Unified Offshore Standardization JIP – Specification for Offshore Pedestal-Mounted Cranes1 (Crane Specification) is a harmonized specification that is intended to be used by the maritime and offshore industries worldwide. This specification defines the minimum requirements for the design, fabrication, inspection, testing, installation and commissioning of offshore cranes. The potential users of this specification include vessel owners, operators, regulatory bodies, crane manufacturers, shipyards, as well as engineering companies. The potential benefits of this specification include improved safety, reduced costs and increased efficiencies due to the use of standardized requirements for offshore engineering, procurement and construction (EPC) projects. The development effort for this specification was undertaken by members of the Unified Offshore Equipment Joint Industry Project (UE-JIP) Working Group, including oil majors, operators, shipyards, research and development organizations, engineering companies, and classification societies. This paper examines the development of the Unified Offshore Standardization JIP – Specification for Offshore Pedestal-Mounted Cranes1, and provides further insight into how and why this specification was developed, what aspects are and are not addressed by this specification, as well as how this specification could be used for the benefit of the maritime and offshore industry. This paper also examines some of the latest developments in the offshore crane industry that are addressed by this specification, including subsea lifting and motion compensation systems.

In 1993, Richard D'Souza (Fellow), the principal author and his co-authors presented a landmark paper reviewing the Semisubmersible Floating Production System (FPS) technology at the SNAME centennial meeting in New York. (D'Souza et al., 1993a). The paper captured the twenty year progression of the FPS beginning with the Argyll field in the UK Sector of the North Sea in 80 meters of water that was converted from a semisubmersible Mobile Offshore Drilling Unit (MODU) and began producing in 1975. During this period about twenty five FPSs were installed, primarily in the North Sea and Brazil. Most were converted from semisubmersible MODUs. The deepest was in 625 m, the largest displacing 45,000 mt and the maximum oil rate was 70,000 bopd. Over forty FPSs have been installed since then, most of which are purpose built platforms. The technology has expanded to a maximum water depth of 2400 m, displacements exceeding 150,000 mt and production rates of 300,000 boepd. The inherent versatility and flexibility of the FPS to adapt to a wide range of water depths, payloads, metocean conditions and future expansion, has resulted in the FPS superseding the Tension Leg Platform (TLP) and the Spar platform as the most widely used floating production platform after the Floating Production Storage and Offloading (FPSO) platform. Its field development applications range from marginal reservoirs to giant deepwater oil and gas fields across the globe. This paper, authored by Richard D'Souza with a new team of co-authors, is a sequel to the 1993 paper and is intended as a historical and technical archive of the evolution of the FPS technology in the ensuing twenty five years. It highlights the importance of the Naval Architect and Ocean Engineer whose role has evolved from a peripheral to a major player in the design, fabrication and installation of the FPS. This paper has two objectives. One is to inform Operators and Contractors engaged in developing deepwater fields by providing a historical overview of lessons learned and technology evolution of the FPS. The other is to inspire graduate and post graduate Naval Architects and Ocean Engineers to consider a career in the offshore industry where they will have an impactful role in shaping the future of deepwater floating production platforms.

In this paper, a method is presented for visualizing and understanding the operational dynamics of a shipping operation. The method uses system performance measurement and functional signatures. System performance measurement allows assessors to understand the level of performance that is being achieved by the operation. The functional signatures then provides insight into the functional dynamics that occur for each level of performance. By combining system performance measurement with functional signatures, there is a framework to help understand what levels of performance are being achieved and why certain levels of performance are being achieved. The insight gained from this approach can be helpful in managing shipping operations. Data from an ice management ship simulator is used to demonstrate this method and compare different operational approaches.

Ships interact with the environment in several ways. The focus in this paper is on how ships interact with the wind and how this is treated in design. It is generally sufficient in most cases to model wind force as a static load. However, there may be circumstances where a more detailed description of the wind is appropriate. Some examples discussed include stability under transverse winds, aircraft flight deck operations and wind resistance. The paper summarizes key properties of the wind and recent research related to some key windship interactions. This includes discussion of the challenges and possible remedies.

We investigate the feasibility of using Magneto-Hydrodynamics (MHD) to implement a propeller-less propulsion system. The basic principle behind MHD is to use the (Lorentz) force produced by the interaction of electric and magnetic fields to generate thrust on a conducting fluid in motion. Electrodes are lined up along the walls of the duct which act as the source of the electric field. Sea-water acts as the conducting medium for the current when it passes through the duct. This medium is then subjected to a strong magnetic field within the duct, thereby producing an axial force, i.e. an axial thrust. Propulsion systems based on MHD require virtually no mechanical components; therefore, a good application would be to design a propulsor which produces very little noise for small underwater vehicles. Results of a preliminary feasibility study on this application are presented in this paper. An approximate, consistent model to estimate the propulsion performance of a MHD propulsor for small underwater vehicles is introduced and analyzed. The model is generalized from the hydrodynamic point of view to consider inlet and outlet convergent/divergent nozzles. The general model is applied systematically varying the main design parameters considering a small autonomous underwater vehicle (AUV). Results show that non trivial trade-off conditions exist between inlet and outlet geometry, number of MHD channels, applied magnetic field and voltage, as the vehicle speed changes, to get the highest propulsion efficiency.

Comparing with other forms of oil production platform, FPSO shows various characteristics such as high input, high risk and high profit. Therefore, risk and reliability evaluation research of FPSO is of great significance. This paper provides an outline of risk based management for FPSO among the total life circle. On the basic of accident causation analysis, risk assessment and risk restraining method of explosion and fire nonlinear response analysis are given. In addition, two examples about explosion response and fire response simulated by FLACS CFD and ANSYS/LS-DYNA is conducted in this paper. Beyond that, given asset integrity management (AIM) systems for FPSO. Based on the above work, profound understanding about risk management of FPSO can be clearly developed, and provide valuable recommendations for FPSO designs.

The modularized design and construction philosophy is a common practice for large onshore and offshore projects due to its opportunity for schedule and cost-savings. Multiple modules are fabricated at different construction yards across the world and then transported to service sites by marine transportation vessels. During transportation, the seafastening system is required to secure modules on transportation vessels. The seafastening system is designed to support the forces imposed on the module by accelerations, motions and deflections of the vessel, and distribute the concentrated forces from the module onto the vessel. The system reliability will depend highly on the forces for which the seafastening is designed. The determination of the forces is typically based on decoupled analysis where the module and vessel are analyzed separately. The resulting forces are usually over-conservative. However, this paper presents a more advanced and accurate approach where interaction FE analysis is utilized to calculate the reaction forces. A light weight seafastening system is designed based on the calculated reaction forces. The system consists of a series of grillage beams with stoppers and wing plates welded to the vessel deck. Additional clips are used to restrain the module uplift. The proposed design allows for an easy and efficient seafastening removal, an optimum use of the vessel capacity and a reduction in fabrication costs. Results from a sample seafastening design are presented.

For the numerical simulation of behavior of floating multi-bodies, the Computational Fluid Dynamics(CFD) is generally preferred due to its benefits in describing nonlinear hydrodynamic effects. The realistic modeling of two floating bodies should include hawsers and fenders which are essential for side-by-side mooring configuration during operations. In this study, each of the numerical libraries of hawsers and fenders is developed for open source CFD software, Open FOAM. Numerical analysis of two floating vessels in a side-by-side configuration is performed considering hawsers and fenders using developed modeling libraries. The wave conditions are regular waves in beam sea direction. In conclusion, the numerical libraries of hawsers and fenders are successfully implemented in the Open FOAM.

After approximately 9 years in service out of their 30 year design life, excessive corrosion on FPSO mooring chains in West Africa was observed through detailed chain inspection and measurements. The offloading operation of the FPSO was adjusted proactively in response to the increasing risk of potential mooring failure. An extensive engineering study determined that the heavily corroded water column chain sections for each of the FPSO's anchor legs needed to be replaced by new chains of the same size but higher grade. Also, a detailed engineering study was conducted to determine the best replacement strategy for each anchor leg. During the mooring line replacement campaign, it was confirmed that the buried sections of chain did not experience significant corrosion and therefore were acceptable to remain in the FPSO's mooring system for the long term. With a well—planned installation procedure in place, replacement of all heavily corroded chains was successfully completed in 50% of the estimated time, without interrupting production and offloading operations, and more importantly without injury or incident. All class and Flag State restrictions have been lifted immediately and the FPSO's operation is restored to its original design condition. Upon recovery of the original chains, lab tests were conducted to investigate the residual strength of the corroded chains. The test results can serve as valuable input data for life continuation or life extension of an FPSO in the future.

To increase efficiency in terms of productivity of offshore projects, a module is assembled and installed as large as possible. For the demanding from the project, the Hyundai Heavy Industries (HHI) has built a heavy lift crane vessel and made a total operation management system for the effective and safe operation. In this paper, the total operation management system of heavy lift crane vessel, which includes 72 hours weather forecast system and workability assessment, is introduced. The weather prediction system is co-developed by KIOST & HHI for the near shore of the HHI's ship and offshore yard. And the operation criteria estimation has been performed using time domain simulation. For the accurate simulation, the wind tunnel test of the heavy lift crane vessel has been carried out. Field workers can get the 72 hours weather information including current, wave and wind from the HHI weather forecast system and then make a decision for the operation using the workability assessment.

The introduction of the Energy Efficiency Design Index (EEDI), which is applicable for various types of new-built ships after January 1, 2013 raised concerns regarding the sufficiency of propulsion power and steering devices to maintain maneuverability in adverse conditions. This was the motivation for the initiation of the EU research project SHOPERA (Energy Efficient Safe Ship Operation, 2013–2016, http://www.shopera.org ). The aim of this project is the development of suitable methods, tools and guidelines to effectively address the above concerns and to enable safe and green shipping. Within the framework of SHOPERA, a comprehensive experimental program of more than 1,300 different model tests for three ship hulls of different geometry and hydrodynamic characteristics has been conducted by four leading European maritime experimental research institutes: MARINTEK-Norway, CEHIPAR-Spain, Tech. Univ. Berlin-Germany and Flanders Hydraulics Research Belgium. The tested hull types refer to two public domain designs, namely the KVLCC2 tanker and the DTC container ship, as well as to a small RoPax ferry design, which is a proprietary hull design of a member of the SHOPERA consortium. The conducted tests were distributed among the four research institutes to benefit from the unique possibilities of each facility and to gain added value by establishing data sets for the same hull model and test type at different under keel clearances (UKC). This paper presents the scope of the SHOPERA model test program for the two public domain hull models – the KVLCC2 and the DTC. The main particulars and loading conditions for the two vessels, as well as the experimental setup, is provided to support the interpretation of the experimental data that is presented. The focus lies on the added resistance and drift forces at zero and moderate forward speed, propulsion and rudder force tests in waves and the assessment of manoeuvrability of ships in waves, as compared to calm water conditions.