Nowadays, there is an increasing demand for use of jack-up crane vessels to install offshore wind turbines. These vessels usually have shallow soil penetration during offshore crane operations because of the requirement of frequent repositioning. The soil-structure interaction should thus be properly modeled for evaluating the motion responses, especially at crane tip at large lifting height. Excessive crane tip motion affects the dynamic responses of the lifted components and subsequently affects the safety and efficiency of operations. The present study addresses the effects of soil behaviour modeling of a typical jack-up crane vessel on the dynamic motion responses of a wind turbine blade during installation using a fully coupled method. The coupled method account for wind loads on the blade and the vessel hull, wave loads on the vessel legs, soil-structure interaction, structural flexibility of the vessel legs and crane, and the mechanical wire couplings. Three models for the soil-leg interactions and two soil types are considered. The foundation modeling is found to have vital effects on the system dynamic motion responses. The characteristics of system motion differ under different types of soil. Compared to the combined linear spring and damper model, the simplified pinned and fixed foundations respectively lead to significant overestimation and underestimation of the motion responses of the blade during installation by jack-up crane vessels. To ensure safe and efficient offshore operations, detailed site specific soil properties should be used in numerical studies of offshore crane operations using jack-up crane vessels.

In this paper, the operability of an Offshore Service Vessel (OSV) is looked into for different heading orientations of the vessel. Traditionally, the OSV heading orientation has been into the predominant current direction to prevent large beam current forces and thruster utility. However, such an orientation can lead to unfavourable wave headings which can cause large first order motions making it difficult to operate the gangway on board the vessel. Hydrodynamic time domain simulations were run for 1-year of hindcast weather data from an operational wind farm site in the Netherlands for different OSV heading orientations. The results of the simulations can be used to optimize the OSV heading strategy and increase uptime, reduce waiting time and energy loss associated to this waiting time.

The typical offshore wind turbine generator (WTG) currently being installed worldwide produces 6 to 8 megawatts of electrical power and stands more than 100 meters above the ocean surface. The next generation turbines will produce 12 megawatts or more. In the summer of 2016 five of these turbines were installed in the coastal waters of Rhode Island. They are representative of the latest in a constantly evolving series of WTGs. As manufacturers continue to develop more powerful turbines, larger and larger specialized vessels will be needed to lift the components at assembly sites offshore. The process these vessels use to build America’s offshore windfarms will need to be different from the approach normally used at sites outside the U.S. This is due in part to regulatory restrictions imposed by the Merchant Marine Act of 1920, which is more commonly known as the Jones Act. As it pertains to offshore windfarm construction, the Jones Act prohibits foreign-flagged vessels, (vessels built outside the United States) from moving cargo between two U.S. ports. Under the law, an offshore windfarm within territorial waters is considered a U.S. port. Therefore, employing a foreign built windfarm construction vessel to transport components from a nearby port to the construction site, as it typically does, violates the Jones Act. Although the Jones Act might appear to be a deterrent to the development of offshore wind in the U.S., it is not. The developers of the Rhode Island’s Block Island Wind Farm (BIWF) used a combination of U.S. and foreign-flagged vessels to construct BIWF, while remaining in compliance with the law. This paper reviews the approach used at Block Island and discusses how it can be applied to future projects. An analysis of alternatives for various vessel fleet combinations that can be used for this purpose is provided. The analysis is based on results produced by a throughput and scheduling model developed by the authors. The model leverages the experience gained during the construction of BIWF, and was validated with data collected during the project. The alternatives include scenarios utilizing existing vessels modified for windfarm construction service, foreign-flagged windfarm construction vessels, and new vessels specifically built for the U.S. market. The paper concludes with a review of the relative efficiencies of various fleet configurations while undertaking the construction of a notional windfarm located off the East Coast of the U.S.

In underwater observation using an autonomous underwater vehicle (AUV), a support vessel typically monitors the AUV to support the observation. The AUV have to be positioned to be tracked by the vessel and informed the positioning result for navigation with acoustic communication. This process is significant especially in deep water. The AUV uplinks to inform its status and transmit some observation data in real time, and sometimes be commanded to change the observation plan by downlink from the vessel. Authors planned to use an autonomous surface vehicle (ASV) to track and monitor multiple AUVs for efficient observation. An acoustic multi-access communication and positioning system have developed as one of the elemental technologies for the observation system. The developed acoustic system achieves multi-access with frequency division multiple access (FDMA) method, and the ASV can monitor up to three AUVs simultaneously. Positioning is performed with super short baseline (SSBL) method. The acoustic device has operation mode in which positioning and communication functions are integrated, called as auto mode. In auto mode, uplink packets can be very close and the AUV can uplinks efficiently, and timing of downlink is calculated from positioning result appropriately. Results of two sea trials are shown. The precision of positioning was enough to track the AUV. However random error was much larger than that of SSBL of the vessel, hence some precise method is necessary to keep the quality of observation data high. Communication and auto mode sequence worked well in the sea trial.

An innovative electrically operated automated Quad-maran is developed in this study. The vessel consists of 4 hulls and each hull is capable of yawing independently around its axis. The vessel is expected to sail and carry out environmental measurements automatically in waters like oyster farms, with an outstanding efficiency and brilliant energy-saving characteristics. An elemental research was first carried out to investigate the vessel’s resistance and propulsion performance as well as its electric energy consumption during sailing. Water tank tests were implemented on the actual hulls. Later, sea trials using the whole vessel were carried out in Ishikawa Prefecture, Japan, where the vessel sailed under remote control from a PC far away. Pool trials were also carried out. In this paper, detailed information is given on the design and working features of the Quad-maran automated vessel. Results of the tests and trials are evaluated, and the interference between hulls observed during tests is discussed. The electric energy consumption and as well as the relating efficiency are calculated and discussed.

In the case of vessels are moored at the quay, the drift and the wash up to the quay due to the broke of mooring lines is occurred by the tsunamis. In the previous study, the authors are examined to the applicability of the proposed tsunami protection measures as the install more mooring lines (IMML) and the floating tsunami protection wharf (FTPW). However, the Fender influences were not considered in previous authors studies. In this study, the fender influences are considered on the numerical simulation. The three-dimensional MPS (Moving Particle Semi-implicit) method is used as numerical simulation method. The linear compressing spring model is used as the fender model. The fender influences were investigated against the influences of tsunami protection measures using IMML and the damage status of vessel.

A vessel-shaped fish farm concept for open sea applications has been proposed recently. The whole system consists of a vessel-shaped floater, fish cages positioned longitudinally along the floater, and a single-point mooring system. The whole system weathervanes; this feature increases the spread area for the fish waste. However, the downstream cages may experience reduced water exchange when the vessel is parallel to the currents. This situation may jeopardize the fish health. A dynamic positioning (DP) system may be necessary to improve the flow conditions. This paper investigates the misalignment angle between the heading of the vessel-shaped fish farm and the currents under combined wave and current conditions. The misalignment angle is critical for the estimation of the DP system consumption. A numerical model of the fish farm system with flexible nets is developed. Current reduction factors are included to account for the flow velocity reductions between the net panels. The heading of the system is obtained by finding the equilibrium condition of the whole system under each combined wave and current condition. An integrated method using metamodels is proposed and applied for the prediction of the misalignment angle for a reference site. The probability distribution of the misalignment angle between the vessel heading and the currents is calculated using the Kriging metamodel for the reference site. Based on the prediction, the requirement for the DP system to improve the flow condition in the fish cages is discussed.

Floating cranes are often used for the installation and maintenance operations for offshore wind turbines when they are located in deep waters. As the motions of the vessel being easily affected by external environments, accurate prediction of the motion of the system is important. In this study, first a numerical system based on basic multibody dynamics system is developed for estimation of the behaviour of the lifting operations using floating cranes. Next, on-site measurements are carried out for a lifting operation of a caisson using floating crane. Two numerical models were built with flexible and fixed connectors and validation was performed for the static displacement during lifting operation and the dynamic characteristics of the caisson in the stand-by condition. The static displacements during the lifting operation calculated with de developed tool agreed well with the measurement. The peak frequency of the cargo acceleration in y direction calculated with the flexible model was lower than that calculated with the fixed model. Both models approximately agreed with the measurement. Calculated acceleration of the cargo in x direction largely underestimated the peak frequency of the measurement for both flexible and fixed models. The use of the linear spring to model the wire rope including friction at the end is a possible contributor to the difference.

In March 2017, Statoil performed station-keeping trials in drifting ice in the Bay of Bothnia with two anchor handling supply vessels; Magne Viking and Tor Viking . The data collection included monitoring of ice conditions and response of Magne Viking during ice interaction events. The present paper describes numerical simulations of broken ice and intact ice interaction events with single point moored Magne Viking .

In March 2017, Statoil performed station-keeping trials in drifting ice in the Bay of Bothnia with two anchor handling tug supply vessels. The vessels Tor Viking and Magne Viking were used as Support vessel and Moored vessel, respectively. This paper describes the above mentioned marine assets, mooring analysis, mooring configuration, mooring and unmooring procedures, including quick disconnection system design and operation.

The manoeuvring capabilities of an escort tug are essential key-features with a view to an all-around design approach devoted to an optimum oriented framework. From the hull geometry settlement and propulsive solution definition, the ability to predict thoroughly the operative life in terms of handling, effectiveness, and safety becomes fundamental, even more with the perspective of developing smart control logics supporting the masters. With such an aim, the availability of a reliable manoeuvrability model is of fundamental importance. In this context, it is important to define an optimum set of captive manoeuvrability tests, whether experimental or numerical, in order to correctly identify the vessel escort performances in simulation; this, always keeping in mind the necessity to limit the effort in view of an application at an early-design stage. Starting from a wide experimental matrix, purposely designed and realized, the present investigation focuses on the quality and robustness of the different regression manoeuvrability models by letting vary the subsets of tests, in order to determine, finally, which is the most suitable hull model to be adopted and which is the minimum set to be performed.

Floatover method has been proven a competitive installation technology in last thirty years. However, floatover installation is subject to a variety of technical challenges. Apart from weather restrictions, motions and position of the topside and deck transport vessel (DTV) should be strictly controlled during the entire installation operations. Therefore, a field monitoring system is essential to guarantee the installation safety. In this paper, a comprehensive introduction to the monitoring system developed by Shanghai Jiao Tong University is presented. The subsystems, including environment monitoring system, motions and position monitoring system, deck support units (DSUs) separating monitoring system, closed-circuit-television (CCTV) monitoring system as well as the integrated monitoring system (IMS), are proposed. Besides, the pre-installation surveys are also presented.

The Least-square support vector machine (LS-SVM) is used to estimate the dynamic parameters of a nonlinear marine vessel steering model in real-time. First, manoeuvring tests are carried out based on a scaled free-running ship model. The parameters are estimated using standard LS-SVM and compared with the theoretical solutions. Then, an online version, a sequential least square support vector machine, is derived and used to estimate the parameters of vessel steering in real-time. The results are compared with the values estimated by standard LS-SVM with batched training data. By comparison, sequential least square support vector machine can dynamically estimate the parameters successfully, and it can be used for designing a dynamic model-based controller of marine vessels.

An overview of data veracity issues in ship performance and navigation monitoring in relation to data sets collected from a selected vessel is presented in this study. Data veracity relates to the quality of ship performance and navigation parameters obtained by onboard IoT (internet of things). Industrial IoT can introduce various anomalies into measured ship performance and navigation parameters and that can degrade the outcome of the respective data analysis. Therefore, the identification and isolation process of such data anomalies can play an important role in the outcome of ship performance and navigation monitoring. In general, these data anomalies can be divided into sensor and data acquisition (DAQ) faults and system abnormal events. A considerable amount of domain knowledge is required to detect and classify such data anomalies, therefore data anomaly detection layers are proposed in this study for the same purpose. These data anomaly detection layers are divided into several levels: preliminary and advanced levels. The outcome of a preliminary anomaly detection layer with respect to ship performance and navigation data sets of a selected vessel is presented with the respective data handling challenges as the main contribution of this study.

This paper presents a motion planning, guidance and control system for an Autonomous surface vessel in a practical maritime environment. The motion planning algorithm is based in the angle-guidance fast marching square method and the guidance system is based in the line-of-sight trajectory tracking algorithm. To validate the motion planning algorithm, numerical simulations were carried out to compute the optimal path in a static environment including various obstacles. The guidance system was tested with an autonomous surface vehicle tracking a pre-established trajectory including static obstacles. The autonomous surface vehicle is a self-propelled scaled ship model of 2.5 m equipped with sensors and actuators, inertial measurement unit, GNSS positioning system, propulsion DC motors, and wireless communication. From the experiments and numerical simulations, a good agreement was found.

A general framework to support the navigation side of autonomous ships is discussed in this study. That consists of various maritime technologies to achieve the required level of ocean autonomy. Decision-making processes in autonomous vessels will play an important role under such ocean autonomy, therefore the same technologies should consist of adequate system intelligence. Each onboard application in autonomous vessels may require localized decision-making modules, therefore that will introduce a distributed intelligence type strategy. Hence, future ships will be agent-based systems with distributed intelligence throughout vessels. The main core of this agent should consist of deep learning type technology that has presented promising results in other transportation systems, i.e. self-driving cars. Deep learning can capture helmsman behavior, therefore that type system intelligence can be used to navigate autonomous vessels. Furthermore, an additional decision support layer should also be developed to facilitate deep learning type technology including situation awareness and collision avoidance. Ship collision avoidance is regulated by the Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs) under open sea areas. Hence, a general overview of the COLREGs and its implementation challenges, i.e. regulatory failures and violations, under autonomous ships are also discussed with the possible solutions as the main contribution of this study. Furthermore, additional considerations, i.e. performance standards with the applicable limits of liability, terms, expectations and conditions, towards evaluating ship behavior as an agent-based system on collision avoidance situations are also illustrated in this study.

The present contribution aims to implement a new methodology to prevent Roll on-Roll off vessels (RO-RO) from causing severe scouring actions. The methodology combines field, experimental, theoretical and numerical tools exchanging information to establish the manoeuvre potential scouring damage. The main contribution is the introduction of a manoeuvre ship simulator to obtain variables that otherwise cannot be obtained in field studies. These variables, all related to ship’s propeller behaviour, are the rotational speed, the pitch ratio and the engine power during the whole manoeuvre. Results show an over-prediction of the theoretical and experimental axial velocity and maximum erosion depth, indicating their clear limitations and the necessity of accurate data to apply the method. The methodology used with the key incorporation of the manoeuvre simulator is revealed to be a very useful tool to study new manoeuvres (including the possibility to work with a single or a couple of tugboats during the docking and undocking manoeuvres) to prevent propeller scouring actions.

Depending on the type of support, vessels are classified as displacement, semi-displacement and planing. But all types of vessels are in the displacement mode when they operate at low speed. In planing, due to the supportive hydrodynamic pressure, the hull wetted surface area reduces leading to low frictional resistance and consequent increase in speed for the same power input. Planing vessels are used for different purposes such as for fast patrol, sport activities, service, ambulance, rescue and recreation. The use of stern flaps, both fixed or controllable, interceptors and integrated interceptor-flap in high speed boats has become an acceptable option to control the running trim of the vessel to enhance its speed and powering performance. The interceptor-flap changes the pressure distribution underneath the hull which in turn causes reduced resistance acting on ships aftbody. The integrated stern interceptor-flap effect on planing craft performance depends on its parameters and also on those of the craft. So, an in depth study on the hydrodynamic behaviour of integrated interceptor-flap is essential, before it is adapted to a vessel, to get the best performance during the craft operation. In recent years, the computational fluid dynamics (CFD) technique has proved to be accurate and robust for hydrodynamic calculation of high-speed planing hulls. The aim of this paper is to study numerically on the performance of planing hull fitted with integrated stern interceptor-flap configuration. These studies help in understanding the flow field and other parameters on resistance of planing hulls with different flap angles. The study shows that the interceptor-flap performs well compared to bare hull. The guidelines that could be derived from these studies help in improving the interceptor-flap design for a high speed planing craft.

This paper attempts to present a mathematical model to predict hydrodynamic coefficients of a heeled planing hull in vertical plane. This model has been developed by using 2D+T theory and theoretical solution of the water entry of wedge section bodies. Sectional hydrodynamic force acting on the vessel is determined and then extended over the entire length of the vessel. By simplifying final equations of heave force and pitch moment acting on a heeled planing hull, equations for prediction of hydrodynamic coefficients of the vessel are developed. Accuracy of the method is evaluated by comparing its results against previous empirical methods. It is seen that current method has reasonable accuracy in prediction of different hydrodynamic coefficients. Also, effects of heel angle on added mass, damping and stiffness coefficients are studied and discussed.

With the extension of the offshore drilling operations to water depths of 10,000 ft and beyond, the technical challenges involved also increased considerably. In this context, the management of the riser integrity through the application of computational simulations is capital to a safe and successful operation — particularly in harsh environments. One of the main challenges associated with keeping the system under safe limits is the recoil behavior in case of a disconnection from the well. The risk that an emergency disconnect procedure can take place during the campaign is imminent, either due to failure of the dynamic positioning system or due to extreme weather in such environments. Recent work [1] in the field of drilling riser dynamic analysis has shown that the recoil behavior of the riser after a disconnection from the bottom can be one of the main drivers of the level of top tension applied. Tension fluctuations can be very large as the vessel heaves, especially in ultra-deep waters where the average level of top tension is already very high. In order to be successful, a safe disconnection must ensure that the applied top tension is sufficient for the Lower Marine Riser Package (LMRP) to lift over the Blow-Out Preventer (BOP) with no risk of interference between the two. This tension should also not exceed a range in which the riser will not buckle due to its own recoil, that the telescopic joint will not collapse and transfer undesirable loads onto the drilling rig or that the tensioning lines will not compress. A good representation of such behavior in computational simulations is therefore very relevant to planning of the drilling campaign. A case study is presented herein, in which a recoil analysis was performed for a water depth of 11,483ft (3,500m). Numerical simulations using a finite element based methodology are applied for solving the transient problem of the riser disconnection in the time domain using a regular wave approach. A detailed hydro-pneumatic tensioning system model is incorporated to properly capture the effect of the anti-recoil valve closure and tension variations relevant during the disconnection. A reduction of conservativism is applied for the regular wave approach, where the maximum vessel heave likely to happen in every 50 waves is applied instead of the usual maximum in 1000 waves approach. ISO/TR 13624-2 [4] states that using the most probable maximum heave in 1000 waves is considered very conservative, as the event of the disconnection takes place in a very short period of time. The challenges inherent to such an extreme site are presented and conclusions are drawn on the influence of the overall level of top tension in the recoil behavior.