Due to the increasing pressure from stricter environmental regulations to reduce emissions in shipping, the maritime industry has been striving for finding more effective measures. Existing measures are often not enough to comply with new regulations. Among various alternative measures, it is not easy for decision-makers (shipowners and operators) to choose the most suitable alternative measure as

In this article, selecting an appropriate mooring system for the spar platform of a wind turbine consisting of chain–cable–chain is investigated based on a meta-heuristic method. A boundary element software is applied to hydrodynamics analysis, and the numerical results are verified by experimental results. According to the characteristics of the experimental mooring system, an appropriate chain is

Unmanned underwater vehicles require a hull resistant to immersion and, therefore, to hydrostatic pressure, which places high demands on its design, manufacture and inspection, where dimensional control is a fundamental part of the verification of the shapes of the structure. In this research, a comparison is made of the dimensional control techniques currently used for the naval sector and their viability

The oblique wave reflection by horizontally stratified porous absorber having two horizontal porous bars of different porosities and friction factors placed on step-type bottom is studied using eigenfunction expansion method based on linearised wave theory. The present study examines several structural configurations such as porous absorber consisting of finite and semi-infinite thickness with/without

Point absorber wave energy converter is one of the most effective wave energy harness devices. Most of the wave energy converters generate energy by oscillating the floating body. Usually, the power-take-off system is simplified as a linear spring and a linear damper. However, the narrow frequency bandwidth around a particular resonant frequency is not suitable for real vibrations applications. Thus

The emergency pipeline repair technology is crucial to the maintenance and safety of pipelines under the emergency condition. In the offshore industry, the marine spherical isolation plug, a novel active plug device, is a significant emergency repair equipment of the hot tapping and line stop operation. In this article, the structure scheme and operation process of the marine spherical isolation plug

It is of paramount importance to determine the lightship characteristics of a newly built vessel correctly. Conventionally, an inclining experiment is performed after the ship is launched in order to determine the lightship GM and in turn KG values. However, there has been an ongoing debate about the validity of the results since it bears some assumptions during the test and calculation procedure.

The application of surface-piercing propeller (SPP) has been widely used in high-speed crafts due to possessing many favorable features. Due to the information gaps in the design of SPP, researchers have made great efforts to conduct hydrodynamic analysis of these propulsion systems. Despite the previous studies, there is still a considerable shortage in literature. In this article, a comprehensive

This article studies water wave interaction with a submerged quarter-circular breakwater based on potential theory and multipole expansion method. The obliquely and normally incident waves are independently considered. The series solution of velocity potential in the external fluid domain is expressed through the multipole expansions, while the series solution of velocity potential in the quarter-circular

We suggest a constrained H∞ control scheme for gyroscopic marine vehicle stabilization systems with output and control constraints. The H∞ performance is used to measure the roll angle reduction of the vessel relative to wave disturbances in regular beam seas. Time-domain constraints, representing requirements for precession angle of gyroscopes and for actuator saturation, are captured using the concept

Large two-stroke marine diesel engines are used as the prime mover in the majority of ocean going commercial vessels and are currently facing new stringent NOx emission reductions. Selective catalytic reduction is an aftertreatment technology which is able to reduce emitted NOx at allowable levels. In most marine applications, the selective catalytic reduction system is placed on the high pressure

In order to better understand the vortex-induced vibration mechanism of multiple cylinders, this article takes a relatively simple case of two staggered circular cylinders as the embarkation point and investigates their vortex-induced vibration characteristics by model test. The experimental Reynolds number ranges from 22,000 to 88,000. The in-line gap L is set as 3.0D, 3.6D, 4.2D and 5.5D in turn

The offshore drilling platform is the main equipment for oil and gas exploration. The increase in offshore drilling platform results in the apparently increased contradiction between oilfield exploitation and safe navigation of ships. In order to ensure safe navigation and the normal exploitation of oil and gas fields in a limited space, it is necessary to quantify the distance between ships and coastal

Given the importance of the communication energy consumption of multiple autonomous underwater vehicle cooperative systems in practical work, this work optimizes the network topology to reduce total energy consumption. In accordance with the characteristics of underwater communication, the energy consumption of communication links is obtained, thereby obtaining the total communication energy consumption

The unmanned surface vehicles have been used most frequently in recent years in different applications, like environmental research. For this vehicles to accomplish their autonomous missions, a path-following algorithm is necessary to reduce the cross-track error in the presence of environmental disturbance. This article presents a control scheme based on the path-following nonlinear guidance law for

The maneuvering characteristics of the unmanned surface vehicle itself are very important to motion planning due to the limited water scale area. If the size, motion state, and maneuvering characteristics of the unmanned surface vehicle are not considered, the shortest path obtained is actually not feasible in the restricted waters. In this article, the widely used A* algorithm is improved by accounting

This article presents an integrated risk assessment methodology for maintenance prediction of oil wetted gearbox and bearing in marine and offshore machinery with emphasis on ship cranes. Predictive maintenance uses important parameters measured in the equipment to ‘feel’ when breakdown is eminent. This type of maintenance intends to make interventions on machinery before harmful events may occur.

Liquid sloshing inside a tank with a slotted porous screen at the center is studied based on numerical and experimental methods. Slotted screens with three different porosities (0.0964, 0.1968 and 0.3022) for two submergence depths of 1 and 2 cm have been considered. One of the main advantages of the slotted screens is that the resonance frequency of the sloshing tank can be altered and the sloshing-induced

This article presents an experimental study on the “vortex-induced motion” responses of a moored “semi-submersible without catenary riser” and “semi-submersible with catenary riser.” An eight-point catenary mooring system is adopted for the study in which eight rollers are installed on the pontoons for guiding the mooring lines and the semi-submersible design is of two rectangular pontoon and two circular

Vortex-induced vibration of two tandem circular cylinders with different diameters under low Reynolds number (Re = 200) is investigated numerically by solving the uncompressible two-dimensional Navier–Stokes equations. The arbitrary Lagrange–Euler method is used to simulate the movement of mesh. Effects of diameters and gap ratios are considered. Numerical results show that diameter ratios and gap

This study aims at the parametric investigation of the gas injection system settings of a large marine two-stroke dual fuel engine by using a developed and customized CFD method in the ANSYS Fluent software. The investigated engine injection system parameters include the gas injection timing, the gas injection duration, the gas injector lateral angle, and the gas injector holes number. Based on the

Ferries are usually used for transporting passengers and vehicles among docks, and any deviation of the course can lead to serious consequences. Therefore, transportation ferries must be watched closely by local maritime administrators, which involves much manpower. With the use of historical data, this article proposes an intelligent method of integrating artificial potential field with Bayesian Network

In this article, noise spectrum of marine propellers is investigated in uniform flow under non-cavitating and cavitating conditions. New results are presented for this research field. Hydrodynamic performance of both non-cavitating and cavitating marine propellers is first analyzed by viscous and potential based flow solvers. In viscous solver, sheet cavitation on propeller blades is simulated with

Marine biofouling is a serious environmental problem, while traditional chemical antifouling is less environmentally friendly. Biomimetic antifouling is able to overcome this issue by restraining the growth of biofouling at the very beginning, while the current research interest in this field focuses on the dynamic antifouling layers. In order to construct a flowing layer on the surfaces of marine

Although shipping has significant positive effect on human civilization, it introduced negative environmental impacts such as oil, air, and plastic pollutions. Many negative externalities through international and local regulations have been in place, and preventive actions have been taken to monitor and control. However, underwater noise pollution as an emerging negative shipping impact has not been

This article presents an experimental study on the water entry of twin wedges commonly used as sections of catamaran craft. A twin wedge is a combination of two single asymmetry wedges connected by so-called wet-deck. The single asymmetry wedge has a vertical side and a non-vertical side with a range of deadrise angles. This study is carried out on a set of twin wedges of 7°, 15° and 20° deadrise angles