An experimental platform of an unmanned planning craft equipped with multiple sensors and control systems is proposed aiming at the insufficient system verification and evaluation of the path planning and obstacle avoidance control of the unmanned surface vehicle in real environment. The developed experimental platform integrates the LiDAR, depth camera, global positioning system(GPS), ultra wide band (UWB) positioning system, gyroscope and other sensors, and uses main controllers and bottom controllers based on the robot operating system(ROS) and Free_RTOS operating system. The experimental platform consists of the planing craft itself, the sensing system, the bottom controller and the remote monitoring system, including the upper positioning algorithm, the path planning algorithm and the actuator control algorithm. A comprehensive experimental platform including mapping, positioning and remote monitoring is built on the unmanned planning craft equipped with various sensors. The effectiveness of the path planning and obstacle avoidance control algorithm is verified by the navigation experiment of the planning craft. It is supposed to provide theoretical references for the technological development and application of unmanned surface vehicles.

Marine selective catalytic reduction (SCR) technology is an efficient NO _X removal technology, which has been widely applied in shipbuilding industry. However, the marine SCR technology also needs to be adjusted with the continuous improvement of the environmental requirements and the changes in marine energy structure. Nowadays, most marine SCR technology uses Urea-SCR technology, which is greatly affected by impurities in the marine fuel oils and the temperature of the exhaust. The high level of sulfur and alkali metals in the marine fuel oils has significant toxicity on catalysts, limiting the use of marine SCR. The diesel engine that mainly used on ships determines the range of the temperature change of the exhaust, which finally affects the denitrification of the exhaust gas through the influence on the effect of urea hydrolysis to produce ammonia, the layout of the SCR rectors and the catalyst activity. The above situation indicates that the design of an LP-SCR system with exhaust gas heating will be an important direction of the design of the SCR for the ships using marine fuel oils as fuel. It is critical to find safe source or method of supplying ammonia with high production efficiency and precise control for the development of marine SCR systems. Improving the fuel quality and reducing the toxicity effect in the smoke can provide a foundation for the research and development of new low-temperature and anti-toxic catalysts. The low-carbon and zero-carbon fuels become a global trend due to carbon neutrality, resulting in different exhaust emissions after combustion and then the change of SCR control technology. The zero-carbon and low-carbon fuels have single and reducible composition, and have the potential to be SCR reducing agents. The integrated processing SCR technology that uses the fuels itself for NO _X removal will become an important direction for the development of marine SCR under the goal of carbon neutrality.

The design ideas of ship epidemic prevention and safety heating ventilation and air conditioning （HVAC）systems are provided by summarizing the characteristics of the onboard infection outbreak and comparing the requirements of classification societies on the arrangement of isolation cabins and the HVAC technology, in order to mitigate the onboard infectious disease transmission. The results show that the isolation cabins equipped with epidemic prevention and safety HVAC system can effectively mitigate the transmission of virus through contact and air. The epidemic prevention notation of each classification society has different requirements for the design of HVAC system. The BIOSAFE SHIP is a notation developed for onboard epidemic prevention by RINA, which is accumulatively evaluated and scored according to the biosafety risk factors of the HAVC system and other systems. The notation Infectious Disease Mitigation-Arrangements（IDM-A）of ABS provides three kinds of negative pressure isolation cabins capable of being switched from its normal operation mode to an outbreak operation mode, with specific requirements of the ventilation system layout, pressure differential, air changes per hour, pipe fitting and operational measures for negative pressure cabins. The notation Epidemic Prevention and Control （EPCN）of CCS presents requirements of the ventilation system layout, airflow organization, pressure differential, air filtration, pipe fitting, operational measures and exhaust outlet for negative pressure rooms. It can provide references for the epidemic prevention and control on board marine and offshore assets.

A series of technical problems of “ice-breaking, winterization and scientific research” in the construction process of the “Xue Long 2” are summarized in order to systematically solve the bottleneck of Chinese polar ship construction technology in the future. The key points of the ice-breaking structure construction, the winterization design and the installation of the polar research equipment are reviewed from the construction process of the assembly plant, achieving technical breakthroughs in the construction of the polar research icebreaker. It also proposes the key points of structure construction technology optimization and winterization protection system design, and preliminarily set up the fine construction technology system for the polar research ship lifecycle. The advance research of the construction technology of a heavy icebreaker is also carried out to put forward further research interest.

The second-generation intact stability criteria of International Maritime Organization (IMO) has entered the trial period. This paper focuses on the surf-riding/ broaching stability failure mode in irregular waves. It reproduce the process of the surf-riding/broaching phenomenon through massive repeated numerical simulations with different speeds, wave directions, wave spectrum truncation ranges and metacentric heights ( GM) by adopting a six degrees of freedom (6-DoF) numerical modeling. Hilbert transform is used to calculate the instantaneous wave velocity to identify the ‘speed increase’ state, and the probability of ‘speed increase’, broaching, excessive yawing and rolling are quantitatively studied. It is found that the occurrence of ‘speed increase’ is closely related to the surf-riding, and its probability estimates increase with the increase of the ship speed. Most ships capsize after experiencing a relatively long and continuous duration of ‘speed increase’, and the wave spectrum frequency truncation has a great impact on the probability estimates of ‘speed increase’. However, the probability estimates of broaching after ‘speed increase’ increase sharply with the increase of the wave angle for the ships at the same speed. The total duration of broaching can account for 30% to 50% of the total duration of ‘speed increase’ at high speed when the wave angle reaches 30 degrees. With the increase of the ship speed, the proportion of the duration of broaching in the total time of excessive yawing gradually increases to 60% to 80%, indicating that the yawing at high speed is mainly caused by broaching. The same as the variation of the probability of broaching after ‘speed increase’, the probability estimates of excessive rolling also increases with the increase of wave angle. The quantitative probability estimates of the ‘speed increase’, broaching and excessive yawing and rolling can provide technical support for the application of the second generation intact stability criteria of IMO.

The application status of main marine refrigeration units and the refrigerant has been analyzed in order to promote the process of the ship greenhouse gas emission reduction. It summarizes the usage and restrictions of the marine refrigerants by the environmental labels of the classification societies, the development of the marine refrigerants and the marine low global warming potential (GWP) refrigerant with application potential. The results show that the main marine refrigeration system currently uses the steam compression refrigeration, and the commonly used refrigerants are R134a, R404A, R410A, R407C and R407F. The environmental labels of CCS, DNV GL, ABS, BV and LR require the Ozone depletion potential (ODP) of the marine refrigerants to be zero, and the environmental labels with the higher level require the GWP of the marine refrigerants less than 2 000. Special consideration of flammability and toxicity are required for the refrigerants with flammability and toxicity. The marine low GWP refrigerants mainly include the hydrous ferric oxide (HFO) refrigerant R1234yf, the HFO mixed refrigerant series of R449A, R513A and R454, and the natural refrigerants of NH ₃ and CO ₂. The results can be used as references for the design and study of the marine refrigeration system.

Turret is the common mooring scheme and the key part of the floating production storage and the offloading (FPSO), whose ventilation system requires to be focused on. Most of the technologies and patents of the turret are currently mastered by a few foreign companies, imposing a long-term technological blockade on China. This paper proposes the design scheme of the ventilation system of the FPSO in detail, and carries out the numerical simulation by the computational fluid dynamics (CFD). This design scheme innovatively utilizes the bearing wheel gap and the opening of the turret itself for the forced ventilation, which realizes the effective ventilation of the turret. The design scheme and the analysis method have the accumulated valuable experience, which are of great significance to China’s independent design of the FPSO turret in the future.

For the working ships without power, the mooring system not only meets the requirements of the positioning of a ship, but also enables the ship to move. The moving and rotating operations of a cutter suction dredger are analyzed in the time-domain based on the three-dimensional potential theory. An appropriate mooring system is then designed to ensure the economy of the ship operation. It provides reference for the design of the enginearing ship operation system.

Lean production is an optimal combination of resources of manpower, machine, material, method and environment to achieve the maximum output benefit with the lowest resource input. The improved plan has been developed based on the lean production theory by analysis of the problems in the current production of company A, such as the inconsistency of the material plan, the manpower plan and the production plan, and the high stocks. The lean production supply chain is then achieved through the establishment of the logistics system of planning and the improvement of the lean design, as well as the implementation of the consistency of the material plan, the manpower plan and the production plan.