Surf-riding/broaching is one of the five stability failure modes newly included into the Second Generation Intact Stability Criteria by the International Maritime Organization. It is considered to be the most complex one among the five failure modes due to its strong nonlinearity and chaotic characteristics, hence having high academic research value. This paper introduces the researches related to the surf-riding/broaching in recent years, elaborates the research progress of the theoretical prediction, numerical simulation, model test and specifications, as well as the research developments concerning the influence of the surf-riding/broaching on the ship design and ship operation. The key problems that have not been fully solved and the bottleneck technologies that need to be broken are analyzed based on the state-of-the-art of the ship surf-riding/broaching. It can provide references for the key research directions in the future.

The bending failure of the sea ice occurs in the form of radial and circumferential crack during the contact loading of an icebreaker with the sea ice. The radial-before-circumferential cracking pattern of the sea ice will result in different ice loads compared to the circumferential-before-radial cracking pattern. It is therefore necessary to identify the bending failure mode of the sea ice under different contact loading conditions. The governing equations are normalized based on the theory of thin plates on elastic foundation under three operation conditions: the contact loading between the bow of the icebreaker and the linear boundary of the sea ice linear boundary, the contact loading between the bow of the icebreaker and the concave boundary of the sea ice, and the contact loading between the side of the icebreaker and the linear boundary of the sea ice. By solving the normalized governing equations with finite element method, the bending failure modes of the sea ice under different operation conditions are analyzed to obtain the criteria of the bending failure of the sea ice under the above three operation conditions. The results indicate that a circumferential-before-radial cracking pattern is easily to be caused with larger contact area between the hull and the sea ice and thinner ice thickness. On the contrary, a radial-before-circumferential cracking pattern will be easily caused.

Propeller is the core component of a ship. The performance of the propeller of an icebreaker is directly related to the speed/power performance, ice-breaking performance, vibration and noise performance and safe navigation performance of the whole ship. The design of the ice class propeller is therefore the key stage during the design of the icebreaker. It is necessary to ensure that the performance of the propeller can meet the design requirements. Different from the conventional propeller that operates in the open waters, the ice class propeller operates in the ice waters. The impact of the ice on the propeller should be considered during the design of the ice class propeller. However, there is little experience of the ice class propeller design in China. The ice class propeller design process (IPDP) has been established based on the analysis of the characteristics of the ice class propeller in the current study. The design results and model test results of the ice class propeller of a PC2 heavy icebreaker are presented. The results show that the design process of the ice class propeller is different from that of the conventional propeller with special focuses on the iterative design of the propeller parameters and hull parameters, due to the heavy load and multi-working conditions of the ice class propeller. It is necessary to verify not only the speed/power performance and vibration performance in the open waters, but also the speed/power performance and propeller strength performance in the ice regions. A detachable fixed pitch propeller is designed for the high ice class propeller to facilitate the repair and replacement of one single blade.

The motion and stability of the ship under the marine environment is a full nonlinear dynamic system. Considering the nonlinear characteristics of ocean environmental loads on the ship and the natural nonlinear response characteristics of the ship motion, there are extensive studies and a series of theoretical and application results. The research methods of the nonlinear motion response and stability of ships based on the theory of nonlinear dynamics are summarized, thus revealing the nonlinear dynamic characteristics of the whole process of the ship motion instability, large-scale motion response, and even capsizing. It mainly focuses on the nonlinear analysis methods and main conclusions of the parametric rolling and surf-riding/broaching in regular and irregular waves. The combination of the nonlinear dynamics method and the seakeeping theory in the current study provides a new approach and method for the study of the ship motion and stability.

The influence of the shape and the size of the moonpool on the vulnerability criteria assessment of the parametric roll and the excessive acceleration in the second generation stability has been analyzed for a drillship. This article considers the drillship with three moonpools of different opening shapes and different sizes to verify and analyze whether the drillship meets the second generation intact stability criteria under development. The analysis results indicate that the variation in the shape and size of the moonpool can affect the parameters of the vulnerability criteria of the parametric roll and the excessive acceleration for the drillship. The drillship with the moonpool of the shapes and sizes considered in this study can meet the criteria requirements. It can provide reference for the design of the drillship's moonpool.

The gas accumulation after the leakage of the nitrogen generator may cause the potential safety hazard. It is therefore necessary to set up the gas curtain around the Nitrogen generator to isolate it from the environment of the machinery space. The numerical simulation method is adopted to analyze the influence of the wind speed at the air outlet of the air curtain device on the flow field around the nitrogen generator. The results show that when the wind speed at the secord air outlet of the air curtain is 6.5 m/s, the air curtain at the bottom of the machinery space has poor isolation effect, leaving the gas hold-up region inside the air curtain device. The isolation effect of the air curtain can be increased by adjusting the wind speed at the secord air outlet to 8 m/s. At the same time, the influence of the vortex on the air curtain can be effectively reduced by adjusting the height of the central area inside of the air curtain device.