A software has been developed to predict the inherent longitudinal vibration characteristics of the ship shafting. The software is developed using the QT platform, with the core solver written in MATLAB and the solution algorithm using the Holtz method. The results are compared and verified with the simulation results of ANSYS and the longitudinal vibration calculation results of an actual shafting system. On this basis, the developed software is used to discuss the variation of the longitudinal vibration characteristics of the shafting under different shafting properties. The results show that the properties affecting the inherent longitudinal vibration characteristics of the shafting mainly include the crank radius, crank thickness, longitudinal stiffness of thrust bearings and material elastic modulus. The relevant research results can provide references for the vibration and noise reduction of the ship shafting.

The maneuvering of ships sailing in Polar Regions is much more complex than those in conventional waters, imposing hazards on ships sailing in Polar Regions. However, there are currently few analysis and research on the characteristics and maneuverability design requirements of polar icebreakers. This study introduces the polar environment related to the maneuverability of icebreakers, such as the wind, wave and current, shallow water, narrow waterway, low temperature and low visibility. It also analyzes the classification and ship characteristics of the icebreakers in Russia and other countries, and summarizes the relevant requirements of maneuverability standards for maneuvering devices on ice breakers with pod, multi-propeller and multi-rudder. In order to meet the requirement of maneuverability design, it introduces the maneuverability research methods such as the model test, full-scale test and numerical simulation of ice breakers, and the calculation methods for the ship-ice interaction forces such as the empirical formula method, finite element method and discrete element method. The above analysis and summary can provide references for the maneuverability design of icebreakers.

Stabilizing systems are necessary for the ship in wind and waves to ensure stable operations and improve the safety and comfort of the crew.As an effective stabilizer, gyrostabilizer acts entirely within the hull without requiring sufficient movable weight to generate a control moment. The nonlinear wave force disturbance model of the ship in random waves is firstly established. The combined dynamic model of the ship and the gyrostabilizer is then built together with the working principle of the gyrostabilizer. The corresponding MATLAB Simulink block diagramsof the ship motion control are constructed for two kinds of gyrostabilizer models, i.e., the natural-driven gyrostabilizer model and the controller-driven gyrostabilizer model. The results show that both the natural-driven and controller-driven gyrostabilizer are able to reduce the rolling motion through the gyroscopic effect of high-speed spinning and precession angel variation. The controller-driven gyrostabilizer can reduce the nonlinear rolling motion of the ship more effectively than the natural-driven gyrostabilizer.

The International Maritime Organization (IMO) developed the second generation of intact stability criteria, which includes the parametric rolling. In the direct stability assessment, numerical simulation is the most direct method to study the rolling response and stability. However, the analytical analysis method is still necessary because ship capsize is a rare event. The stochastic averaging method of energy envelope can accurately solve the random motion response under the excitation of white noise. However, real waves in the practical engineering correspond to a narrow-band spectrum. The research on the applicability of the stochastic averaging method shows that the system damping and the excitation intensity should be small enough and the excitation bandwidth should be large enough for the non-white noise excitation. An improved method of the stochastic averaging method of energy envelope under the narrow-band spectral excitation is studied based on the above situation. The phase angle is introduced into the original stochastic averaging method of energy envelope by referring to the standard stochastic averaging method. The nonlinear restoring force can be considered, and the limitation of the ideal white noise excitation required by the original method is relaxed to make it possible for the narrow-band excitation. The stationary probability density function (PDF) of the roll angle obtained by solving the Fokker-Planck-Kolmogorov (FPK) equation agrees well with that of the Monte Carlo method. The improved stochastic averaging method of energy envelope can accurately calculate the rolling response of the ship under the excitation of real waves and evaluate the ship roll stability. It can provide guidance for the safe navigation of the ship.

The automatic control model test platform based on 6-DoF optical system has been developed according to the model test demands for the automatic control of the two-ship lateral replenishment at sea. This article elaborates the composition, function and usage of this test platform, analyzes the characteristics and advantages of the platform compared with those of the conventional ones. The test platform is used to perform the two-ship lateral replenishment model tests in a large towing tank for the validation of the test platform. The current research lays a solid foundation for the application of the automatic control technology in the two-ship lateral replenishment at sea. It can also provide reference for the research and development of such advanced test platforms.

Plough-in at high speed is one of the three unique potential hazards for the air cushion vehicle (ACV). The anti tuck-under ability of ACV bow flexible skirt is the key technical measure to avoid the serious consequences caused by the occurrence of plough-in. The three-dimensional (3D) model of the bow flexible skirt is established to calculate its anti tuck-under capability based on the secondary development of CATIA. This model can easily take into account the influence of the skirt cylindrical fore-face, the two side-ear flaps and the transiting arc from the fore-face to the side-ear flap, with the more accurate description of the actual structure of the skirt. The capability of the anti tuck-under of the bow skirt can then be evaluated more precisely to promote the design of the skirt and to guarantee the navigation safety.