The experimental studies in the ice model tank of the Krylov State Research Centre are described in the paper. This study aimed at researching a possibility of close-coupled towing of large-sized vessels by icebreaker. The displacement of considered commercial vessels is several times greater than the icebreaker displacement. Due to the fact that an amount of cargo transported along the Northern Sea Route is growing every year and new terminals are being constructed for the export of raw materials extracted in the Arctic, it has been shown in the paper that new transport vessels with high cargo capacity should be designed and built for the efficient operation of terminal. It has also been shown that the organization of independent year-round operation of such vessels in the Arctic region is extremely difficult, therefore, even at the stage of their design it’s important to consider the possibility of their escorting by existing icebreakers. The feasibility of close-coupled towing in the escorting of large-sized vessels with low ice class by icebreakers in the Arctic waters has been studied in the paper. The models of the greatest existing nuclear-powered icebreaker and conditional bulk carrier are used as an object of the ice model tests. The study of the close-coupled towing features in the continuous flat ice conditions is carried out at straightforward movement and gyration, as well as for the case of an emergency stop of the icebreaker. During ice model tests the ice forces acting on the hull of the model are measured, as well as the load on a towing notch with rubber fenders in the stern of icebreaker and the tension in the wire rope. The comparison of the wire rope tension with its breaking force is taken as a criterion to assess the possibility of the close-coupled towing operation. The results can be used as the basis for choosing the hull concept of the future large-sized vessels, its ice class and main dimensions and in strategic simulations of Arctic marine transport systems.

The influence of technologies of automated processing of hydrographic survey results on the potential of the human factor in the transformation of polygraphic cartographic products into digital ones is analyzed. When configuring the digital bathymetric model, the concept of the navigation surface is used as a perspective principle of automated mapping. The approach to the problem of generating bathymetric contours from measurement results in the navigation surface paradigm is construed on continuous spline interpolation of geospatial data for reasonable cartographic generalization when creating electronic cartographic products. From the theoretical positions of the spline approach, the subjectivity of the method of artificial displacement of generalized isobaths to deep-water areas is excluded when creating a safe digital model of the bottom relief, interpreted in a mathematical sense as a navigational isosurface. The principle of electronic mapping based on the use of a spline in tension as an effective approach for the process of generalizing isobaths in order to obtain a wide range of morphometric characteristics of underwater topography has been developed. The generalized line of the active depth contour is estimated in the form of algorithmic reproduction on electronic charts of the safe convexity of the isobate towards the deep-sea area due to the practical implementation of the B-spline “snake model” by analogy with the serpentine configuration of the bathymetric isoline in the form of a piecewise polynomial function. When using the spline approach, an innovative principle of electronic mapping of the underwater landscape based on operating with a set of gridded data is implemented. The latter are interpreted as the results of depth measurements with the formalization of a two-dimensional frame of fixed values of bathymetric measurements for their representation as a navigational isosurface in three-dimensional Euclidean space. The actual synthesis of the seabed topography is implemented on the basis of a proven hybrid spline model for a specific indicative test case based on the processing of experimental gridded data. Hypothetically, the possibility of intellectual assistance to the watch officer in the strategy of instant orientation in conditions of a minimum depth reserve under the keel is organized when using computer three-dimensional visualization of the topography of the underwater relief in an unaffiliated graphic environment with foreign software.

According to the requirements of the International Convention for the Safety of Life at Sea (SOLAS-74) vessels must be equipped with Electronic Chart Display and Information System (ECDIS). This equipment is designed to improve safety of navigation and definitely has a number of indisputable advantages over the paper charts navigation. At the same time use of ECDIS requires navigators to have a sufficient level of competency for professional operation. Inadequate setting of safety parameters as well as incorrect interpretation of information from the display can lead to an accident. The determination of cross track limit (XTL) value as one of the route safety parameters in ECDIS is considered in the paper. Some companies navigational procedures are studied; it has been found out that companies have individual requirements regarding XTL value and they can vary. The issue of XTL value determination was recently studied and the authors of the previous research had proposed their own method of XTL calculation. This method is analysed in the paper and it has been concluded that this method is applicable for determining minimum XTL value, however in order to find the optimal value it is necessary to consider ship particulars and characteristics of a specific waterway as well as company requirements for under-keel clearance. The model structure, which integrates this information, is proposed in the paper, and the previously proposed method is used within the model. The model developed by the author is flexible: the input values can be adjusted, which allows to assess the safety of any size ship passage through any waterway. The incorporation of bottom contour information into the model through a piecewise function enables to assess the under-keel clearance for any values of XTL and to determine dangerous values of cross-track distance in particular conditions. The main disadvantage of the model is a necessity to define the piecewise function which adequately corresponds with the actual depth distribution in the waterway analysed, which restricts the application of this model to natural waterways with a difficult terrain of the bottom. It should be noted that with particular input values some «borderline cases» can take place, when the safety of passage is doubtful. In order to solve these uncertainties, the model can be later upgraded by including experts’ opinions with the use of fuzzy logic methods.

The dynamics of the development of the Lena polynya formed on the shipping routes of the Northern Sea Route in the Laptev Sea and its influence on the conditions of navigation in the Arctic are studied. During the period of winter-spring navigation in the Laptev Sea, the Great Siberian polynya, which is located near the fast ice border and creates good opportunities for winter navigation on the Northern Sea Route, is formed. This problem is important to ensure year-round navigation in the Eastern Sector of the Northern Sea Route. The hypothesis that the terms of a polynya occurrence can significantly affect the average rate of its growth is tested in the study. When checking, the results of the GLORYS12v1 global reanalysis and standard methods of mathematical statistics are used. On the example of the polynya section located on the estuary seashore of the largest navigable channel of the Lena River Delta - Bykovskaya, the validity of the hypothesis is confirmed. Steady trends in the change in the polynya formation terms towards earlier dates in the modern period are revealed. A high probability of improving the conditions of navigation in this region in 2020-2040 is noted. At the same time, with further warming of the Siberian climate, the opposite process, namely, the freezing of a polynya that formed too early, which will lead to a cooling of the climate in the region and a deterioration in navigation conditions, is possible. Comparing the results obtained with other studies that are devoted to the construction of general routes for ships in various ice conditions, it is possible to identify trends that the actual routes during independent navigation pass along the forming polynyas, regardless of the physical principle of their formation, then the choice of general routes for ships in the areas of polynya distribution will be promote more intensive and safe shipping. What requires accurate forecasts of its size and position. The relevance of the research results for forecasting year-round navigation, both for independent navigation of ships with a high ice class, and in the development of plans for using icebreaking escort of ships, is noted.

The efficiency of operation and interaction of “sea ferry/cruise company-sea passenger port-land transport infrastructure” systems directly depends on the dynamic influence of the external environment, which today determines the transition from deterministic models of decision-making to probabilistic ones. These changes on the basis of current trends in the industry in the form of the introduction of large cruise and ferry ships create the need to form a decision- making system for the reasonable modernization of infrastructure for the heads of ports and terminals. It is necessary to systematically modernize both the berthing infrastructure and change the internal processes of passenger handling in the terminal. The problems of forecasting the development of seaports in connection with the gradual recovery of passenger traffic, caused by a long period of restrictions due to COVID-19, are considered in the paper, as the first priority is the resumption of the route networks of the sea regions, which provide local passenger mobility. Based on the investigated models of ports and terminals evolution (Anyport model, Three Generations model, Workport model) it is revealed that today it is necessary to evaluate possible predictive scenarios of port development. The necessity of having the tools allowing to operatively analyze the situation in the sphere of sea ferry transportation and to model the scenarios of port congestion has been revealed and proved. The approach to estimate the variants of berths loading at simultaneous call of several big cruise vessels on the basis of models of mass service systems for subsequent estimation of infrastructure is considered in the paper. The object of the research is the Baltic Sea region and existing routes of cruise and ferry lines. A new theoretical partitioning of the region and sea passenger ports into four sections is proposed. The systematic analysis of all existing cruise and ferry line routes in each area has been carried out; data on cruise and ferry ship size, passenger capacity, average ticket price, and distance between terminals on the route have been presented. On the basis of the formed approach a new digital dynamic route map that allows both to investigate the current state of the route network and to estimate the possible changes is built. On the basis of the received data it is proved that the best development of passenger sea ports and terminals infrastructure is observed in the segment between the countries of Russia-Estonia-Finland-Sweden. Presented sea terminals have successfully realized the possibility of simultaneous reception of two big cruise vessels and modernized infrastructure during the period of restrictions on the reason of COVID-19, which corresponds to the formation of new points of growth in the Baltic Sea region, taking into account recovery of route networks. The generated big data on route networks accurately define the current state in the sphere of sea ferry/cruise transportation and they should be used in new digital simulation transport models when modeling different variants of sea passenger port operation, both at the stage of short-term planning and when solving the group of questions of development forecasting, which is especially relevant in the situation of competition between terminals for passenger traffic.

The process of training a neural network on calculation of closest point of approach (CPA) between two ships, and testing its performance and accuracy is described in the paper. The architecture of the neural network, the type of input and output data, and creation of training data set are also described in the paper. Feed Forward Neural Networks with Backpropagation algorithm are used; training method is Supervised with Levenberg-Marquardt algorithm. The input data are positions, courses and speeds of vessels in a certain area, the output data are Closest Points of Approach (CPA) between them. The process of writing a script in MATLAB software environment is described. The script allows a user to generate training data with any number of vessels in an area. Comparison of the time spent on CPA calculation using formulas and using neural networks is carried out. It has been proven that when processing large data arrays, the CPA calculation with neural networks is much faster than by means of formulas. After neural networks training process and the calculations results comparison, one neural network with mean squared error of 0.21 is chosen. It can be used for CPA calculations in MATLAB-based simulations. In the future this network might become a base for a collision-avoidance neural network system, which will allow vessels to manoeuvre safely in order to avoid collisions in a certain area.

The organization of transportation by inland water transport involves taking into account the overall characteristics and navigational features of waterways, the choice of a vessel to work on the route, ensuring the safety of navigation and the economic efficiency of the voyage. One of the main advantages of barge-towing combinations is the possibility of their formation according to the specified dimensions of the waterway. The purpose of this work is to overcome the linear approach currently used in the formation of the ship’s composition, and to develop mathematical foundations for describing the barge-towing combination control system, a particular task is to optimize the barge-towing combination structure for local restrictions of waterway sections. To solve this problem, the possibility of reorganizing the ship’s composition directly on the route, depending on the conditions for the passage of a particular section of inland waterways is supposed to study in the work; it in the future will improve the transportation efficiency and ensure the transportation of more cargo per voyage. For the mathematical description of inland waterways, their natural characteristics are used in the work, sections coincided in restrictive features are identified, that is, each section of inland waterways, depending on its type, has a certain set of restrictions related to overall characteristics that must be taken into account when organizing navigation. The simulation of the movement of a ship’s combination along sections of waterways of various types, including a curved section, performed by graphic-analytical methods, shows the limitations arising when entering a turn and passing through artificial narrowings of the fairway, and also reflects the ability to pass the entire route due to a change in configuration when maintaining the total carrying capacity of the ship’s combination. As a result, mathematical relations and a system of inequalities that determine the choice of a section of inland waterways for the operation of ship’s combinations in a certain (specified) configuration and planning their reformation according to the given characteristics of the waterway are obtained.

Equilibrium stranding of a ship is a necessary preliminary step for application of other decision support system algorithms, such as identification of a flooded compartment, predicting an emergency vessel capsize probability, and others. The equilibrium stranding using a real ship as an example based on the heel angle sensors readings for rolling and pitching, and the water column pressure sensors readings for the vertical roll, is calculated. In the linear case, the mean value of an individual value coincides with the equilibrium position on the corresponding coordinate axis. However, a ship rolling in a sea is, as a rule, non-linear process, and hence the mathematical average correction is required. The use of the Nechaev’s method for determining the equilibrium position of a floating vessel in a heavy sea is illustrated in the paper. An algorithm based on simulation modeling in the Virtual Testbed software package is proposed. It has been proved that complication of wave model used for coefficients obtaining in Y. I. Nechaev’s algorithm changes obtained equilibrium parameter value insignificantly, but in this case time spent for generation of one simulation is increased significantly enough. When using linear waves or Stokes waves, the generation of two minutes of simulation is faster than two minutes of real time; when using Gerstner waves, the simulation time approaching three minutes of real time, which already exceeds the simulation time. In this case, when using the Stokes waves model, it is possible to achieve the results closer to the Gerstner model than when using the linear waves model without consuming additional time. This fact allows us to conclude about the optimal use of the algorithm.

Propeller shafts and countershafts are bent quite often on sea and river vessels. The cause of the curvature is a strong load on this node of the ship’s power plant. In addition to bending, the shafting experiences longitudinal and transverse loads with a dynamic and static component. A large number of scientific papers have been devoted to the study of the dynamics of the propeller and shafting. However, the problem has not been completely solved, and the increase in damages during the shafting operation and its intensive wear only confirm the relevance of further research in this direction. The aim of the work is to determine the dynamic forces in the shafting, which occur during impulse action due to the propeller impact on the ice. A model of a two-stage elastic rod with inert disks at the ends is presented in the paper. It allows considering different situations of dynamic impact on the shafting and propeller. The following design features such as different stiffness of the shaft sections, different speed of elastic waves of deformation (different densities and modules of elasticity on the shaft sections), reduced inertial load from the moving parts of the drive, can be taken into account in the model. It is concluded that the frequency of the main form of oscillations mainly depends on the inertial loads concentrated at the ends and the shaft rigidity. The proposed simplified model of the inertialess shaft makes it possible to determine the angles of rotation of the shaft sections with sufficient accuracy. For different sections of the stepped shaft, the dynamic torque coefficient can differ significantly.

Currently, a new icebreaking fleet including universal nuclear icebreakers of the new generation of project 22220 is being intensively built in Russia. The nuclear icebreakers of this project such as “Arctic” and “Siberia” are already in operation. The “Ural” “nuclear icebreaker is almost ready for commissioning. “Yakutia” and “Chukotka” icebreakers as well as the icebreaker-leader of project 10510 are under construction. The integrated layout of the main equipment of the reactor plant had been used for the first time on the nuclear icebreakers of the new generation of these projects. The application of the new principle of equipment layout required switching to a fundamentally new method of forming the heat exchange surface of steam generators. As a result, straight-tube modular structures assembled into cassettes of steam generators were used. The approach to providing feed water supply and steam removal from steam generators has also changed, which significantly affects the thermohydraulic processes in the cassettes and leads to a decrease in the temperature of steam at the outlet of steam generators. In addition, the heat exchange surface of the modules in the longitudinal section forms annular channels with two-way heating by a coolant, which also affects the steam generators characteristics formation. In particular, the coefficients of heat transfer and heat transfer over the phase sections of heat exchange, the average logarithmic heat heads and the distribution of the heat exchange surfaces of the sections have changed compared to the previously used coil steam generators. At the same time, the hydraulic resistance of the flows through the working fluid and the coolant has decreased which reduces energy costs for pumping media and creates favorable conditions for improving natural circulation. In this paper, the task is to analyze the features of the thermohydraulic characteristics of steam generator cassettes, to compare them with similar characteristics of coil steam generators in operation.

The development of the method of preventive protection for the purposes of safe operation of the ship’s electric power system in emergency situations associated with malfunctions of its elements that occur during operation is considered in the paper. It has been shown that the existing devices form a command to start an emergency diesel generator at the moment when the voltage on the main switchboard busbars disappears. This circumstance causes a break in the power supply of responsible consumers of electric energy for a time equal to the start time of the emergency source. At the same time, the vessel loses control, and in most cases, the course. In this regard, it has been paid special attention in the paper to the development of a method for the preventive start of an emergency diesel generator, in which the launch command is formed before the vessel is de-energized, but with a real threat of this event. The conditions under which the preventive start of an emergency diesel generator should be carried out are formulated. Within the framework of the proposed approach, the energy state of the entire ship’s electric power system is predicted in the case of a decrease in its generating capacity, and, if necessary, a command to start an emergency source of electric energy is formed. At the same time, the most dangerous situation develops at a time when, in case of a failure of the generator unit of the main power plant, preventive unloading of the network turns out to be ineffective. It has been shown that there are emergency modes of vessel operation, such as flooding or fire in the room of diesel generators, in which the probability of simultaneous failure of all main electricity sources at once is especially high. The application of the proposed method of preventive start-up of an emergency power source will allow, in case of failure of at least one of the generator units of the main power plant operating in parallel, flooding or fire on the ship, to carry out structural adaptation of the system in advance to the malfunction that has arisen and go into a partially operational state, bypassing the emergency situation. At the same time, the interruption in the power supply of responsible consumers ensuring the safety of the vessel operation will either be significantly reduced or it will not happen at all. A functional diagram of a simple device implementing the proposed approach in practice is presented. A brief description of his work is given.

The purpose of the work is to apply automation technologies and digitalization of the process of assessing the immeasurable variables of the state of the river dredger automation system when controlling high-tech software and hardware equipment with an electric drive, in order to increase the productivity of the vessels of the technical fleet when performing dredging operations on waterways. River dredgers are complex dynamic control objects, the performance of which in the conditions of digital transformation can be significantly increased through the use of new software and hardware, the algorithmization of which is based on neural network technologies and learning processes. To increase the efficiency and reliability of the operation of such facilities with the prospect of transition to unmanned control of the energy systems of dredgers, it is necessary to increase the information content of the complex of sensors containing information about the object state. In this regard, the use, along with the existing ones, of mathematical information sensors, which are observers, is proposed in the paper. On the example of controlling a precision electric drive, an algorithm for synthesizing a dynamic system with an observer, in which all components of the state variables vector are restored at the output coordinate, is considered. The proposed algorithm for the synthesis of the state vector evaluator is implemented in the form of a program compiled in the MATLAB codes, and it is demonstrated by the example of calculating a three-dimensional dynamic observer for the automation system of a river dredger. The obtained values of state variables and errors of their recovery, as well as the results of modeling the dynamic reactions of the automation system of the river dredger, correspond to the specified speed and required stability of the electric drive of the river dredger during its transition to a steady state under new initial conditions.