The article presents a formula to estimate a safe distance for icebreaker escorting of ships with azimuth thrusters. The formula has been obtained using a simplified representation of the processes that occur during ship stopping in ice. Ice resistance of a ship in the channel behind the icebreaker has been calculated using empirical formulae that include the main design parameters of a ship, such as bollard pull, maximum speed in open water, and others. The article also contains an analysis of the influence of various factors on safe distance. The formula has been verified by the model experiment on the stopping of Yamalmax-type LNG carrier in the channel behind the Leader-type icebreaker in 1,5 m thick ice. In addition, the calculation results were compared the full-scale distances between the Christophe de Margerie LNG-carrier and leading icebreaker during a transit voyage along the Northern Sea Route in February 2021. Average full-scale distances have been found to be significantly higher than calculated safe distance, and more corresponding to safe distance in open water conditions.

The article discusses and analyzes the actual task of determining the location of LNG bunker fuel transshipment complexes. A method for solving this problem based on the Ardalan heuristic method has been proposed, while determining main factors influencing the economic efficiency of the fuel delivery system from the point of view of the bunkering company. Calculation results may be used in the technical and economic assessment of the newly created infrastructure and the scientifically based choice of the fuel delivery scheme depending on the volume. The proposed method can also be used to estimate the location of other enterprises servicing ships and having an unfixed service radius. The solution of the problem of determining the location of transshipment complexes of bunker liquefied natural fuel has also been given using the ports of the Baltic Sea as an example.

The article analyzes modern mechanism for ensuring qualification assessment in its current state. The field of professional activity of specialists performing diving and underwater work has been investigated. The tasks they solve have been formulated. An overview of the professional standard "Diver" has been given. The update of the standard has also been reviewed and a professional qualifications council that develops and updates the professional standard "Diver" has been established. Positive conclusion on the provision of a request for the labor market has been drawn and the documents regulating the formation of an independent qualification assessment system have been considered sufficient.

The article discusses the definition of parametric roll charatecristics based on the formula of V.V. Lugovskiy. An additional non-linear moment MX 24 is taken into account. Mathematical formulation of the problem has been given, together with its solution. Test calculations of parametric roll for five ships of different types: passenger ship, oil tanker, container ship, timber carrier and bulk carrier — have been given. Roll calculations have been performed at heading angles of 60°, 90° and 120°. RAOs for ships have been calculated with and without non-linear moment consideration. The calculations have been carried out for a given static stability diagram with frequency graphs built based on the Vlasov method. A significant influence of non-linear moment on the maximum amplitudes of parametric rolling have shown, especially for the ship positioned in beam waves, thus demonstrating the need to take the non-linear moment.

Inclination test is one of the most critical test phases for submarines and vessels. Its purpose is to determine the transverse metacentric height that characterizes the stability of the ship, and to adjust its value to the design value by changing the center of gravity of the ship via application of solid ballast. The basis of the inclination test is to determine the increments in inclination angles. The accuracy of angles measurements directly affects the accuracy of transverse metacentric height determination and stability of the ship as a whole. The article presents the results of practical application of new patent-protected recording instrument. In addition, method to process submarine inclination angles during the acceptance trials has been given, using the instrument under review, namely, the EU-1 electronic angle-measuring instrument. The article also provides comparisons with nearest analogues.

One of the most easily damaged structures of a ship when sailing in ice are the elements of the propeller-rudder complex (PRC). Despite this, there is little information in the scientific, technical, and regulatory literature on the issue of protecting the PRC from the effects of ice. The article considers a new constructive anti-ice protection of the PRC in combination with a variable profile rudder, protected by two patents for inventions. With the use of the SolidWorks software product, a calculated comparative assessment of the hydrodynamic characteristics of an ordinary rudder and a variable profile rudder in combination with anti-ice protection has been performed. The effectiveness of the steering gear of an ice navigation ship equipped with the proposed anti-ice protection using a variable profile rudder has been confirmed.

The article presents the main results of the scientific research work aimed at analyzing the possibility and computational justification of an alternative design solution for a berth-connected reinforced concrete storage vessel for oil products. The design is made in accordance with the requirements of resolutions MEPC.110(49) and MEPC.311(73) taking into account the special aspects of operation. The vessel is designed without a double bottom and double sides, which does not meet the requirements of 19.3.1 and 19.3.6 of MARPOL 73/78 Annex 1. The justification of alternative design solution safety has been made by calculation of the pollution prevention index. Such index is determined on the basis of oil spill parameters in the event of a side and bottom damage of the vessel hull in accordance with resolution MEPC.110(49). Additionally, calculations of the hull strength in a relatively mild collision have been carried out, together with assessment of the occurrence probability of such incident. Based on the above, a risk assessment have been carried out and decisions on the safety of an alternative vessel design solution for the assigned operation purposes have been made.

One of the promising technologies for repairing hull structures is the application of three-layer panels (sandwich panels). This technology was first applied on a ship with RS class in 2018. The article contains the main results of research work aimed at introducing this technology into RS regulatory framework. A review of the existing types of three-layer panels has shown that steel three-layer panels with solid homogeneous aggregate (STP) are the most popular and practical, but not yet regulated by the RS Rules. Analysis of the requirements of a number of classification societies for the certification of STP materials and the assessment of the strength of structures repaired with their use has resulted in the proposals for adjusting the current RS normative documents.

The article considers hydromechanical model of cargo-ballast operations of a tanker is considered, including the process of stripping tanks in accordance with the requirements of Ballast Water Management Convention of 2004. The model takes into account ship trim, stability, strength of the hull, physical properties of the pumped cargo and ballast; the shape and dimensions of the tanks, as well as the bottom set, including the location and shape of the ducts; topology and characteristics of pipelines, parameters of local resistances; characteristics of pumping equipment, capacity, pressure, permissible suction height, method of regulating the capacity; operating conditions, the scheme of cargo-ballast operations, the number of simultaneously operating pumps and their conditions of operation, the temperature of the pumped cargo and the method of stripping of containers.

The article provides comparative analysis of the requirements of classification societies, industry standards and standards of foreign shipyards for permissible technological parameters characterizing the change in the shape of the pipe at bending. Comparison of the requirements of industry standards for bending with the values of allowance for thinning as a result of bending in strength calculations shows a significant discrepancy in the requirements of regulatory documents. Based on the analysis, it has been concluded that it is necessary to harmonize the requirements for the allowable values of pipe wall thinning and develop the Register requirements for the allowable values of ovality and the size of corrugations after pipe bending.