The paper examines the regulatory framework of classification societies for the creation and operation of offshore fish farms, analyzes current articles on the problem of designing offshore fish farms in order to form a list of initial requirements for the design of offshore facilities of this type.

The purpose of the presented study was to collect and analyze the value of freight rates for the transportation of various bulk cargoes from ports of the Russian Federation in the period from April 2024 to April 2025 in accordance with the available up-to-date data. This work is of interest as a source of up-to-date information on the issue raised and allows us to form an objective assessment of the current situation on the market of freight rates in the ports of the Russian Federation.

In this article, an attempt is made to combine the results of a physical and digital experiment with CAD models in order to study the flight characteristics of a promising amphibious ekranoplan with an air cushion landing gear. 
The article provides a general description of free-flying and associated scale models of aircraft, a method for studying scale models is selected and a brief description of experimental work with ejection and radio-controlled models of an ekranoplan with an air cushion landing gear is given.
As part of the digital experiment, a 3D digital model of an ekranoplan was created and aerodynamic studies of this model were carried out in the CAD system. The obtained results of external visual flow around CAD models confirmed the rational choice of the aerohydrodynamic layout of the amphibious ekranoplan.

The rudders of variable profile, such as equipped with a flap and a pre-flap, have essentially higher efficiency than traditional rudders. Known designs of flap rudders have a few disadvantages, imperfections and impose constructive limitations on their technical characteristics. The article presents two new designs of rudders of variable profile, characterized by original actuators for controlling the moving elements of the rudder, as well as a device that improves the hydrodynamic characteristics of the rudder of variable profile. These technical solutions eliminate a significant part of the existing defects.

Specific indices are forming the basis allowing to consider ship’s behavior characteristics in complex seaworthiness verification and regulation system. In this regard the set of specific indices is to be wide enough. On the other hand, for future formulating of short-term seaworthiness indices characterizing ship’s behavior in a particular sea state on the basis of specific indices there is to be a possibility to consider the intensity of sea wave, ship’s speed and course angle. That possibility allows to perform short-term and long-term seaworthiness assessment. Peculiarities of firstand second-generation IMO stability criteria and connected research works are considered in the article. Criteria’s peculiarities allowing or not allowing to use them as specific seaworthiness indices are marked. It is concluded that using IMO second-generation stability criteria and ecological regulations in complex seaworthiness assessment and regulation is promising.

This paper presents a numerical (CFD) approach for determining roll damping coefficients of ship frame contours at an initial heel angle, modeling emergency scenarios. The method employs the strip theory hypothesis, solving Reynolds-Averaged Navier-Stokes (RANS) equations with the SST k-ω turbulence model and VOF method for free-surface tracking. Implemented in OpenFOAM using an Overset dynamic mesh, forced oscillations of two characteristic frame contours are simulated across a wide frequency range. Key results demonstrate good agreement between calculated dimensionless damping coefficients (μ'₄₄) and experimental data for upright (0°) positions. The findings validate the proposed CFD method's adequacy and practical applicability for accurately predicting ship motion hydrodynamic characteristics from inclined positions — crucial for stability and safety assessment in off-design conditions.

The relevance of the chosen research topic is explained by the active development of autonomous navigation and the need to solve tasks arising during the operation of marine autonomous surface ships. The mathematical model developed as a part of the research for the operational assessment of ship motion characteristics in irregular seas suggests a method for calculating the righting arm depending on the angle of roll and draft. In this paper, mathematical methods of surface approximation are considered, applicable for processing nonuniformly distributed data; approximations of the surface formed by a set of static stability diagrams corresponding to different cases of vessel mass loading are constructed, and the results obtained are compared. It is concluded that the methods based on cubic and biharmonic splines have the best approximation capabilities for this task.

Residual welding stresses that occur in the course of ship repair during the replacement of worn hull plates can pose a serious danger in terms of the overall longitudinal strength of the ship's hull. The paper analyzes the stress state along the contour of a rectangular sheet welded into the flooring taking into account the preliminary stretching of the flooring. Stresses are considered both in the weld material and in the near-seam zones of the flooring and the sheet being welded. A technological method is substantiated and formulated to eliminate the stress concentration on the contour of the welded sheet caused by the geometric parameters of the cutout while compensating for welding stresses by pre-stretching the repaired flooring.

The article outlines the main provisions of the methodology for accounting for the effect of icebreaker power capacity on the calculated ice loads. In the current RS Rules, this is implemented by adjusting the calculated intensity of the ice load on the bow area of the ice belt by introducing a correction factor, which is determined by a simplified formula depending on the ratio of the actual total power on the propeller shafts and the base power value. The correction factor is assumed to be constant within the ice class and independent of the displacement of the icebreaker. It is shown that when designing advanced icebreakers of high capacity, where the actual total power on the propeller shafts significantly exceeds the base value for the ice class, the approach proposed in the current requirements of the RS Rules may lead to an unjustified increase in the estimated intensity of the ice load. A methodology and algorithm for eliminating this disadvantage of the requirements of the Rules are proposed, based on the accounting of statistical information on the energy capacity of Russian icebreakers. It is shown that for individual projects with significantly increased energy capacity for their class, the transition to the developed recommendations solves the problem of excess calculated ice pressures.

An analysis of cylindrical specimens typesize influence on mechanical properties during uniaxial tension has been carried out for reliable estimation of high-strength shipbuilding 09CrNi2MoCu steel grade quality.
It is shown that selection of specimens typesize for tension test according to GOST 1497 has a determinant influence on quality estimation of highstrength steel due to heterogeneous structure forming in the quenching process after rolling of the plates with 24 and 30 mm in thickness.

For evaluation of applicability in marine constructions, the comparative friction tests have been carried out to determine the wear resistance of Magstrong H500 steel rolled plates and surfacing made with OZN-400M electrodes and welding solid wire. The structure has been studied and the hardness of the surface layers subjected to abrasion has been determined. It is shown that materials with similar hardness values have different wear resistance.

The article presents a concept of developing a digital twin (DT) of a ship at early design stages based on the principles of parameterization, integrity, direct design and modeling of ship operation in a transport system. Difference between such a model, intended for the conceptual design, and a digital twin of a product is described. The practical value of such a project-level DT is due to the possibility of its use as a tool for comprehensive project analysis of ice-going ships. Also, this approach has the potential to develop into a separate branch of ship design theory in the future. Based on the presented concept a project-level DT, a software tool was developed that covers four types of ice-going ships, such as the oil tankers, membrane-type LNG carriers, general-purpose dry cargo ships and cellular container ships. DT takes into account the characteristic features of the ice class: hull shape, presence of the double-acting concept, specifics of the light weight distribution and other factors. The article contains the results of a comprehensive verification of the developed DT, as well as the examples of its practical use during several research projects. Ideas for further methodological and technological development of the presented approach are also described in the article.

The possibility of using rotary regenerative heat exchangers in marine ventilation systems in order to increase the ship's energy efficiency is considered. A method for evaluating the efficiency of the system has been developed. Various design parameters of rotor are suggested. The calculation study of the effectiveness evaluation of all considered variants of the design of the rotor was conducted. Variants of optimization of the existing system of supply and outgoing ventilation with regenerative heat exchanger are obtained. The recommendations on the selection of parameters for rotor design are given.

The article considers the possibility of using cycloid gearboxes in high capacity marine power plants.
The work is a continuation of theoretical studies of cycloidal gears. The power ratios in the links and nodes of the K-H-V type cycloidal gear transmission are obtained.
For a visual assessment of the design and dimensions of the transmission, a sketch has been created in the Mathcad. The sketch of the transmission with the distribution of forces in the contacts of the elements, and the forces loading the bearing is given in the article.
A sketch layout of a cycloidal gearbox with a K-H-V transmission, designed for a power of 50 MW, has been completed. A comparison was made of the designs of cycloidal transmissions of the same power, with the same gear ratio and torque on the output shaft.