Current data indicate that abnormal waves of great steepness and height are quite common in the World Ocean. The assessment showed that the probability of a vessel encountering such waves can be quite high. The impact of abnormal waves on sea vessels poses a significant danger to them, since the possibility of a vessel encountering them is not taken into account when de-signing. This article considers two scenarios of a vessel’s interaction with an abnormal wave. In the first case, the vessel first hits its trough and then buries into the top (the vessel passes through a “hole” in the sea), while in the second case, it is the other way around. The vessel dynamics are modeled using the mathematical apparatus developed by the author, including a modified system of equations for the vessel’s longitudinal roll, which allows taking into account the vessel’s be-havior in burrowing conditions. The case of the appearance of one wave of abnormal height, which stands out sharply against the background of the surrounding waves, is considered. The value of hydrodynamic impacts on the bow end during interaction with an abnormal wave is es-timated. The efficiency of the new bow end design developed by the author is analyzed. It is shown that during interaction with an abnormal wave, this technical solution allows to signifi-cantly reduce the value of hydrodynamic load and increase the safety of the vessel.

The relevance of this study is due to the critical dependence of the domestic marine engine industry on imported torsional vibration damping technologies, exacerbated by the cessation of supplies and maintenance of foreign spring and silicone dampers. The creation of domestic dampers is of particular importance in the light of the tasks of technological sovereignty of the Russian state. Comparative laboratory tests of spring and silicone dampers were carried out to quantify the effectiveness of damping torsional vibrations. A silicone damper and a prototype of a spring damper developed on the basis of the author's creation methodology using reverse engineering technology of a serial sample of a spring damper model D90/37 from Geislinger are being investigated. The criterion of effectiveness was a decrease in the amplitude of torsional vibrations, estimated by the magnitude of stresses in the shafts of the laboratory stand, depending on the frequency of forced vibrations and the frequency of rotation of the stand. It was found that in the range of stand rotation frequencies up to 250 min–1, the efficiency of the dampers is comparable (voltage reduction by 2.3-3.5 times for non-resonant and up to 9.7 times for resonant vibrations). At a frequency of over 250 min–1, the prototype spring damper is more efficient, reducing the voltage amplitudes by 1.8 times compared to 1.4 times for a silicone damper. The most dangerous defects were identified: for the prototype spring damper, the leaf springs were blocked, leading to a 4-fold increase in stresses; for the silicone one, the flywheel mass was blocked, causing a 2.8-fold increase in stresses. The obtained results can be used in the creation of domestic analogues of dampers and the development of a technique for non-selective diagnostics of their technical condition.

The analysis of soft-start systems of asynchronous motors used on ships is carried out. As a result of the literature analysis, the problem of reducing the quality of electricity in terms of harmonic distortion during operation of thyristor soft-start devices has been identified. It was also determined that the amplitude values of the overvoltage peaks in the general section of the cable network when using a soft starter are almost three times higher than the nominal value of the amplitude of the supply voltage. A simulation model of a soft-start device has been compiled, taking into account operation in power supply systems of limited capacity. The simulation results and their analysis showed the presence of odd harmonics in the network and a significant increase in the total coefficient of harmonic components of the current when starting an asynchronous motor using a soft starter. Thus, during the simulation, it was revealed that the use of soft-start devices in ship systems, along with a decrease in starting currents and voltage drops, negatively affects the quality of electricity. The obtained simulation results will allow for accurate calculation and rational adjustment of passive and active filters used on ships to ensure high quality of electricity.

The results of the design and construction of an experimental installation for studying transverse, torsional, axial and related vibrations of a ship's shaft line are presented. The analysis of publications devoted to the research of dynamic phenomena accompanying the operation of the propulsive complex is carried out. It is noted that in order to increase the accuracy of calculation methods and experimental data, the mechanical vibrations of the shafts must be considered as combinations, i.e., not isolated. The design of an experimental installation is described, the operation of which is close to the real operating conditions of the shaft pipeline. The general principles of experiments that can be carried out when using individual components of the device are given. The operation of the installation components determines the list and range of experimental factors. The results of work on assessing the operability of the constructed installation by sequentially switching on components and evaluating their effect on the stress-strain state of the shaft pipeline are presented. The vibration parameters were recorded by strain gauge measuring equipment mounted on the shaft surface. The measurement results are presented in the form of tensograms of transverse, torsional and axial vibrations of the shaft. The analysis of experimental data revealed the presence of separate zones of dynamic instability when the corresponding components of the installation are switched on. Boundaries are defined for each dynamic instability zone and normal and tangential mechanical stresses are estimated. The design of the installation makes it possible to increase the accuracy of studies of both individual types of vibrations of the ship's shaft line and their combinations by increasing the accuracy of simulating the operation of the shaft line in real operating conditions. The main area of scientific research that will be conducted on this device is devoted to solving theoretical and experimental problems of improving the reliability of marine power plants.

At the initial stages of design, performing a complete 3D analysis of the processes occurring in the elements of cooling systems of modern high-temperature engines can be either very costly in terms of computational processes, or even impossible due to the lack of necessary geometric 3D models at these design stages. But already at the initial stages of design, it is very important to determine the rational characteristics of the cooling systems of the elements of such engines as reliably as possible, since it is often on the basis of such assessments that the most important technical and economic decisions are made that determine the final characteristics of the designed facility. Correcting the consequences of incorrectly made decisions at this stage of design, if they are made, can be difficult and costly, and in some cases impossible. The relevance of using the criterion equations obtained by various authors to evaluate the necessary parameters is substantiated. The long-term practice of using such equations to perform an engineering analysis of cooling systems has confirmed both the high reliability of the results obtained and the relatively low labor costs of engineers to perform the work, which significantly reduces the iteration time required to make correct technical decisions and achieve optimal configuration of various cooled elements (housings, chamber parts combustion chambers, cooled blades, etc.) as soon as possible. A comparative analysis of the characteristics of the element of the cooling system of a turbomachine is performed using the criterion equations obtained by various authors. There is a fairly good agreement between the results of calculating the heat transfer coefficient when calculating using various criterion equations, and the possibility of using these criterion equations in practical calculations is considered. The necessity of developing a software module using optimization approaches to find rational parameters of cooling systems using jet methods of organizing the movement of cooling air is emphasized.

The analysis of soft-start systems of asynchronous motors used on ships is carried out. As a result of the literature analysis, the problem of reducing the quality of electricity in terms of harmonic distortion during operation of thyristor soft-start devices has been identified. It was also determined that the amplitude values of the overvoltage peaks in the general section of the cable network when using a soft starter are almost three times higher than the nominal value of the amplitude of the supply voltage. A simulation model of a soft-start device has been compiled, taking into account operation in power supply systems of limited capacity. The simulation results and their analysis showed the presence of odd harmonics in the network and a significant increase in the total coefficient of harmonic components of the current when starting an asynchronous motor using a soft starter. Thus, during the simulation, it was revealed that the use of soft-start devices in ship systems, along with a decrease in starting currents and voltage drops, negatively affects the quality of electricity. The obtained simulation results will allow for accurate calculation and rational adjustment of passive and active filters used on ships to ensure high quality of electricity.

The individual and total capacities of electric drives of fan installations have significant values, which requires monitoring their electrical energy consumption in nominal and start-up operating modes to prevent overloading of the ship's network, the occurrence of power exchange fluctuations between generators, and a decrease in the quality of electricity. High-quality operation of electric drives of fan installations on modern ships is carried out using frequency converters that allow smooth starts, stops and speed control. In the conducted experimental studies, an Optimus Drive AD80-4TD75 frequency converter is used to power an asynchronous fan electric motor, which includes an uncontrolled rectifier and an autonomous inverter. The oscillograms of voltage, current, and electric motor revolutions obtained in the start and braking modes using linear and S-shaped control laws show good results. The use of the S-shaped control law has some advantages over the application of the linear law, because transients are smoother and the electric drive operates more smoothly. The special capabilities of the Optimus Drive AD80-4TD75 frequency converter make it possible to maintain constant pressure and flow in the air duct when using feedback in the electric drive. It is proved that the application of the proportional frequency control law of the supply voltage does not ensure the maintenance of pressure and frequency when changing the position of the air dampers, while the introduction of a constant integration time when using the proportional integral control law ensures stable maintenance of the set values of pressure and flow over the entire range of changes in the position of the air dampers.

Container transportation is an integral part of international trade. Thanks to the standardization of containers and a well-developed logistics infrastructure, they ensure fast, reliable and cost-effective delivery of a variety of goods between countries and continents. Containerization helps optimize transport chains, reduce costs, and simplify customs procedures, making it a key element of the global economy. The cargo plan for a particular commercial vessel is fundamental from the point of view of safety, because its incorrect filling has the highest degree of impact on the safe transportation of goods. As the share of container traffic in the total cargo turnover is continuously increasing, the problem of shippers incorrectly declaring the actual weight of containers is becoming more urgent. Incorrect declaration of container weight may be due to the shipper's desire to save money on cargo transportation, as well as to an erroneous estimate of cargo weight, or to a failure to account for the weight of cargo containers, separation materials, etc. Overloaded containers or containers with incorrectly specified weights pose serious problems from the point of view of ensuring the safety of the transport vessel – they can lead to loss of stability of the vessel, increasing the risk of collapse of stacks, as well as transshipment equipment for container handling, creating danger during loading and unloading in ports and warehouses. If discrepancies in weight are found, containers can be detained at ports or returned to the shipper. The main causes and consequences of incorrect declaration of container weight are considered.

The concept of a modular container shipyard is proposed, designed to increase the mobility and economic efficiency of the production of unmanned boats, which is especially important in the context of the need for the rapid deployment of production facilities for the needs of ensuring the protection of the Russian Federation. An innovative approach to shipbuilding is proposed, based on the use of standard 20- and 40-foot containers, each of which has a strict specialized production or auxiliary function. The main advantages of a modular shipyard are considered, including mobility (the possibility of rapid deployment in various locations), scalability (adaptation of production capacities to changing needs), cost-effectiveness (reduction of capital and operational costs) and rapid deployment (reduction of commissioning time due to the stability of the shipyard). The applicable constraints, such as the shortage of qualified personnel and the difficulties of material and technical supply, are analyzed and ways to overcome them are identified. The basic configuration of the modular shipyard is presented, which includes an area for storage, material preparation, molding and lamination, hull assembly, electrical and mechanical installation, sensor installation, testing and fine-tuning, as well as administrative and management units. Preliminary technical and economic indicators (CAPEX and OPEX) for calculating a shipyard focused on the needs of the Ministry of Defense of the Russian Federation are presented, and the sensitivity of the main performance indicators to changes in cost and economic costs is analyzed, which leads to their leadership in the profitability of the project. The conclusion is formulated about the high investment attractiveness of the modular proposal in comparison with the capital construction of stationary shipyards, as well as about the significant potential for further development and taking into account this concept.

The main material in the construction of hull structures of ships is shipbuilding steel. In shipbuilding and ship repair, welding plays a key role in forming the joints of steel structures. Every vessel in the Russian Federation is undergoing an inspection. During the inspection, the technical condition and compliance of the vessel with safety requirements are checked. During the inspection of body elements, especially welded joints, defects are often found, characterized by a violation of the continuity of the weld metal, while their parameters go beyond the limits established by regulatory documents. If the permissible standards are exceeded, the defects must be removed according to the factory's technology, and the welds must be repaired. Repair of defective areas leads to an increase in repair time, as well as an increase in the labor intensity and cost of repairing or building the ship's hull. The question becomes relevant: to eliminate the found defect or to allow the construction to be operated. The technology of manufacturing samples for conducting experimental research is considered. The choice of material, dimensions and shape for the manufacture of samples, as well as the technological parameters of the manufacturing process, are justified. The method of obtaining internal defects in a welded joint is described. According to the results of radiographic control, welded samples with an internal defect were identified, as well as control samples without defects. An experimental fatigue testing facility has been designed and constructed, which makes it possible to reproduce the necessary conditions. In addition to the installation, a computer program has been developed that allows you to count the number of cycles before the sample is destroyed, as well as read the corresponding deflection of the welded joints.