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Improving the designing quality of engineering systems and accuracy of their calculations is the basis for increasing the technical and economic indicators of modern engineering. Using automated calculations during the design phase raises labour productivity and product quality. There have been discussed the stages of software implementation of engineering calculations of the natural frequency of transverse vibrations of the ship propeller shafts. The problem of determining the first natural frequency of transverse vibrations of the shaft depending on the method of its fixing has been solved. A computational scheme has been build, which presents a uniform cross-section beam based on a point elastic support with a concentrated mass at its end. Differential equations for oscillations have been derived; the method of finding the natural frequencies has been described. For proper calculating natural frequency there has been developed a sequence and its software implementation in Maple environment with application of computer algebra package. The effect of the method of fixing on natural frequency of shaft transverse vibrations has been estimated. The problem of finding natural frequency of transverse vibrations on the extended elastic stern shaft bearing has been considered. The algorithm presented in the paper serves as a basis for formalizing and automating the stage of calculating transverse vibrations and is also applicable for calculating the natural frequencies of various elements, including the shaft and the sliding bearing.

The article analyzes the changes in requirements for oxide emissions resulted from fuel combustion in accordance with the International Convention for the Prevention of Pollution from Ships MARPOL 73/78. The problem of improving the energy efficiency of large-capacity gas tankers is studied by using different types of marine fuel. An energy audit was carried out on board a gas carrier with deadweight of 54,354 tons and propulsion system power of 12,400 kW. The energy audit relied on data of six voyages of a gas-carrier from July 14, 2016 to January 19, 2017. The Energy Efficiency Operational Index defined as carbon dioxide emissions per ton-mile of cargo movement, was used as a tool for assessing the energy efficiency of the ship. The research included the methods of comparative analysis of fuel change during the voyages. The comparative analysis was applied to calculate changes of consuming fuels with different lower caloric value. There have been given general characteristics of heavy fuel RMG 380 and diesel fuel DMA. Values of all parameters for analysis of operational coefficient of power efficiency were taken from the engineer’s log, cargo record book and oil record book, as well as from energy efficiency operation indicator reports of the company after each voyage. Based on the results of the assessment, the conclusions were drawn and perspectives were developed concerning the use of marine fuels and modification of the ship power plant. It has been inferred that using liquefied natural gas as main fuel increases power and economic efficiency of a ship and meets new requirements of MARPOL 73/78 to 2020 on sulfur content in fuel. The conducted research and preliminary calculations make it possible to predict an increase in the economic efficiency of a large-tonnage fleet while maintaining a high environmental friendliness.

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