Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requires compliance with EEDI (energy efficiency design index) measures. For the container shipping industry this represents significant increases in fuel costs that can be mitigated above all by reduction of power demand, that is, of ship frictional resistance. In this respect, this paper discusses advantages attainable by application of the ACS (air cavity system) technology on the basis of recent KSRC (Krylov State Research Centre) studies. Savings in operating costs yielded by the enhanced propulsion performance for ships fitted with this system are illustrated by a case study of a containership.

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Object and purpose of research. The object of the research is a fundamentally new waterjet, intended for installation on ships of increased seakeeping performance with discrete-variable bottom deadrise. The purpose of the research is to develop and test three waterjet designs that can be installed on vessels with large deadrise, operating in severe weather conditions. Materials and methods. Experimental data of waterjet tests as a part of self-propelled models obtained in deep-water and cavitation test tanks of KSRC. Numerical simulation of the flow in water conduits of full-scale vessel taking into account the waterjet performance. Main results. As a result of the performed experimental and computational studies, the characteristics of three waterjet designs with partial-pressure water inlets were obtained: two waterjets with isolated single-elbow water ducts and inlets on the bottom section with medium deadrise, "II"design; two waterjets with combined water duct and inlets on the bottom section with maximum deadrise and double jet, “X” design; single waterjet with bifurcating two-elbow water duct and a pair of water inlets on the bottom section with maximum deadrise, “Y” design. Conclusion. The studies have shown that all the developed innovative waterjet designs are practically equal to conventional ones (or even better than them), and air suction creates a smooth, rather than a sharp force decrease on the impeller. The preference is given to a high-pressure water inlet with a bifurcated water inlet and a combined water conduit, because in intense waves, even if one of the inlets is aerated, the vessel will not abruptly lose speed or run off the course.

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Object and purpose of research. The objects of study are two containerships of 8100 and 8500 TEU capacities operated by Danaos Shipping Co. Ltd, Greece. The purpose is to experimentally verify alteration of bow shapes in the containerships designed to reduce hydrodynamic resistance at a lower operation speed, as well as to examine the impact of these alterations on energy efficiency design index (EEDI). Materials and methods. Experimental data from model tests were obtained in a deep-water test tank of Krylov State Research Centre. Main results. Based on the research studies the shaft power was determined versus the containership speed for the hulls with the original and modified bow shapes. Conclusion. Switchover to lower speeds combined with optimization and modernization of bow shapes will bring a possible reduction of shaft power and, accordingly, less fuel consumption and carbon dioxide emissions by about 40 %.