Development of a design methodology for a hydrodynamic anchor in raft drift theory

The article develops an approach to designing an innovative means of reducing the wind-induced drift velocity of life rafts by using wave energy concentrated in the orbital motion of a raft on the wave profile. The relevance of the study is determined by the need to reduce the drift velocity of life-saving appliances, since this makes it possible to reduce the search area and increase the probability of rescuing people. The aim of the study is to develop a methodology for designing a hydrodynamic anchor in order to determine the parameters of the “raft–cable–hydrodynamic anchor” system that are sufficient to ensure a specified reduction in the drift velocity of a life-saving appliance under the worst conditions of the vessel’s navigation area. To achieve this aim, several interrelated tasks were solved in the course of the study, including obtaining and evaluating the results of studies of the hydrodynamic forces acting on the hydrodynamic anchor; analysing the effectiveness of the hydrodynamic anchor as a means of counteracting life raft drift; and developing methods for experimentally obtaining the operating parameters of the hydrodynamic anchor in relation to typical hydrometeorological drift conditions. The paper shows the relationship between the parameters of the “raft–cable–hydrodynamic anchor” system and presents a calculation of raft drift velocity for several wind speed values in the range from 6 to 20 m/s. For the purposes of designing a hydrodynamic anchor for specified drift conditions, the forces acting on the hydrodynamic anchor are presented in dimensionless form, taking into account the approximation of wave heights through wind speed according to the modern Beaufort scale. The proposed methodological model reflects an integrated approach to assessing the effectiveness of a hydrodynamic anchor in reducing raft drift. The use of a dimensionless coefficient and consideration of the true velocity of the hydrodynamic anchor through its projections demonstrated high efficiency in calculating cable tension in the life-saving appliance system. The proposed methodology reduces the required number of experiments. The results obtained make it possible to identify inconsistencies between related stages of hydrodynamic anchor operation and provide a scientific basis for improving the design of the hydrodynamic anchor and increasing its efficiency.

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