Methodological recommendations for justification of allowable conditions for operating of ships in ice

The article discusses new methodological recommendations that provide the possibility of developing Safety Certificates for ice-going ships. The considered recommendations are partially presented in the existing RS regulatory documents for solving similar problems. This article pays attention to clarifications of existing recommendations and gives a more detailed description of the newly developed ones. Clarified recommendations for determining the physical and mechanical characteristics of ice for calculating ice movability and ice strength have been given. Practical methods for calculating the ice propulsion of a ship in various ice conditions (on its own in solid and broken ice, in a channel behind an icebreaker) and a method for determining the achievable speeds of a ship at different percentages of power utilization of the propulsion system are proposed have been proposed. Some provisions of the methodology for assessing the safe distances of a ship in a channel behind an icebreaker at different ice thickness and concentration have been clarified, including those for ships equipped with azimuthing propulsion systems. The main provisions of the methodology for solving problems of ice strength calculation — determining permissible and dangerous speeds of a ship's movement in ice, based on a hydrodynamic model of the interaction of the ship's hull with ice, have been outlined. A method for determining permissible and dangerous speeds for ships with bulbous hulls and vertical side in the area of the hull bow has been proposed. The features of determining permissible speeds of movement in the freezing waters of the port of ships with a low ice class have also been indicated. A method for estimating the ultimate ice thickness that a ship's hull can withstand during ice compression has been proposed based on a probabilistic-deterministic approach to calculate loads during ice compression.

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