Methodology and algorithm for determination of permissible speeds at a ship's vertical side crash against the ice field edge

Abstract

The article discusses the main provisions of the methodology and the algorithm for determining the permissible speeds when a vertical ship's hull side impacts the edge of the ice cover, taking into account the possible breakage of the ice cover of small thickness from the buckling. The cases of ship hull interaction with ice that require solving the problem of determining permissible speeds in this formulation have been identified. The principal calculation dependencies allowing to determine the maximum contact pressure and linear load, as well as the maximum contact force, have been presented. A procedure of transition from structural strength to ice strength, which can be implemented by means of MS Excel, without involving specialized software, has also been proposed. The solution of this problem is shown as applied to merchant ships having low ice class, bulbous bow and vertical sides in the area of the waterline entrance for transverse and longitudinal framing of sides. It is assumed that the permissible speeds are determined only by the structural strength of the side stiffeners — main and intermediate frames in case of transverse framing and longitudinals in case of longitudinal framing. The results of investigation presented in the article are intended for inclusion in the new methodological recommendations of the Russian Maritime Register of Shipping (RS) for the development of safety certificates for ice-going ships.