As a result of its research on nonlinear finite element analysis of side structures subject to ice loads, ABS has issued a new set of comprehensive Guidance Notes on Ice Class. The Notes provide direct calculation procedures for designing ice strengthened vessels by addressing three principal elements in ice strengthening design: alternative side structures, minimum propulsion power requirements and strength of the propeller. These are considered the key factors in determining the ability of a vessel to operate safely in ice infested waters.
In 2003 ABS published detailed procedures for evaluating alternative structural designs using nonlinear finite element method (FEM). This was in response to the issuance of interim guidelines from the Finnish Maritime Administration (FMA) regarding direct calculations for longitudinally framed hull structures. The just published Notes are an extension of that work and offer alternative methods for the determination of minimum propulsion power requirements and procedures for propeller strength assessment based on FEM, which is a new approach to the analysis applicable to ice class vessels. The Notes include guidance for ice propulsion analysis, with supporting model and full-scale test data, ice load definitions and stress analysis of ship structures due to ice loads. These direct calculation methodologies help to identify the more balanced structural arrangements and propeller blade strength criteria to meet the most stringent ice class requirements. The Notes supplement ABS ice class requirements contained within the ABS Steel Vessel Rules.