A literature study of existing methods for estimating the resistance of ships in ice is presented and a review of the influence of several ship particulars on the level ice resistance is made. The applicability of the Lindqvist method to vessels with conventional bow shapes is assessed, pointing out the strengths and weaknesses of the formulation. The concept of an improved method based on weighting factors is presented. Finally, recommendations for a model test campaign with an instrumented model are given in order to acquire sufficient knowledge to develop a revised method.
For typical icebreaker shaped vessels with an inclined bow and low flare angles the major components of the hull-ice interaction process are quite well understood. Analytical methods exist to predict the average resistance based on few inputs for the hull shape characteristic and ice properties. For non-typical icebreaking ships the interaction process includes many unknown phenomena like cracking, splitting and crushing, which are difficult to be described by straight forward approaches. Furthermore, the accumulation and clearing of the broken ice floes is completely different. Finally, the database (e.g. from model tests) of performance records for such vessels in solid ice is very limited.
The demand for a more profound understanding of ice interaction with non-icebreaker shaped vessels results from an increasing number of those ships accessing Arctic and Antarctic waters. Examples are cruise expedition vessels and government vessels with multiple missions (coast guard, rescue and salvage). Even if the sailing time of those vessels in ice is limited to few weeks in a year, a detailed assessment of their capabilities in ice is required to optimize their design and operational profile.
A study is proposed to investigate and understand the basic process of sea-ice interaction with ships of open-water or moderate icebreaking shape. The objective of the study is to identify the major process phenomena and to find correlations between parameters, especially those between the hull geometry, ice properties and motion characteristic of a vessel. The study is supported by the Office of Naval Research (ONR) and includes theoretic investigation and physical model tests conducted in the large ice model basin at the Hamburg Ship Model Basin (HSVA). The aims are as follows:
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improve principal understanding of the hull-ice interaction process, ice failure and the components contributing to the ice resistance
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find methods to evaluate the ice performance (ice resistance, attainable speed) as well as the factors of major influence
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enhance quantity and quality of ship-ice interaction observations
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provide a database of results obtained under controlled conditions