Author(s): Graham K. Holder; John E. Carter; Andrew L. Hart
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Abstract: Tests were carried out in a towing tank to determine the Flow and Impact Pattern of Ice Pieces under Ice Breaking Ships with a view to developing bottom strengthening criteria. The results showed that while the distance travelled by an ice piece along the bottom of the vessel increased with increasing vessel speed, the underkeel clearance did not have any significant effect. Tests carried out with various sizes of ice blocks showed that an ice dune formed under the forward part of the hull, the length of which was directly related to the ice piece dimensions and Ship speed. At a speed of approximately seven (7) knots in all cases the dune was wiped off in open water (when no ice was fed to the dune). The results led to the conclusion that bottom damage to vessels in ice covered waters may, in some cases, be due to grounding on the ice dune when the vessel transits from deep to shallow water. Application of the results, together with an analysis ofprototype ice dimensions, resulted in recommendations for bottom strengthening in ice transitting vessels.
Year: 1994