Author(s): Takamune Kitazawa; Robert Ettema
Linked Author(s): Robert Ettema
Keywords: No Keywords
Abstract: A three-meter long, model hull of a tanker ship with simplified bow shapes was towed through a simulated brash ice channel in the model-ice towing tank of the Iowa Institute of Hydraulic Research (IIHR). The study was directed to investigate resistance forces encountered by commercial ships, with hulls characterized by a long parallel part, transitting brash ice channels. The model hull was structurally divided into a bow portion and an aft portion, which were coupled and instrumented so that resistance forces exerted on the bow as well as the total towing force could be measured. Two bow forms were used; a wedge bow and a simplified icebreaker bow. From the results of the experiments it is shown that resistance to hull motion through brash ice may consist of the following components: bow resistance due to internal friction and accumulation of brash ice; bow resistance due to submergence of brash ice; bow resistance due to momentum exchange between hull and brash ice; parallel-part resistance due to friction between hull and brash ice; stern thrust due to ascension of brash ice at the hull's stern; and open-water resistance. The ratio of each component to the total resistance depends on bow shape, hull speed, brash-ice characteristics and channel dimensions.