MODEL AND FULL-SCALE TESTS WITH AN INNOVATIVE ICEBREAKER BOW

The traditional icebreaker bow form is a compromise between level icebreaking capability, performance in other ice conditions, and hydrodynamic behavior. The uncompromised need for capability to break thick level ice recently resulted in applications of both rounded and box-shaped bow forms for use on Siberian rivers. To investigate the potential of such non-shipshaped designs, a project was initiated at WARC in 1984. From this research, a successful combination of round bow and plow was selected for further testing in full scale. An experimental bow of 300 tons displacement was constructed and suspended from a 2000-kW icebreaking salvage tug by means of eight force transducers producing full data in the X-Y-Z planes. The model test results correlated with extraordinarily elaborate full-scale tests. Significant results included an increase in icebreaking capacity from 0.5 to 0.9 m and propulsion free from ice interaction. First-year ridges were forced without difficulty and the turning radius was the same as for conventional forms and smaller than those obtained for box-shaped bows. Conclusions are drawn as to the advantgages and drawbacks of the new bow form, which is not intended for universal use on icebreaking ships.