2.2 Tank Tests and their Evaluation
A single model was used for all tests. Built at a scale of 1:43.64, the length between perpendiculars of the model was 5.5m. Three kinds of tests were conducted in level ice: resistance test, self-propulsion test and resistance test in a ridge. In calm-water, resistance test, self-propulsion test, overload test, turning test and self-propulsion test in waves were all carried out. For each test the approach was essentially the same as that followed in Phase I. All tests were conducted by NKK except the test in a ridge and seakeeping test, which were entrusted to SRI.
The results of the resistance test in level ice are shown in Figure B-18. For comparative purposes, the results for ship D-d in Phase I are added in the figure for comparison. Although the two models had almost the same resistance in level ice, a slightly higher resistance of the present model is attributed to the increase in frictional resistance of the lengthened parallel body and resistance increment caused by deep submergence of broken ice fragments by the deeper draft. The frequency of interactions between ice fragments and the propeller was examined in the self-propulsion test (Figure B-19). In comparison with ship D-d in Phase I, the deep-draft ship had a lower frequency of interactions. The longer parallel body of the deep-draft ship could probably make it easier to clear out the ice fragments in the propeller disk. The thrust deduction coefficient and wake factor are plotted in Figure B-20. The relationships among horsepower, speed and ice thickness in the tests in level ice are illustrated in Figure B-21.