SRI, NKK and MHI conducted four kinds of model tests in ice: resistance test in level ice, self-propulsion test in level ice, turning test in level ice and resistance test in a ridge. The details of each test are described below.
* Resistance test in level ice
This test is the most basic test of ship performance in ice. As Table B-1 shows, the ship is expected to be able to maintain a speed of 3 knots while performing continuous icebreaking in ice 1.2m thick. Focusing on these requirements, the test conditions were set as in Table B-3. Under the stipulated conditions, a ship model was towed in level ice, and the resistance and motions of the ship were measured. Before the model test, mechanical properties of the model ice, such as its Young modulus and flexural strength, were measured as well.
* Self-propulsion test in level ice
The self-propulsion test in level ice was conducted under the same test conditions as the resistance test. Under the stipulated conditions, the ship model was made to run under its own power, and thrust, torque and number of revolutions of propeller as well as the motions of the model were measured. Before the model test, mechanical properties of model ice were measured.
* Turning test in level ice
The turning ability of the model was tested in level ice of 33.3mm thick (proportionate to 1.2m in full-scale). The turning tests were carried out at the rudder angles of 15°and 30°.
* Resistance test in a ridge
The highly active ice movement in the coastal seas of the Russian Arctic accompanies a deformation process of sea ice. The presence of ridges is a great hindrance to the navigation of ships. A variety of ice ridges were therefore simulated in the tank tests as well, and the model resistance was measured as it passed through them.
Model tests in open water were also carried out. These tests included a self-propulsion test in calm water, manoeuvering test and seakeeping test in waves. Each test is described below.
* Self-propulsion test in calm water
The self-propulsion tests were conducted at a range of speeds from 0.5m/s to 1.7m/s. This range includes the speed 1.37m/s, which is equivalent to 16 knots in full scale. Bow type A was combined with both stern types and both propeller types, and the model tests were carried out in the four combinations A-a(CP), A-a(NP), A-b(CP) and A-b(NP).
* Maneuvering test in calm water
To evaluate the manoeubrability, a turning test, reverse spiral test and zigzag test were conducted with models consisting of the combinations of all three bows with stern a and an ordinary propeller: A-a(CP), B-a(CP) and C-a(CP).
* Seakeeping test in waves
The self-propulsion tests were carried out in regular head waves. To evaluate the effect of bow type on thrust increase and spray generation at the bow, the models had stern a and the ordinary propeller combined with each bow type in three combinations: A-a(CP), B-a(CP) and C-a(CP).
