Many designs that seem fanciful at first glance, such as the DAS model above, spring from technologies for testing models in ice tanks. The ice tank is an experimental facility used to test a ship's performance under simulated ice conditions. Resources were discovered on the seabed of the Alaskan and Canadian Arctic Ocean in the late 1960s, which prompted dozens of these tanks to be built in the 1970s and 1980s around the world. In general, an ice tank is a towing tank placed in a refrigerated housing; the refrigeration system forms an ice cover in the tank by cooling the room in the insulated housing. In Figure 4.1-16, an overview of a model test in an ice tank is shown. Most such tanks are long and narrow, used mainly for testing forward motion as in ordinary towing tanks. In Finland, however, a wider tank is also constructed to allow testing of maneuverability.
(2) Research & development of the hull forms for the future NSR vessels
At the SOF, a Research Committee for the NSR was established in tandem with the start of INSROP; at the same time, the SOF established a project, named JANSROP, to develop future NSR vessels and to bring a uniquely Japanese perspective to NSR research in the advancement of the INSROP project, with particular emphasis on the technological aspects of the NSR. Divided into a Phase 1 (1993-1995) and a Phase 2 (1996-1997), JANSROP performed research into icebreaking ships for navigation of shallow, coastal waters in Phase 1 and into vessels with deeper drafts in Phase 2. Through this research program, useful data and information were fully utilized from past R&D projects for icebreaking oil tankers, funded by the Nippon Foundation. Here we see an example of the development of hull forms for icebreaking ships from Phase 1.
The 50,000DWT bulk carrier ("50BC"), as described in the later Section 4.4, is the vessel with deep draft developed in Phase 2, one of the ships tested under the NSR operation simulation project. The research was conducted according to the following study flow.
・Basic design (1993)
Natural conditions along the coastal routes, ports and harbors were surveyed and principal particulars of the candidate vessels were determined. The candidate ships were designed and the ship models were constructed.
・Tank testing (1994)
Using the ship models constructed in the previous year, various model tests were carried out in ordinary towing tanks as well as ice tanks.
・Development and testing of new hull forms (1994, 1995)
The hull form and the models' performance in ice and open water were analyzed through the model test data, which led to the design of new hull forms. The model tests were carried out on the new hull form.
・Overall evaluation (1995)
Overall evaluation of each hull form was carried out with sufficient references to the model test results and a final design was proposed.
