2.1 Basic Plan
The objective of this research project was to develop an icebreaking cargo vessel that could navigate the deep outer waters of the NSR between Japan and Europe without stopping at ports along the way. Critical to the design of this ship is its ability to compete economically with other sea routes, such as the Suez Canal route. First, to decide which ship types to focus research on, container ships and bulk carriers were studied, with an eye on the current state of cargo shipping between East Asia and Europe and future trends. Container ships, it was determined, are likely to attract the greatest increase in demand in the field of logistics, but their key advantages of fast and regular navigation suggest that they offer no advantage to the NSR over other sea routes. Bulk carriers, on the other hand, do not suffer as great a loss in speed in ice-covered waters as container ships do, and the demand for the cargo in general was expected to be relatively high. For these reasons the bulk carrier was chosen as the target ship type.
Because the ship was intended for navigation of the deep waters of the NSR, the restrictions on draft encountered in the work on coastal NSR vessels were less severe. Therefore, to improve the competitiveness of the NSR ship in comparison with the ships plying the Suez Canal route, the deep-draft NSR ship was designed to have the largest displacement possible for the expected route. In addition to having ship icebreaking capability equivalent to the shallow-draft NSR vessel developed in the Phase I, the excellent performance in open water was considered to be vital in shortening the total voyage-days. The main features required for the new vessel with deep draft are as follows.
* Main dimensions: In consideration of the shallowest section of the intended route, the Sanikov Strait, the ship's draft (d) was set at 12.5m. The width of the ship (B) was set at 30m, the broadest possible given the width of the escorting icebreaker. Based on these values and correlation data between the main dimensions of icebreaking cargo ships in service, the length between perpendiculars was set at 8B and the ratio D/d, where the depth, D, was placed in the range of 1.4-1.5.
* Hull form: Based on the results of Phase I, hull form D-d was selected as the design base, as this hull form represented a favorable balance between the performance in ice and in open water. The greater length-width ratio of the deep draft ship than the shallow-draft models was realized by lengthening the parallel body. The block coefficient of the ship was to be in the range 0.75-0.77.
* Ship structure: A double-hull structure of the ice class IA Super was selected.
* Displacement, deadweight: Given the dimensions, kind of ship and features of the aft body selected above, the ship's displacement was estimated at 71,000t. Given the ice-strengthened and double-hull structure of the ship, its light weight was estimated at 20,000t and its deadweight was planned at 51,000t. This deadweight will fall in an extension of those of existing ships (Figure B-16).
* Icebreaking performance: The ship is expected to be capable of continuous icebreaking at 3 knots in ice 1.2m thick.
* Sea speed in calm water: Taking account of speed loss in ice-covered water, the sea speed in calm water was set at 17 knots, in order to exceed the number of voyages between Hamburg and Yokohama via the Suez Canal using the current Panamax bulk carriers.