25,000 DWT Icebreaking Bulk/Container Carrier
This 25,000DWT ship was designed to keep the same icebreaking capability as 40,000DWT ship with 9m draft limitation, and aimed to be deployed in the Southerly route and regional routes. The configuration and carges are similar to 40,000DWT ship. Icebreaking capabilities are interpolated from the results of 40;000DWT. Figure 2.4.3 shows the general arrangement and rough body plan. Lpp is approximately 2m shorter and D is 1m smaller than those of 40,000DWT in order to maintain cargo capacity requirement and hull girder strength.
50,000 DWT Icebreaking Bulk Carrier
The design studies were performed in the Ship and Ocean Foundation as the relevant project of the INSROP to improve capabilities of the vessel employed in the NSR, especially economical viewpoints. Before this vessel was developed, the extensive studies were carried out to select an optimum bow and stern form for 8m draft ship, 25,620 ton in displacement(kitagawa,H.,1995). As first step, three typical bow and two stern forms were selected to grasp basic performance, and Figure 2.4.4 shows their configuration. Bow form A so-called“conventional”,represents relatively simple V type frame lines, large flare angles, and stem angle close to 25°. Bow form B“Spoon”represents close to spoon‐bow form,large frare angle of bow at water line, and stem angle of 19°. Bow form C“Concave”has concave frame line of bow at the load water line, constant large flare angle from bow to shoulder. As for stern forms, Stern form“a”has U‐shape frame lines, mariner type stern profile, and Stern form“b”has U-shape frame line accentuated near the bottom.
The extensive series test both in ice tanks and open water tank were performed including maneuvering tests in ice tank and sea keeping tests in wave. Then,the new bow form named Bow form D was derived as an optimum bow form incorporating the advantages of Bow form A that was superior in open water performance as well as the advantages of Bow form B that exhibited less ice resistance. As for stern form, a new stern form“d”was proposed, that has shorten parallel portion and smaller inclination angles at frame lines from SS.1/2 to 3 in order to improve maneuvering performance. The bow and stern form developed for this 8m-draft vessel extended to 12.5m draft vessel with approximately 50,000 DWT. The performance of newly designed ship was confirmed by also extensive ice and open water tank tests. Figure 2.4.5 shows the general arrangement and body plan and principal particulars. The vessel has 7 holds, navigates 17 knots in open water and breaks 1.2m level ice at 3 knots.
