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Precis File
SHIP NAME: Onomichi Maru KEY: NUM. ENTRIES: 4
source Japan FSA
type A
volume
material
dead 0
link

Nos 1 and 2 holds flooded. Broke in two and subsequently sank.


source Bishop et al, Naval Architect, 1985, pE141, March
type A
volume
material
dead 4
link

The 66,874 t displacement, 15 year old bulk carrier Onomichi Maru was one of several large ships lost in the North Pacific during the 1980-1981 winter; while she was proceeding at 5.25 knots, carrying coal from America to Japan in approximately Beaufort 8 conditions, her forecastle suddenly bent up through about 5 degrees, oscillated for about 2 hours, and then dropped off; the rest of the ship, about 85 pct of its length, sank 40 days later. A paper published as a result of the Japanese government enquiry into the loss appears to be the only attempt to explain any of these 1980-81 losses; it offered the explanation that the loss could have been due to the combination of an unusual wave, large heaving and pitching, slamming and other factors. The present authors discuss this explanation, and suggest that there may be a simpler and more fundamental answer: that the vessel suffered massive fatigue because of narrow band resonance. This hypothesis, resulting from a study at Brunel University, is presented in some detail; it is stressed that it is a hypothesis and not an assertion, and may be relevent to other losses.

If the authors' hypothesis is thought wrong, any objections to it should be properly presented; it is a matter that should not be dropped.


source HOOKE
type A
volume
material
dead 0
link

While on a voyage from Mobile to Sakaide, carrying a cargo of 53,000 tons of coal, the Japanese motor bulk carrier Onomichi Maru broke in two between No 1 and No 2 hatches after huge cracks appeared in her hull during very heavy weather conditions about 800 miles SE of Nojima Saki in lat 31.00N, long 156.10E, on December 30, 1980. The forward section sank two hours later but the aft section drifted away; however, the crew of 20 was rescued by the Japanese motor ore carrier Dampier Maru, which landed them at Kashima.

The aft section subsequently sank east of Guam on February 11.


source CTX
type D
volume
material
dead 0
link

In the FSS, the Japanese study is called: Japan (1981) MOT of Japan, Technical Study relating to the accident [sic] on Onomichi Maru (in Japanese), 1981. The CTX has reviewed neither paper.

The Japanese FSA summary is uninformative, almost misleading. Yet the FSA authors must have been privy to the same information as Bishop et al. In fact, they reference the Japanese study.

Using Bishops displacement and FSA's dwt, the ship's lightweight would be 10,533.

Beaufort 8 is not particularly bad weather, Needless to say, despite Bishop et al's plea, the matter has been dropped,