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Precis File
SHIP NAME: Diamond Grace KEY: NUM. ENTRIES: 7
source LMIU
type D
volume Y
material
dead
link

Grounded on reef in Tokyo Bay in 35 21.7 N 139 43.2 E 02 Jul 1997 Refloated with tug assistance within an hour and anchored Bottom plating damaged, two tanks ruptured Large oil spill Ar Yokohama 07 Jul and sd 10 Jul Ar Singapore 01 Aug. Repairs effected at Singapore Sailed 08 Sep.


source IOPCF
type D
volume 1500T
material
dead
link


source ERC
type D
volume 441000G
material
dead
link


source OILDROP
type D
volume 1550KL
material
dead 0
link http://www.epa.gov/oilspill/pdfs/oildrop1.pdf

Oil Drop, October 1997 says 1S and 3S punctured, oill leaked into No 2 ballast. If so, this was an "automatic" transfer, which reduced spillage considerably. Puts time at 1005 AM, cargo at 257,000 tons,

The tanker's captain reported that the ship ran aground when it tried to pass between two fishing boats by slowing down. The tanker was then carried by tide and gusts. The report said the tanker suffered a strong shock immediately after it started running at dead slow.


source LINK
type A
volume
material
dead
link http://www.geocities.com/TheTropics/Shore/7006/97dec.htm

Japan's Yokohama Local Marine Accidents Inquiry Agency on 25 Dec ordered that the pilot who was aboard the Diamond Grace be suspended for one month. Seigi Ushio, 57, was aboard the ship when it went aground in Tokyo Bay on 2 July. The agency said that the grounding was the result of Ushio not ordering a proper course. It also said that no action willbe taken against the master, Hidenori Tsumematsu, 55, although his action of not asking the pilot to take an appropriate course should be criticized. The report recommended that the large volume of traffic in the bay be mitigated through better training of pilots, among other things. The Dimaond Grace spilled 9,750 barrels of crude oil after damaging its cargo tanks off Yokohama's Hommoku Pier. The tanker made a starboard turn to avoid a fishing vessel.


source Shigyo, T, Japanese Spill Experience, in Oil Spills Prevention, Preparadness and Respose Workshop, Dec 10-12 1998, Almaty, Kazakhstan
type D
volume 1550L
material
dead
link

The grounding resulted in three gashes on the hull of the Diamond Grace: one at the bottom of No 1 Starboard, and each one at the bottom of the transverse bulkhead between the No 1 and No 2 starboard tanks, and between the No 2 and No 3 starboard tanks.
This author is listed as the spill response team commander. He says initial estimate of the spill of 15 million liters (which is still being repeated by some sources) was off by a factor of ten because oil from 1S and 3S drained into the empty segregated ballast tank, 2S.

This indeed happened, but his report shows no understanding of hydrostatic balance. It includes a sketch in which the final level in the three tanks are all at the external waterline. And even if a portion of the oil had not drained into 2S the initial estimate would have been off by a factor of five. Presumably his paper was vetted by his staff and others. Looks like nobody involved understood hydrostatic balance.


source CTX
type D
volume 1550KL
material
dead
link

Several sources says "pilot error in dealing with 2 fishing vessels,

UK Telegraph says "calm seas and clear weather" but also says "hits Nakanose coral reef". Coral doesn't grow this far north. Puts spill at 13000T.

Ships was a MARPOL single hull built just 3 years earlier.. Here is a case where the protectively located segregated ballast really worked, but not in the way the proponents of this "anti-collision" measure claimed but in the way that the proponents of the various systems for transfer of cargo away from damaged tanks claimed. The real value of double sides is not in collisions but in a grounding where they will automatically collect oil in the same manner. But in the IMO system for calculating outflows this capability is ignored.

Of course, this ship is a modern VLCC with only 14 very tall cargo tanks plus two slops. A pre-Marpol single hull of this size would have about 24 shorter tanks. The interesting question is would a pre-marpol ship with smaller, shorter tanks have spilled more or less. To answer this question we need the exact location of the damage.

The lack of understanding of the physics of hydrostatic balance on the part of the response team is dismaying. You would think that this is the first thing they would be taught.

As to cause, CTX has not read the Yokohama Inquiry Report, which to our knowledge has not been translated; but, reading between the lines, it sounds like pilot was placed in a real dilemma. If he doesn't slow down, he runs down the fishing vessels. If he slows down, he loses steerageway and drifts aground. If this were the case, twin screw would probably have prevented this spill.

CTX needs a lot more information on this very interesting casualty. CTX needs somebody who can translate the Japanese investigation reports.