The following information pertains to a liquid petroleum gas tanker (LPG)
which has a similar construction to an LNG tanker.
The information was obtained from a Japanese marine registry record.
The annotations [[text]] were added by the authors for clarity.
The Motorship “Yuyo Maru No. 10” (gross tonnage of 43,723),
laden with 20,831 MT of light naphtha,
20,202 MT of propane and 6,443 MT of butane,
left Ras Tanura, in the Kingdom of Saudi Arabia, for Kawasaki,
and the port of Keihin on October 22, 1974.
While the vessel was sailing northward
along the Naka-no Se Traffic Route in Tokyo Bay on November 9,
she collided with the Motorship “Pacific Ares” (gross tonnage of 10,874),
manned with a Taiwanese Master and 28 crew members,
laden with 14,835 MT of steel products,
en route from Kisarazu for Los Angeles, USA.
The collision occurred about 13:37 hours on the same day
slightly northward of the boundary line of the Naka-no Se Traffic Route.
As a result of the collision, the “Yuyo Maru No. 10”
suffered a large hole at the point of collision,
with her cargo naphtha [[CH-IV: The naphtha was carried in its
outer ballast tank (between the insulated
LPG tanks and the hull of the ship).
The LPG cargo tank was not penetrated.]]
instantly igniting into flames.
As a result of the outflow of naphtha overboard,
the sea surface on her starboard side
literally turned into a sea of fire.
The “Pacific Ares” showered with fire burst into flames in the
forecastle and on the bridge.
While explosions occurred one after another
[[CH-IV: naphtha, not propane]]
[CTX: believes LPG heated up, vented, and was involved in the fire],
attempts were made to tow the “Yuyo Maru No 10”, outside the bay,
but she ran aground in the vicinity of Daini Kaiho.
She was successfully towed out of Tokyo Bay
and sunk south of Nojima Saki on the afternoon of
November 27 by cannon, air bomb and torpedo attacks
staged by the Maritime Self-Defense Force.
On board the “Yuyo Maru No. 10”,
five crew members were killed
and seven others injured by this accident.
The “Pacific Ares”, whose forward section
was completely crushed and superstructures burned down,
was later repaired.
Her crew members were all killed except one
person, who was injured but rescued.