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Accident Analysis
44
May 2013
The MOL-operated containership MOL
Comfort (Preevious name was APL Russia),
while under way from Singapore to Jeddah
on the Indian Ocean (12’30”N 60’E) at
about noon JST (07:00 local time) on June
17, 2013 during inclement weather, suffered
a crack amidships and ingressing water in
the hold. This made it impossible for the
vessel to continue on under its own power.
The MV MOL Comfort, an 8,000 TEU-
type 316 m. containership cracked in half
about 200 miles from the Yemeni coast at
about 12’30″N 60′E while enroute from
Singapore to Jeddah with a load of 7,041
TEUs. All 26 crew – made up 11 Russians,
1 Ukrainian and 14 Filipinos - escaped the
sinking ship on two life rafts and a lifeboat.
According to a report by IANS News,
the Indian Coast Guard in Mumbai diverted
three vessels in the area to assist. The MV
Yantian Express was first to arrive on scene
and rescued the survivors. The 2008-built
MOL Comfort sank a short time later, the
report said.
Weather at the time was strong winds and
seas up to six meters.
The ship’s operator, Mitsui O.S.K.
Lines, says that an Emergency Control
Headquarters has been established for the
incident and MOL is taking company-wide
measures to settle the matter. The MOL
statement said that damage was “extensive”
and that details of the incident were still
being confirmed.
A Catastrophic Structural Failure
From a naval architecture stand-
point, this is a puzzling situation. Ships are
designed to handle long period and large
waves that crest on the bow and stern and
have a trough amidships. This creates a sag-
ging situation that puts extreme tension on
the keel and compression at deck level. The
opposite, “hogging” situation occurs when
the crest of the wave moves to the center of
the ship and the trough of the waves are at
bow and stern.
The repeat flexing of the ship in these
perfectly timed waves is likely what caused
the loss of this vessel. In the photo above, a
perfect example of hogging is shown, where
the bow and the stern are both lying in the
troughs of two waves.
It should not have happened however.
Ships are built to handle this situation and
engineering rules are followed to ensure the
transverse “section modulus” of the vessel
is sufficient to handle these extreme stresses
imposed by nature. There are other possi-
bilities however…
The loading of the containers on boardmay
have exacerbated the situation. Although
the loading of the containers appears even
in the photo, the weight distribution of the
containers may not have been even. Had
heavier containers been loaded on the bow
and stern and lighter ones in the center of
the ship, the vessel may have been placed in
a hogging situation before she even set sail.
It’s speculation of course to say one way
or another, but assuming that she met class
requirements, it’s one possible explanation
for what happened.
Why and how did the MOL Comfort
break in half? The obvious answer is that no
one knows, yet. We will learn more follow-
ing an investigation, which is many months
in the future. In the mean time, what are the
likely causes of such a casualty? How and
why could an only five year old ship, deliv-
ered in 2008, built at good quality shipyard,
Nagasaki Shipyard & Engine Works, oper-
ated by a well known and established ship
owner, Mitsui O.S.K. Lines, simply break
in half?
The how is easier to answer right now
than the why. From the photographs imme-
diately after the ship began to crack, it
appears that the hull failed due to excessive
longitudinal bending stress. Container ships
typically operate with a certain amount of
bending stress due to the difference between
the downward load of the weight of the
cargo and the upward thrust of the buoyancy
of the water. The downward load is distrib-
uted more evenly along the length of the
container ship while the upward buoyancy
is more concentrated toward the middle of
the ship. Most container ships sail with a
moderate amount of hog, which is to say
with a slight downward droop in the bow
and stern due to the imbalanced load. This
is only noticeable when taking the draft of
MOL COMFORT
split in two
leaving
questions
behind...
Accidents