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CASE 1<br />
A Catastrophic Outcome<br />
Narrative<br />
A small, laden cement carrier capsized while<br />
on passage through a coastal channel that<br />
was notorious for its powerful tidal races and<br />
associated extreme sea conditions.<br />
As the vessel approached the channel, the<br />
weather deteriorated and gale force winds<br />
were opposing the strong tidal stream; this<br />
was creating treacherous conditions that were<br />
dangerous for small vessels. On entering<br />
the channel, it is evident from AIS evidence<br />
that the bridge team slowed the vessel down,<br />
almost certainly to reduce the risk of pounding<br />
or ploughing as they headed into the dreadful<br />
sea conditions (Figure 1). Due to the direction<br />
of the tidal stream, it is also evident that<br />
course alterations were required to maintain<br />
a safe navigational track over the ground.<br />
However, these course changes had the effect<br />
of placing the large sea increasingly on the<br />
vessel’s beam.<br />
When close to the area of worst sea conditions,<br />
the vessel capsized and remained afloat upside<br />
down for a considerable period of time; none<br />
of the crew survived. The alarm was not raised<br />
until about 25 hours later when the upturned<br />
hull was spotted by a passing ferry (Figure 2).<br />
The accident had gone unnoticed because: the<br />
capsize was so rapid that there was insufficient<br />
time for the crew to call a “Mayday”, the<br />
EPIRB almost certainly became trapped and<br />
did not float free, and the AIS transmissions<br />
ceasing was not observed ashore.<br />
The hazards presented by the tidal races were<br />
well publicised and the channel was impassable<br />
to small vessels during certain tidal conditions.<br />
The ship and its master had passed through the<br />
channel many times before and the master had<br />
previously taken action, normally by altering<br />
course, to avoid entering the channel at the<br />
dangerous times. About 3 months prior to the<br />
accident, the master had altered course across<br />
the sea in the approaches to the channel in<br />
order to avoid the extreme tidal races; however,<br />
this caused the vessel’s cement cargo to shift<br />
and resulted in a dangerous stability situation.<br />
Direction of wind and<br />
very heavy seas<br />
Direction of tidal stream<br />
Figure 1: Vessel's track showing headings through the water (vessel shown 10 times actual size)<br />
4<br />
MAIB Safety Digest 1/2017
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