INVESTIGATION

CASE 13
When Steel Meets Granite
Narrative
During its normal daily service, a ro-ro ferry
was approaching harbour at its full sea speed
of about 20kts via a particularly narrow
channel (Figure 1). It was mid-afternoon, the
weather was fine, sea calm, visibility good and
it was low water on a spring tide. The unusual
tidal conditions in the area meant that there
was about 3kts of tidal stream setting the
ship off course to port even though it was low
water.
The master was very familiar with the route
and was using the visual leading transit marks
for the harbour approach as the primary means
of positional awareness. The chief officer was
also on the bridge as well as the OOW and a
helmsman, who was steering by hand.
The ship was fitted with an ECDIS system
and the crew were certified for ‘paperless’
navigation. The ECDIS safety contour had
not been adjusted for the local conditions
and, although the cross-track distance (XTD)
settings were appropriate, the audible alarm
had been switched off.
As the ferry proceeded down the channel,
the master observed visually that it was
slightly to port of the intended track and
made a succession of 2° heading alterations
to starboard; however, these adjustments
were insufficient to regain track and the ferry
raked over a charted, rocky pinnacle. A heavy,
shuddering vibration was felt throughout the
ship as the outer hull was damaged along most
of its length (Figure 2). The
hull was breached in several
places but the subsequent
flooding was contained in
the double-bottom void
spaces.
Figure 1: Chart showing the vessel’s intended and actual tracks
MAIB Safety Digest 1/2017
27