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The Masthead
March 2012 Page 14
June 2012 Page 14
Post-Capsize Safety Lessons
in 1987. When consulted by a deck
officer who is knowledgeable in their
use, these curves show when the
margin of safety is being eroded and,
therefore, when mitigating action—
such as shortening sail or altering
course—is required.
Two-point call for action
So what happened on
The Master handed over the controls
at 12:00 to the officer of the watch
(OOW) with a shortened sail plan that
was “good to 40 knots” and instruc-
tions to bear off if the wind increased.
The vessel was on a broad reach and
making about 5.5 knots in 15- to 20-
knot winds. The Master's standing
orders required that he be called if
the vessel was at risk. There was no
discussion of the squall curves at the
handover. This is key. In fact, the
OOW, who was appropriately certifi-
cated for his position, was not aware
they were on board, did not consult them, and was not trained in
their use.
Had the stability book been consulted, it would have shown that,
in order to provide a margin of safety in typical gusting condi-
tions, the heel angle should be limited to 24 degrees. Instead, as
the squall approached, the angle of heel increased from around
10 degrees to about 23 degrees in wind speeds of about 23
knots. At this point, the margin of safety may have just been
sufficient for a gust, but certainly was not sufficient for the en-
counter with the squall when it came. The OOW, not perceiving
the risk to the vessel, was not concerned. But the heel angle then
quickly increased and, within a very short time,
was on
its beam-ends with the deckhouses flooded. The OOW's attempt
to change course was too late.
Ultimately, no single factor caused this accident. Rather, it was a
combination of the inherent limits of
; a lack of knowl-
edge of these limits on the part of the OOW; the associated lack
of awareness of the developing risks; and, consequently, the
absence of mitigating action to reduce sail, change course, or
secure the vessel watertight.
As a result of its investigation, the Board made two recommen-
dations, which—if adopted—should help ensure that a similar
accident does not occur in the future. In essence, every sail-
training vessel should have the necessary information onboard
to define its individual vulnerability to specific weather condi-
tions; and its deck officers should be trained to use that informa-
*This range of estimated wind speeds takes into account uncer-
tainties with the value of sail heel force coefficient, which may
also be thought of as the "efficiency'' of the sails.
Jonathan Seymour FICS, MNI, was a Member of the Transporta-
tion Safety Board of Canada from 1999 until he retired from the
Board in 2011.
This article originally appeared in
Ship & Boat International
, March/
April 2012, published by the Royal
Institution of Naval Architects (RINA).
It is reprinted with permission.
To read the complete Transportation
Safety Board (TSB) of Canada report
on the
capsize —
Investigation Report M10F003,
Diagram 4 - Squalls associated with thunderstorms can contain some
downdraft element that reaches the ocean surface.
Diagram 3