Page 74 - Collision Avoidance Rules Guide

When a vessel is obliged to take action to avoid collision with
another vessel which is crossing, or which she is overtaking, she may
be prevented from making course alterations due to lack of sea room
or to the presence of other vessels; in such circumstances it will be nec-
essary to slacken speed or take all way off. In restricted visibility when
a close quarters situation cannot be avoided with a vessel forward of
the beam, or a fog signal is heard forward of the beam, it will usually
be necessary to reduce speed or stop the ship (see pages 133-5).
The speed must also be reduced if it is necessary to allow more
time to assess the situation. Rule 5 requires that a full appraisal of the
situation and of the risk of collision should be made. When a vessel
is sighted at short range and it is not possible to determine how she
is heading due to poor visibility or weak lights the best action for a
ship with a good stopping power may be to make a drastic reduction
of speed. In the Buccleuch-Kyanite 1905, the Kyanite altered course
away from the danger when the loom of a sailing vessel was seen fine
on the bow. Lord Low said:
But at that time . . . [the officer in charge of the Kyanite] did not know that
the Buccleuch was a crossing ship. He had no idea in what direction she was
sailing. All that he knew was that a ship under sail was in dangerously close
proximity. In such circumstances, I think that his duty was to stop and
reverse. That was the one course which, I think, he could not have been
wrong in following. What he did do was fatal, if, as it turned out, the
Buccleuch was a crossing ship.

Officers aboard modern power-driven vessels are usually reluctant
to use the engines when it becomes necessary to keep out of the way
of another vessel in the open sea. If the engines are not controlled
from the bridge there is likely to be an appreciable delay before tele-
graph orders are put into effect unless the engines are on stand-by.
Even if there is an immediate response a large vessel moving at high
speed carries considerable momentum and cannot be expected to
rapidly lose her way. If the engines are stopped on a tanker of over
200,000 tons deadweight it may take more than 20 minutes before
the speed is halved and over an hour before the vessel comes to rest.
These times can be considerably reduced by putting the engines
astern as soon as possible but there is usually a delay of several
minutes before the astern power becomes effective.
A drastic reduction of speed will be less readily apparent to another
vessel than a substantial alteration of course, whether observed
55