Page 152 - Collision Avoidance Rules Guide

A change of speed is generally more effective as a means of avoiding
a close quarters situation with a vessel approaching from near the
beam. In a meeting situation a reduction of speed is unlikely to have
an appreciable effect on the distance of closest approach but it could
be considered to be ‘avoiding action’ as it reduces the closing speed
and gives more time for assessment and further action by both
vessels (Rule 8(e)).

19(e) Where risk of collision does not exist
Determination of risk of collision is required by Rule 19(d) and by
Rule 7. A series of radar ranges and bearings, together with a plot or
equivalent systematic observation, indicating that it is safe to proceed
will usually be necessary to justify continuing at a speed greater than
bare steerage-way. The possibility that a fog signal may be heard
from a different vessel to the one whose echo has been observed must
also be taken into account. The direction and distance of sound signals
can be misleading in fog. In the Oakmore-Aras, 1907, Sir Gore11
Barnes put the following question to the Elder Brethren:
Were the indications such as to show her master, distinctly and unequivo-
cally, that if both vessels continued to do what they appeared to be doing,
they would pass clear without risk of collision?
If it has been determined that risk of collision does not exist a vessel
is not required to reduce her speed to the minimum at which she can
be kept on her course when a close quarters situation is developing,
or on hearing a fog signal forward of her beam. This may apply, for
instance, when crossing astern of a vessel being overtaken or when
vessels proceeding in opposite directions on their correct sides of a
narrow channel pass close enough to hear each other’s fog signals.
A ship’s whistle can sometimes be heard at long distances.

Fog signal apparently forward of the beam
Although the Rule refers only to fog signals heard apparently
forward of the beam it may be prudent to reduce speed if a signal
appears to come from near or slightly abaft the beam. The direction
of sound signals cannot be relied upon. It was held in one case
(Bremen-British Grenadier, 193 1) that a vessel should have stopped
her engines, on the grounds of good seamanship, when several
signals were heard just abaft the beam on the same bearing.
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