Page 104 - Collision Avoidance Rules Guide

Section II - Conduct of Vessels in Sight of
One Another

RULE 11
Application
Rules in this Section apply to vessels in sight of one another.

COMMENT:
Rule 3(k) states that vessels shall be deemed to be in sight of one
another only when one can be observed visually from the other. The
Rules in Section I1 do not apply to a vessel which has detected
another vessel by radar, and has established that risk of collision
exists, if the other vessel cannot be sighted visually. Rule 19 of
Section I11 applies only to vessels navigating in or near an area of
restricted visibility which are not in visual sight of one another. In
restricted visibility, therefore, vessels may initially have to comply
with Rule 19 of Section 111 then subsequently have to comply with
the Rules of Section I1 when they come into visual sight of one
another. A vessel is unlikely to be excused for not complying with the
appropriate Rule of Section TI if it is considered that failure to sight
the other vessel was due to a bad visual look-out.
It is conceivable that instantaneous sighting may not occur, even if
both vessels are keeping an efficient visual look-out, due to such
factors as different intensities of navigation lights or to patches of
low fog obscuring the bridge of one vessel but not her masthead
lights. A vessel must comply with the Rule which relates to the
situation which applies at the particular instant.
In the discussions which took place before the 1972 Conference
serious consideration was given to the possibility of formulating one
set of manceuvring rules which would apply in all conditions of
visibility. The Conference decided against adopting this principle,
however, mainly because it is usually possible for vessels to sight one
another in sufficient time to recognise the lights or shapes being
displayed so that the degree of responsibility can be based on the
vessel’s ability. to take effective avoiding action.

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