Page 44 - Collision Avoidance Rules Guide

(iv) at night the presence of background light such as from
shore lights or from back scatter of her own lights;
(v) the state of wind, sea and current, and the proximity of
navigational hazards;
(vi) the draught in relation to the available depth of water.

(b) Additionally, by vesseb with operational radar:
(i) the characteristics, efficiency and limitations of the
radar equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather
and other sources of interference;
(iv) the possibility that small vessels, ice and other floating
objects, may not be detected by radar at an adequate
range;
(v) the number, location and movement of vessels detected
by radar;
(vi) the more exact assessment of the visibility that may be
possible when radar is used to determine the range of
vessels or other objects in the vicinity.

COMMENT:
This is an entirely new Rule which is of particular importance.
Rule 16(a) of the 1960 Regulations required every vessel to go at a
moderate speed in restricted visibility but there were no requirements
relating to speed in clear visibility. The need for a Rule relating to
speed in all conditions of visibility became apparent as a result of the
increase in the number of large vessels which sometimes carry their
way for a considerable distance after being stopped, and for which
shallow water effects may have a particular application.
The wording of Rule 6 and its location with respect to the other
Rules should leave no doubt that the setting of a safe speed is a
prerequisite in all conditions of visibility. It is, of course, in restricted
visibility that the need to moderate the speed generally applies and
the state of visibility is listed first among the factors to be taken
into account in determining a safe speed. Unlimited visibility should
not, however, be considered as justifying full speed under all
circumstances.
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