Page 56 - Collision Avoidance Rules Guide

Banshee-Kildare

Now at what period of time is it that the Regulations begin to apply to two
ships? It cannot be said that they are applicable however far off the ships
may be. Nobody could seriously contend that if two ships are six miles apart
the Regulations for Preventing Collisions are applicable to them. They only
apply at a time, when, if either of them does anything contrary to the
Regulations, it will cause danger of collision. None of the Regulations apply
unless that period of time has arrived. It follows that anything done before
the time arrives at which the Regulations apply is immaterial, because any-
thing done before that time cannot produce risk of collision within the
meaning of the Regulations. (Lord Esher, 1887)
The above case was heard in the last century when ships were rel-
atively slow. The two vessels concerned were involved in an overtak-
ing situation in Dublin Bay, their speeds being respectively 6 and
7 knots. The distance at which risk of collision begins to apply might
well be considered to be greater than 6 miles between vessels
approaching one another at high speeds, in the open sea, on recipro-
cal or nearly reciprocal courses. The distance must depend very much
on circumstances and particularly on the speed of approach. In rivers
and harbours where vessels frequently have to change course risk of
collision may only be considered to apply at relatively short distances.
All available means

The requirement to use all available means appropriate is also
included in Rule 5, but for a different purpose. In determining
whether risk of collision exists with a vessel which has been visually
sighted the taking of compass bearings may be especially important.
In clear visibility in the open sea the use of radar and associated
equipment is more likely to be considered necessary for determining
risk of collision, with a vessel seen to be approaching, than for the
purpose of keeping a general look-out. The radiotelephone may be
used to advantage in certain circumstances for the purpose of clari-
fying a situation involving two vessels and indicating intentions, in
addition to its use for determining information about the location and
movement of other vessels as an aid to the keeping of a proper look-
out. When using a traffic separation scheme, information received by
VHF radiocommunication concerning the movement of other vessels,
particularly about vessels moving against the established direction of
traffic flow, may give early indication of impending risk of collision.
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