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COLLISION AVOIDANCE
Necessity of Collision Avoidance ····························································
Disasters at sea, in particular collisions, have been highlighted as ship’s tonnage and speed as
well as ocean traffic increased.
A collision of a tanker carrying dangerous matter(s) such as crude oil against a ship brings
considerable damages to not only the tanker and the ship but also other ships traveling around,
port facilities, inhabitants along nearby coast, fishery resources, etc.
In recent years, the percentage of collisions to disasters at sea has greatly increased. To cope with
such situations, some measures to prevent ships from collision have been eagerly required and
various equipment have been developed.
Collision Avoidance Problems in Navigation··········································
To avoid collisions of ships has been recognized as one of navigational problems since early
times. This section briefly describes how collision avoidance is positioned among navigational
problems.
The navigation pattern of all vehicles is considered to be a system consisting of some closed
loops irrespective of the media through which vehicles pass, such as air, water, boundary of the
both and cosmic space. This pattern is considered in general to consist of two closed loops. One
loop is for avoidance of collision against other vehicles, and the other is for finding safe and
correct courses to predetermined destinations.
Fig. 1.8 shows the conceptual diagram of navigation pattern of E.W. Anderson. The closed loop
for collision avoidance is shown on the left side while the one for finding correct courses is
shown on the right side.
Destination
Course
Fixing by radio wave,
visual and celestial
observation
Traffic rule
Source, Speed
Visual and
radio watch
Compass and log
Instrument
or
Judgment
Maneuver
Judgment
Collision avoidance Decision of course
Guide loop
Dead
reckoning
Control
loop
Vessel’s spacing loop
Collision
avoidance loop
Calculation
Ship traveling in controlled condition
Fig. 1.8 Navigation Pattern
1.6
Concept of Collision Avoidance Measures
(Explanatory Notes)
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