ņ3 
5.1.1    Collision Avoidance 
 
 
Problems of Collision Avoidance in Navigation 
 
Marine  collision  avoidance  is  one  of  the  problems  that  have  been  recognized  from  of  old.  Now,  it  will  be 
described briefly who the collision avoidance is positioned among the navigational aid problems. 
The navigation pattern of all mobile craft constitutes a system with some closed loops regardless of the media 
through which the mobile craft travels, whether air, water, the boundary between air and water, or space. This 
pattern consists of two closed loops in principle, one of which is a collision with another mobile craft and the 
other  is  a  loop  of  finding  a  right  and  safe  way  to  reach  a  predeterminate  destination.  Fig.  5-1  shows  the 
conceptual diagram of  navigation pattern by  MR.  E.W. Anderson. The  closed  loop  of  collision avoidance is 
shown on the left side and the closed loop of finding a right course on the right side. 
 
 
 
Destination
Mancuver
Cource and 
speed
Course
Ship traveling in controlled condition
Insrument or 
judgement
Control
 loop
Compass 
and log
Caluculati
on
Fixing by radio wave, 
visual and celestial 
observation
Judgement
Visual and radio 
watch
Traffic rule
Cllision
avoidance loop
Vessels Spacing loop
Collision avoidance Decision of cource
Guide loop
Dead 
reckoning
 
 
 
Fig. 5-1    Navigation Pattern 
 
 
 
Marine Accidents and Collisions 
 
Among marine accidents, collision accidents have been highlighted as the tonnages and speeds of ships become 
higher along with the increase in traffic at sea. If a tanker carrying dangerous articles such as crude oil collides 
with any other vessel, then not only the vessels involved with the accident but other vessels in the vicinity, port 
facilities, inhabitants in the coastal area as well as marine resources may also suffer immeasurable damages and 
troubles. Collision accidents have a high percentage of the marine accidents that have occurred in recent years. 
To  cope  with  these  problems,  any  effective  measures  are  needed  and  some  equipment  to  achieve  collision 
avoidance requirements have been developed at rapid strides.