avoiding collision by eye or radar 135
action you take crystal clear to the other vessel. Most collisions result from
confusion between vessels.
HOW TO CHANGE A DRIFT BEARING
A decreasing range along a steady bearing indicates that a risk of collision exists
between vessels. You must get that bearing moving to the left or right. Remember
that the action steps of changing course and/or changing speed are always available
to you.
In a crossing situation, slow or stop your boat. In a meeting or overtaking
situation, change course away from the other vessel. If needed, combine this with
a speed change.
Use Sectoring to Track a Crossing or Overtaking Vessel
In many crossing situations, you will see the other vessel’s red or green sidelight.
Treat that light as if it were a traffi c light. A red light warns you to stop or slow
down. A green light indicates that you are the stand-on vessel; the rules prescribe
that you should maintain your course and speed, and the onus to change course
or speed is on the other vessel. But there are times when you will be unable to
tell whether a vessel’s sidelight is red or green. It may very well look white! At
sea, red and green lenses decrease the range of a sidelight, or they might blend
in with the white deck lights used on larger vessels.
Use a fast and easy concept called “sectoring,” which works whether or not
you can distinguish the color of another vessel’s lights. Imagine dividing your
boat into four equal parts, or sectors. Split it down the centerline, and then split
it again across the middle (beam) of the boat. You now have four sectors: one
from the bow to the starboard beam; one from the starboard beam to the stern;
one from the stern to the port beam, and one from the port beam to the bow.
Th ose sectors remain in place no matter how the boat turns (see illustration).
Using sectoring to track a crossing or
overtaking vessel. As the boat turns, its
sectors turn with it.Sector colors: Our imaginary sectors will have colors similar to those used
in a traffi c light—red, yellow, and green. Your fi rst sector is red; the next two
sectors are yellow; and the fi nal one is green (see illustration). Remember, no
matter how you turn the boat, keep these sector colors in the same sequence.