avoiding collision by eye or radar 139
globe. Below are some guidelines for making E.A.S.A. solutions part of your
defense against collisions.
- Determine the situation (meeting, crossing, or overtaking).
- Determine the risk of collision (by drift bearings or vessel lighting).
- Put an E.A.S.A. solution into play.
Meeting a Stationary Vessel
Imagine that you are approaching a vessel at anchor, dead ahead at a range of a
quarter mile. Your boat speed is 3 knots. You must take action within 5 minutes
to avoid collision (60 ÷ 3 = 20 minutes to travel 1 mile; 20 ÷ 4 = 5 minutes to
travel^1 / 4 mile).
E.A.S.A. solution: Slow to bare steerageway and change course, aiming
well astern of the vessel. Stop if necessary.
Meeting a Moving Vessel
Relative speed increases when two
vessels are traveling toward one
another from opposite directions.
Determine bearing drift. A constant
bearing indicates a high risk of colli-
sion. At nighttime, take action if you
sight both red and green sidelights
on a vessel. On larger vessels farther
away, you may see two white masthead
lights before you see the sidelights. If
the masthead lights line up like a pair
of range lights, this indicates that you
are on a collision course.
E.A.S.A. solution: Change
course 90 degrees to the right. Shoot
drift bearings until you are clear.
Crossing Another Vessel
Determine bearing drift. Use sector-
ing (described earlier) to determine
which vessel should stand on and
which should give way. Another
method to use during daytime is to
picture the nighttime sidelight color
of a crossing vessel. If the vessel
crosses from left to right, you’d see
Small Vessel Basic
Navigation Lights 101
Navigation Rule 23, Lights and Shapes,
Power-driven Vessels Underway,
and Navigation Rule 25, Lights and
Shapes, Sailing Vessels Underway,
describe the light patterns. Study the
two illustrations with the captions:
“Power-driven vessel underway—less
than 50 meters” and “Sailing vessel
underway. Same for Inland.” Compare
the similarities on both vessels. Notice
that both vessels carry sidelights: red
on the port side and green on the
starboard side. Both vessels also carry
a white sternlight. But only the vessel
under power carries an additional
white light, called a masthead light,
above the sidelights and sternlight.
If a sailing vessel turns on its engine,
it becomes a power vessel and must
switch on its white masthead light.
Navigation lights show over a part of
a circle called an arc. This prevents
one light from blotting out another.
To learn more about arcs on vessel
lights, see Rule 21.