166-RR-1
Page 1 of 1
©
Copyright Lapware 2002
USCG 166 Book 1
STEPS
You are on a vessel heading due north and see the lights shown one point on
your port bow. This vessel could be heading __________.
Possible heading is determined in the following manner:
See illustration: DIAGRAM 51
HEADING 000° - 11.25 ° = N x W (348.75°)
Green Side Light bearing N x W (348.75°)
Compute the reciprocal of the observed
bearing and then move 10 points (112.5°)
to the LEFT or in a counter-clockwise
direction.
Step No. 1 - Reverse the bearing
N x W (348.75°) ± 180° = S x E (168.75°)
Step No. 2 - Move 10 points to the left
168.75°
S x E
- 112.50°
-10 points left
056.25°
NE x E
Possible headings are:
NE x E (056.25°) to S x E (168.75°)
(A) SE
Southeast (135°) = ANSWER
(B) NE
(C) SW
(D) NW
RULES OF THE ROAD
VESSEL HEADING
E
W
N
GREEN
Side
Light
RED
Side
Light
NxW
SxE
NExE
SE
Green Sector
Visible
S