Seamanship_Secrets_185_Tips_-_Techniques_for_Better_Navigation-_Cruise_Planning-_and_Boat_Handling_Under_Power_or_Sail_(Re)_e..

bridges, night passages, and other tricky navigation situations 129

Red Sectors Give Instant Danger Bearings

Some lights have lenses divided into white and red sections, called sectors.
The red sector covers a region of extraordinary danger to mariners; the white
sector marks deep, safe water. Red sectors never flash, but show a steady, fixed
red light. White sectors show one of the four common characteristics: flash-
ing, quick flashing, occulting (a flash in which the duration of light exceeds
the duration of darkness), or isophase (a flash in which the light and dark
intervals are of equal duration).
Cartographers plot the red sector as an arc between two dotted lines
(see chart illustration), radiating from the position dot of the light. Th e Remarks
column in the Light List shows the bearing of each line (in degrees true) as
observed from your vessel.

Name & Location Position Characteristic Height Range Structure Remarks

REBECCA SHOAL

LIGHT

24 34 42 N

82 35 06 W

Fl W 6s

(R sector)^66

W9

R 6

Square

skeleton tower

on brown

pile foundation.

Red from

254 ° to 302°

Th e Light List information for Rebecca Shoal Light. Th e Remarks column shows the true
bearing to each red sector dotted line as observed from your boat.

Th e chart showing Rebecca Shoal Light. Notice the red sector danger bearing and note
that the shoals in the immediate vicinity of Rebecca Shoal are not marked by the red
sector. It’s up to the mariner to determine safe passing distance to keep his vessel clear of
these dangers.