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Preparedness frees you to enjoy the night passage, guided by wind, sea,
stars, and moon.Up ahead, you see a bridge with three white lights and red and green lights. What
does this tell you? How comfortable are you entering an unfamiliar harbor at
night with multiple channels and blinking lights? What steps would you take to
make this transit safe and easy?
In Th is Chapter, You’ll Learn How To:
D Instantly identify the four bridge types and what their lights mean
D Transit any harbor or channel at night in four easy steps
D Solve the riddle of the invisible lighted range
D Find a danger bearing to clear a deadly reef—without plotting!
Cracking the Mystery of Bridge Lighting
The U.S. Coast Guard Bridge Administration Division regulates bridge con-
struction and lighting. Nevertheless, most bridges present an array of lights
confusing even to the saltiest mariner. You need to find the center span to
allow the greatest clearance for your sailboat mast or powerboat antennas.
Understanding the various light signals indicating closed or open is essential
to avoid catastrophe. The following definitions for bridge terms may help.
Low steel. Th e lowest part of the bridge superstructure. A chart shows the
clearance at mean high water to the bottom of the bridge span, called low steel.
Clearance gauges. Vertical white boards, called clearance or tide gauges,
have blue or black numbers showing the height to the low steel. Th ey are
installed to the right of the bridge entrance on each side. Newer gauges
show an electronic display.
Abutment. Th e supports on either end of the bridge.
BRIDGES, NIGHT
PASSAGES, AND
OTHER TRICKY
NAVIGATION
SITUATIONS
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