Racons The Canadian Aids
Some aids to navigation are enhanced by
To Navigation System
the use of Racons (which is short for RAdar
Canada uses the same IALA Region B sys-
beaCONS). Racons, when triggered by pulses
tem used in the United States in a combined
from your vessel’s radar, transmit a coded
lateral and cardinal system. The shape, color
reply to your radar that appears in the form
and light characteristics all indicate the func-
of a series of dots and dashes identifying the
tion of the aid to navigation. In general, the
Racon. For more information, see page 850.
“red right returning” rule applies, which
Radar Reflectors
means that red markers, nuns, buoys or oth-
er navigation aids are left to starboard when
Many aids to navigation incorporate spe-
returning into a harbor from a bay, or into
cial fixtures that enhance the reflection of
any inlet or body of water from the open sea.
radar energy. These radar reflectors help
In addition, the system of cardinal marks
radar-equipped vessels to detect buoys and
indicates nearby obstructions or hazards. The
beacons. They do not, however, positively
shape of the topmark indicates the direction
identify a radar target as an aid to navigation.
of the hazard or obstruction relative to the
buoy. See the illustration on page 294.
Canada also has special-purpose buoys that
are usually similar to U.S. buoys designed for
the same purpose. Daymarks include red tri-
angles and green squares somewhat similar to
marks used in the U.S. Intracoastal Waterway.
NAVCEN Services
Mariners have Web and phone access to the
NAVCEN watch-standers are available 24
U.S. Coast Guard’s Navigation Information
hours a day to handle inquiries (703-313-
Center (NAVCEN) in Alexandria, Virginia,
5900). Specifically for GPS users, a 24-hour
CEN/GPS
which provides user information and status
voice recording (703-313-5907) provides ac-
A
V
reports for Loran-C, GPS, DGPS, marine
cess to a 90-second message of current GPS
N
radio-beacon and general radio-navigation,
status. NAVCEN is online at www.navcen.
as well as access to weekly editions of the
uscg.gov.
various local notices to mariners issued by
NAVCEN safety and radio-navigation mes-
individual Coast Guard districts.
sages may also be heard through U.S. Coast
ion
NAVCEN cannot assist with problems us-
Guard broadcast stations on VHF-FM chan-
at
ing GPS receivers. Consult your owner’s
nel 22A and HF-SSB 2670 kHz .
manual or contact the manufacturer for
receiver-related difficulty.
a
v
ig
N
Global Positioning System (GPS)
Differential GPS
locations, they can calculate the exact time
For most navigational situations, 100-
it should take to receive the signals and
meter accuracy is more than adequate.
compare that with the actual time of receipt,
However, in tight quarters, particularly with
thereby determining the error. The DGPS
limited visibility, mariners require greater
stations relay this error information to GPS
degrees of accuracy. To achieve this for civil-
sets nearby on short-range frequencies.
ian users—without compromising military
Although many GPS units are marketed as
objectives—a system known as Differential
being “DGPS-enabled,” a separate antenna
GPS (DGPS) was developed. Local DGPS
and receiver connected to the GPS unit is
stations—often located at radio-beacon
required to receive the differential signal and
sites—receive the signals from GPS satel-
transfer it to the GPS.
lites. Because these stations are at precise
843