User's Manual Part 1
2
INTRODUCTION
NAVTEX is a method of transmitting navigational warnings and weather forecasts
from designated coast radio stations. All English language transmissions are made
on 518 kHz. Each station is allocated several time ‘slots’ during the day, when it is
permitted to transmit; these are normally at four hourly intervals. The only
exceptions to this are gale warnings and search and rescue messages, which may
be transmitted at any time.
Reception of NAVTEX is normally limited to an area of 200 - 300 miles radius
around each transmitting station, although considerably greater ranges are possible
at night.
Subject to IMO approval, additional local language transmissions may be made on
490 kHz and on 4209.5 kHz.
The NAV-7 has been designed to the latest European and International
specifications to provide up to date weather and marine safety information to
commercial vessels. It meets IMO requirements under GMDSS and is designed for
simplicity of operation. It will display reliable information day after day within
designated NAVTEX coverage areas.
Installation is straightforward. Connect the NAV-7 to a 12 or 24 volt DC supply and
connect a suitable antenna. Switch it on, and it will start displaying and storing
NAVTEX messages without further manual intervention. Note that if there are only a
couple of NAVTEX stations within range it may be several hours before the first
message is received.
If you are within an area where you are able to receive from many NAVTEX stations
(particularly at night), the NAV-7 may overwhelm you with information. It can
therefore be set up to display only those stations and message categories you want
to receive and which are applicable to the area in which you are sailing.
Normally, routine messages are repeated at four hourly intervals. Provided that the
NAV-7 is left running, repeated messages are not displayed more than once. Each
message is retained for three days (72 hours) after its last reception before being
automatically deleted, unless the message has been marked as locked.
Permanent installation of the NAV-7 can be made with either the bulkhead-
mounting bracket or the flush panel mounting kit provided.