Global Maritime Distress and Safety System
Whenever a ship is under way, it is necessary to receive information
concerning any hazards in the area that the ship may be operating.
Broadcast warnings fulfill this requirement. In recent years a system has
been established that notifies mariners by radio messages. All messages
are broken down into two categories. The first category is called
Hydros. Hydrolants cover warnings in the Atlantic Ocean, Hydropacs
cover the Pacific Ocean. The second category is called Navareas, which
covers specific areas. Navareas contain information that advises
mariners of operating area warnings. An example would be a navigation
aid adrift. Refer to section III of the NTM for more information.
Broadcast warning message boards must be updated from the weekly
To meet changing requirements and to provide better service using the
latest technology, DMAHTC has worked with the Navy to provide
up-to-date warning information. Thus the NAVTEX part of
NAVINFONET (fig. 1-19) system has evolved and is currently going into
place on all fleet units.
Figure 1-19. Components of GMDSS (from Pub 117).
NAXTEX will completely replace the Hydros and Navareas warnings
sometime in the future. Refer to the NAVTEX receiver instruction
manual for complete information.