Chapter
MARITIME SAFETY INFORMATION
ONE OFTHE MAIN ADVANTAGES OFTHE GMDSS is the ability, where service
has been provided, to receive Maritime Safety Information (MSI
including weather, navigation and Search and Rescue (SAR) information)- automatically, and with a paper printout. The two primary GMDSS
services that cater for this function are:
The NAVTEX service, an international service for broadcasting coastal
weather and navigation information, and initial distress messages.
The Inmarsat SafetyNET service, for broadcasting MSI for ocean
waters and, in some countries which do not have a NAVTEX service,
for broadcasting coastal information.
Many countries still use the traditional methods of broadcasting
MSI, by voice on marine VHF and MF IHF SSB Radio, or by radio-
telex (Narrow Band Direct Printing - NBDP) services on Marine MFI
HF SSB Radio - either instead of NAVTEX/SafetyNET, or additional
to those services.
This chapter explains how to use ALRS Volume 3 (MSI) and ALRS
Volume 5 (GMDSS) to identify automatic (NAVTEX and SafetyNET)
services, and alternative/supplementary (VHF ISSB) services.
Using SafetyNET
The SafetyNET service is provided as part of the Inmarsat-C
'Enhanced Group Call' (EGC) service. EGC provides a method of
broadcasting information to a number of vessels at the same time, without
any need for the vessels to respond.
The most common way to receive SafetyNET information is
through an Inmarsat-C receiver. To receive this information, you must
'log-in' (Chapter 8) to the satellite that broadcasts the information you
require, for the area you require.
For the purposes of broadcasting MSI, the world is divided into
16 international 'NAVAREAS', or 'METAREAS' (The prOViders ofnavigational information use the 'NAVAREA' term; weatherl
meteorological services prefer 'METAREA').
ALRS Vol. 5 (SafetyNET section) includes a world map showing
the 16 NAV/METAREAS (I to XVI - see figure 2.1). The map also
shows the 'footprint' of each of the four Inmarsat satellites (AOR-EI
12 THE NAUTICAL INSTITUTE