Time for a change...
Since the time of the Titanic, Marine
Radio has helped to save tens of thousands of lives, and become the
key element in Marine Search and Rescue (SAR).

Without radio, there can be no SAR...
Before the Global Maritime Distress and Safety System came into
force, marine radio equipment was required to provide operation over
a minimum specified range of 150 nautical miles.
This was based on the (not unreasonable) assumptions that ships
usually travelled well-used routes and that there were sufficient
ships at sea and shore stations dispersed about the world to receive
distress calls.
However, if a ship was outside of the normal shipping lanes or was
rapidly overwhelmed by the forces of nature, her distress alert may
go unheard.... many ships have gone to the bottom without any
distress signal being sent - they have "sunk without trace".....

The pre-GMDSS systems were, in reality, based on 1920's
technology....
A new system
The International
Maritime Organization (IMO) pondered the shortcomings of the
existing marine distress systems in the mid to late 1970's.
The 1979 IMO Assembly decided that a new global distress and safety
system should be established in conjunction with a coordinated SAR
infrastructure to improve safety of life at sea.
And so was born the Global Maritime Distress and Safety
System (GMDSS).
The GMDSS is designed to automate a ship's radio
distress alerting. It removes the
requirement for manual (i.e.: human) watchkeeping on
marine radio distress
channels.
The new system is quicker, more efficient and
reliable than the old manual Morse Code and radiotelephone alerting
systems.
The basic concept of the GMDSS is that Search and Rescue
(SAR) authorities ashore, as well as shipping in the immediate
vicinity of the ship or persons in distress will be rapidly alerted
so that they can assist in a coordinated SAR operation with the
minimum of delay.
One of the principal advantages of the GMDSS is that the system is
actually an amalgam of various individual radio systems, both
terrestrial and satellite. Distress alerts may be sent and
received over short and/or long distances, by ships of all sizes.
In other words, every ship is able to perform those communication
functions which are essential for the safety of the ship itself and
of other ships operating in the same area - irrespective of the area
through which it sails and its size...
DUNSTAN AND ASSOCIATES
The GMDSS specialists