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
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...