In the 70s ships became larger and cruised smaller it was not considered
economical to employ professional radio officers anymore and monitoring radio
communications became the responsibility of deck officers unfortunately some
distress calls from ships in need of help were missed the International
Maritime Organization the United Nations agency concerned with shipping felt
compelled to act the result was the GM DSS which since 1999 legally requires
all vessels over 300 gross tons or that carrying more than 13 passengers to
carry specific equipment the system aims to make best use of all types of
communication technology including radio satellite and digital it was decided
that all compulsory thick vessels should carry at least two methods of sending
and receiving distress messages the equipment carried depends on the area in
which the ship operates the GM DSS divides the sea into four areas defined
by their proximity to shore based or satellite receiving equipment area one
is within range of VHF radio Coast stations area two is within range of M F
medium frequency radio Coast stations area three is between 70 degrees north
and seventy degrees south and covered by the Inmarsat satellite communication
system area four covers the polar regions and therefore for our purposes
at least is irrelevant in addition to VHF compulsory fit vessels are required
to carry a number of other pieces of equipment
these include radar or waterproof handheld radios EPIRBs that's emergency
position indicating radio beacons and search and rescue transponders and nav
Tech's some of these may be unfamiliar to small
boat users so let's take a look at them here eeep herbs are portable self
powered radio beacons that once activated send a signal to the
cospas-sarsat satellite system these polar orbiting satellites store
the signal until they can send it down to an available earth station which in
turn passes it on to a Rescue Coordination Center the beacons
transmitted on 406 megahertz many of the latest models have built-in GPS
receivers the information from the GPS is also transmitted to the satellites
giving a casualties position to within a hundred and twenty-five meters eg perb
has a unique number which should be registered in the UK this is done with
HM Coastguard of Falmouth if an ePub is accidentally activated don't turn it off
until the Coast Guard has been informed if the signal suddenly disappears they
will assume you have sunk search and rescue transponders or sart's a homing
devices designed to help rescuers locate vessels in distress they are activated
by radar waves and then show up on a radar screen like this at first the
casualty is located by a line of twelve dots along the bearing towards them as
the rescuer gets closer the dots become increasingly bigger arcs until when they
are right next to the transponder they become circles with the sort at a height
of 1 meter they have a range of approximately 30 miles for aircraft of 5
miles for ship NAVTEQ s-- is the part of the GM DSS that provides weather
forecasts and navigational warnings the information is received automatically
and displayed in text form on a screen modern units operate on two frequencies
one for the local language and the other for English they have a range of about
400 miles the units menu system is used to select which Coast stations are
monitored and the types of information displayed each transmitting Coast
station is identified by a letter they're listed in the nautical Almanac
whilst there is no legal necessity for pleasure yachts to carry any of this
equipment they will always carry some of it for instance a VHF radio and an ePub
for coastal work with the addition of a small
immerse at for offshore passages would be prudent