Ian Waugh - A Mariner\'s Guide to Marine Communications

acknowledge your DSC Call, also by DSC, accepting or changing

the working channel!frequency. (There's no point in you going to the

voice channel unless you receive the DSC Ack' - if the other vessel

did not receive your DSC Call, they won't move to the voice channel).

3 The preferred option, for vessels who talk together regularly on

intership voice channels, is to agTee a normal working channel!

frequency and monitor that channel. On VHF Radio, you can use

Dual Watch or Scan mode. Some Marine SSB Radios also offer a
Scan facility. (Calling direct on working channels reduces the number
of DSC calls).
4 If the craft you want to call is 'non-G MDSS' and does not have DSC
facilities; is a GMDSS vessel but you don't know their MMSI; and
you don't know which (voice) working channel they might be
monitoring - call by voice on Ch16.
When two ships want to have a normal intership conversation, the
called ship is the 'controlling station' That means that the called ship
will decide which working channel to use (even though the calling station
may have suggested one in the DSC/voice call) and will make the first
voice call on the working channel - e.g:

Ch70 DSC Call from WizardtoJustina, suggesting Ch06 as the working

channel.

Ch70 DSC Ack' fromJustina, telling Wizardto go to Ch72 (no further

Ch 72
Ch 72

Ch72

DSC response required from Wizard).
Wizard this isJustina,Justina - Over.
Justina this is Wizard-nets all onboard and returning to harbour,
Over.
Wizard this isJustina - Received - I'll be finished in about one
hour - see you back in harbour - Out.
When conditions are good (which you would expect on VHF on
most occasions) the initial voice call should take the form shown above,
namely: 'Station Called (once) this is Station Calling (twice) - Over' Once
contact is made, you can revert to ship's names once.

As a general rule, your first call should be made on low power, and

only move to high power if you fail to make contact. Although VHF

is 'line of sight' - where the power output should not, in theory,

affect range - a one-watt Signal will not be strong enough to 'lift the

squelch' on a receiver which is more than a few miles away.

MARINE COMMUNICATIONS 45