Channels 06, 8, 7'2 and 77 are the only channels which are
exclusively intership, and not also available for use in 'Port Operations!
Ship Movement' service. You can avoid interfering with harbour!ship
movement operations by checking ALRS Vo!. 6 for your area of operation
before using any of the other intership channels listed (to make sure that
no local harbour!ship movement service is allocated the channel
concerned).
Channel 06, as mentioned earlier, is the 'Primary Intership
Channel' - and must be fitted on all marine VHF sets. It is also used,
during Search & Rescue (SAR) operations, for communicating with SAR
aircraftlhandheld VHF liferaft sets. Although designated as the 'primary'
intership channel, Ch06 is probably one to avoid for routine ship-to-
ship communications if one of the others is free at the time.
Channel 10, 67 and 73 may be used, by some administrations, for
SAR operations or other safety communications (including Maritime
Safety Information broadcasts).
Channel 13 has been designated in the GMDSS for sole use for
'bridge to bridge communications concerning the safe movement of
vessels' - i.e., it should only be used, between two vessels, to aid safe
navigation of the vessels concerned. Ch 13 should not be used for normal
'ship'S business'.Note that Ch13, 09, 15, 17 and 69 are also available as 'Port
OperationslVTS' channels. If any of these channels are allocated to
a local port, you must avoid using that channel for intership
communications otherwise you may cause an incident by
interfering with local ship movements in confined waters.Intership communications - calling procedures
To contact another vessel using Marine VHF !SSB RadiO, you have
four options:
1 If your call is regarding the safe navigation of your own vessel and
the other vessel, you can call direct on Ch 13. All vessels should, when
practicable, listen on Ch13 when at sea - particularly in congested
waters. A voice call on Ch 13 should, therefore, allow you to make
contact.
2 You can make a routine DSC Call on Ch70 VHF, or on 2177kHz MF
(provided that you know the other vessel's MMSI) - offering a working
channellfrequency to the called vessel. The called vessel needs to
44 THE NAUTICAL INSTITUTE