between ships and SAR aircraft (all SAR aircraft are fitted, as a
minimum, with VHF Channels 16 and OG - as are survival craft
hand-held VHF radio sets).Additional 'intership' channels
Ch08, Ch72 and Ch77
Allocated exclusively in the international list for 'intership'
communications though they may be used for other purposes,
nationally, in some countries.
Ch09, 10, 13, IS, 17, 67, 69 and 73
Also available, internationally, as intership channels - but may be
allocated nationally to 'port operation/ship movement' services. You need
to check ALRS Vol. 6 to establish whether any channel you may want to
use for intership communications is not already allocated to a local port
operations/ship movement service.
Ch IS and Ch 17
May be used for 'onboard' communications between the bridge/
wheelhouse and deck - provided that you keep the transmitter output
power to I Watt (on bridge and hand-held sets). As these channels are
also available for port operations/ship movement services, you need to
avoid them if they are allocated for local harbour use (ALRS Vol. 6
refers).
Notes explaining restrictions in the use of some VHF channels are
included in ALRS Vol. 1 and ALRS Vol. 6 'Table of Transmitting
frequencies in the VHF maritime mobile band'.
INT IUS channels
When using equipment that allows you to switch from
INTernational to US channel selection, you will find additional channel
designators (e.g., WXI, WX2 to receive continuous weather broadcasts
in US waters; and OIA, 05A 88A). The 'N channels are 'simplex'
versions of the international channel with the same number {i.e., ChOl
on the INTernational setting on your radio is a duplex (separate transmit
and receive frequencies) channel; OIA is a simplex - single frequency-
channel). You cannot communicate with other vessels/shore on an 'A'
channel unless you change to the US setting on your VHF radio.
Some Canadian stations also make use of US channel selection
and will be identified in the appropriate ALRS (and in the Canadian
Coast Guard 'Radio Aids to Marine Navigation').
236 THE NAUTICAL INSTITUTE