RNLI Atlantic 85, Manual

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Activity 6 - Communications
B Class Atlantic 85 Manual – First Issue, June 2017
Activity 6 - Communications
Crew communications and control units
The Atlantic 85 inshore lifeboat is fitted with a Graytronics
Intercom System. The system provides 3 crew with general
functions and the fourth seat with limited functionality,
those function are as follows:
• Intercom communication between crew stations
• Transmit and receive audio over the VHF radio
• Receive audio from the Direction Finder (DF)
The system comprises a Master Control Unit (MCU)
mounted inside the console and four Crew Control Units
(CCU). Each CCU provides as a minimum a microphone
mute function, volume control and headset connector.
Certain CCUs also allow the user to select which radio to
listen to. A remote press-to-talk (PTT) button is fitted to
the helm CCU and an additional fist mic is fitted to the
crew 2 CCU.
Helm, crew 2 and crew 3
There are four different CCUs fitted to the Atlantic 85.
The helm, crew 2 and crew 3 CCUs are full-function units
and provide the maximum amount of control over the
intercom system. The significant difference between crew
2 and crew 3 units is an additional fistmic fitted to the
crew 2 CCU. The crew 4 CCU is a limited-function unit and
provides a reduced set of features.
Each full-function CCU is fitted with a headset breakaway
connector and a volume control which adjusts the volume
of both the left and right ear pieces together. There is no
difference in what should be heard from each earpiece.
The RADIO selector switch allows the crew to listen
to either the VHF radio (A), or the DF (B). In the normal
configuration the “RADIO C” port is not connected
however some boats have an additional VHF or an
alternative radio fitted and connected to RADIO C as
an exception.
The MIC selector switch allows the crew to switch off the
microphone (MIC OFF) in which case it will not be possible
to speak over the intercom system or VHF radio. The PTT
button will however continue to operate even when MIC
OFF is selected, however, this will only transmit silence
over the selected VHF channel as the MIC is not active.
CONFERENCE mode allows normal intercom operation
where anything that is spoken is heard by the other crew.
RADIO ONLY mode causes whatever is spoken to be
routed to the selected radio only and will not be heard by
other crew over the intercom.
A crew member using a full-function CCU will always hear
intercom audio, regardless of the position of the selector
switches. Additionally, where another crew member is
transmitting over the VHF radio and has CONFERENCE
mode selected at their CCU, whatever is transmitted over
the VHF will be heard by other crew through the intercom
system and likewise anything transmitted through the
intercom will also be transmitted over the VHF.
A PTT button is fitted either to the throttle arm (helm) or
on the front panel of the CCU (crew 2 or crew 3). The PTT
button will only cause the VHF radio to transmit when the
RADIO selector switch is set to RADIO A at the CCU where
the PTT button is pressed. There is no PTT button available
at the crew 4 position.
Helm CCU
Crew 2 and 3 CCU