3 classes of ais data – Raymarine C140w User Manual
Page 136
10.3 Classes of AIS data
There are two classes of AIS data; each class supports a different
range of AIS data.
AIS data is defined as Class A or Class B. The sending and
receiving of Class A data is compulsory for larger vessels. You will
therefore be able to view all larger vessels on your AIS display.
Class B data is applicable to smaller vessels and is not compulsory.
You should not therefore assume that your AIS is displaying all
smaller vessels in your area.
Note: Not all AIS receivers will decode all information and not
all of the Class A vessels input all of the required AIS data. For
example, some inexpensive AIS Class B receivers do not decode
and output information such as the ship’s name, IMO number and
vessel draft/beam/length, destination and so on.
Your AIS receiver or transceiver may support additional AIS data
that is not decoded by the multifunction display.
The following table lists the AIS information that is decoded by your
multifunction display. (Y = Yes; N = No):
Data
Class A
(receive)
Class B
(send)
Class B
(receive)
Ship’s name
Y
Y
Y
Type
Y
Y
Y
Call sign
Y
Y
Y
IMO number
Y
N
N
Length and beam
Y
Y
Y
Antenna location
Y
Y
Y
Data
Class A
(receive)
Class B
(send)
Class B
(receive)
Draft
Y
N
N
Cargo
Information
Y
Y
Y
Destination
Y
N
N
ETA
Y
N
N
Time
Y
Y
Y
Ship’s position
Y
Y
Y
COG
Y
Y
Y
SOG
Y
Y
Y
Gyro heading
Y
Y
Y
Rate of turn
Y
N
N
Navigational
status
Y
N
N
Safety message
Y
N
Y
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