Route Message
The Route Message Broadcast is used as a means to indicate intended navigation and route information to nearby ships, allowing ships to avoid ending up in a close quarter situation where the involved ships have to comply with the COLREG rules. The current and a fixed number of coming route legs of the monitored route is shared with other ships.
On-board message flow
The ECDIS initiates any Route Message broadcast to be transmitted by the Communication Device, as well as any Route Message interrogations. The ECDIS will compile the Route Message data payload, or interrogation message payload, as defined in section 4, and send a BBM or ABM message with the payload to the Communication Device.
The Communication Device will provide the ECDIS with VDM-message data as they are received on the VHF data links.
VDM message payloads may be:
- Remote AIS target dynamic, static and voyage data (AIS Msg 1,2,3,5,9,18,19,24A,24B)
- Remote ship route message data (AIS msg 8 or VDES ASM msg 2)
- Route Message interrogation messages (AIS msg 4 or VDES ASM msgs) (AIS msg 4 could be send by VDES ASM msg 0)
The Route Message-payload is defined such that the current leg as well as up to twelve additional legs can be shared, with Cross Track Distance (XTD) parameters for each leg.
When no Monitored Route is active, the Route Message shall have an empty payload.
Two Route Messages are defined, depending on the communication system used. VDES ASM channel communication allows for a higher bitrate, and more data within the three timeslot limit.
Leg parameters (planned speed, XTD, geometry) are for the leg ending at the waypoint following those parameters. Turn radius is for the next waypoint