Route Message

Introduction/Additional information: 

Sharing and receiving Monitored Routes

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.

The use of this message requires that both the receiving and transmitting ship has the appropriate communication equipment as well as presentation and navigation systems


The Route Message structures are defined

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.


The first and last waypoints are fully qualified, while intermediate waypoints are defined as the difference from the previous waypoint in the route. This way of defining intermediate waypoints saves bits but limits the maximum length of those legs. In cases where representable length is insufficient, the total route segment reported in a message is cut short and the “intermediate” waypoint becomes the last waypoint in the message.

Permitted as from: 
Danish Maritime Authority
Message number: 
in force
Number of slots (max): 
Last modified: