Waterways Management

Introduction/Additional information:

The Waterways Management message can be used to facilitate vessel traffic movement in confined waters. More “directive” than advisory, this message can be broadcast (e.g., information for all ships or a group of ships) or addressed (e.g., information/direction to a single ship). Examples include: lock, gate, narrows, or single passage area.
There are two sub-types of this message; 1) for providing a position/name of the waterway feature, and 2) for providing a list of vessels and their sequence order/times. Specific information for each vessel includes: sequence time, direction, and vessel MMSI. The complete list of message types is contained in Table 5.

Usage Notes

  • The message can be broadcast or addressed, depending on which alternative is more appropriate.
  • If message sub-type 0 is used, then a message sub-type 1 must also be sent to define the position for the sub-type 0 sequence. The message sub-type 1 can be transmitted less frequently than the sub-type 0 if desired.
  • The Message Linkage ID can be used to link additional text (e.g., a separate text message). However, the same source MMSI needs to be included in both the Waterways Management and Text Description message.
  • If there are no vessels in the queue then the MMSI of 0000000000 can be used for the first vessel with the time being the time of the data report.
  • If the MMSI of the vessel is unknown then an MMSI of 1000000003 can be used. An additional text message (with the message linkage ID) can be used to transmit the vessel name as text if desired.
Message number:
Number of slots (max):
Reporting Rate:
Reporting rate is a function of the number of vessels and how quickly the information changes. Nominally every 5 minutes.
How portrayed:

Portrayed as a text list linked to geographic location on the chart.

Permitted as from:
Technical point of contact:


Parameter # of Bits Description
Standard Message Header Message ID 6 Identifier for Message 8; always 8.
Repeat Indicator 2 Used by the repeater to indicate how many times a message has been repeated. 0 – 3; 0 = default; 3 = do not repeat any more. Set to 0 (default).
Source MMSI 30 MMSI number of source station. This varies according to the transmitter ID.
Spare 2 Not used. Set to zero.
Binary Data Designated Area Code 10 Designated area code (DAC). This code is based on the maritime identification digits (MID). (See Rec. ITU-R M.1371-3 § 2.1, Annex 5). Set to 366 (US).
Function Identifier 6 Function identifier. The meaning should be determined by the authority that is responsible for the area given in the designated area code. Set to 35.
Application Data Message Linkage ID 10 Identifier for the Waterways Management event. This number uniquely identifies an event and is used to connect additional information with the event. Source MMSI and this ID uniquely identify the event.Set to 0-1023 by message originator.
WM Type 4 Waterways Management Type as per Table 5.Set to 0-15 according to type.
Subtype 2 Message subtype.0 = Sequence; 1 = Name/Position; 2-3 = (reserved for future use).Set to 0 – Sequence.
Vessel 1 56 First vessel. Structured as in Table 6.
Vessel 2 56 Optional second vessel. Structured as in Table 6.
Vessel 3 56 Optional third vessel. Structured as in Table 6.
Vessel 4 56 Optional fourth vessel. Structured as in Table 6.
Vessel 5 56 Optional fifth vessel. Structured as in Table 6.
Vessel 6 56 Optional sixth vessel. Structured as in Table 6.
Vessel 7 56 Optional seventh vessel. Structured as in Table 6.
Total bits 128 – 520 1-3 Slot Binary Message
Sample WM