Waterways Management Message

Introduction/Additional information: 
Release Version 2c:
            - Updated usage notes.
Release Version 2b:
            - Updated usage notes.

Release Version 2:
            - Added better linkage between vessels in subtype 0 (list) and subtype 2 (name).
- Revised message version field definition to limit it to 15 versions in accordance with RTCM recommendation.
- Fixed error in documentation that had message version field in a different place for the addressed version of the message.
- Updated usage notes.
- Added new subtype 2 message to define a vessel name for a vessel in list with unknown MMSI.
- Added ice convoy as a type.
- Set version to 2.
Release Version 1b:
            - Corrected some typos in the description fields, no change to message format.
Release Version 1a:
            - Changed usage notes to reflect Linked Text message vs. Text Description message. No change to message format.

1.1      Introduction

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 three sub-types of this message;
1) for providing a position/name of the waterway feature,
2) for providing a list of vessels and their sequence order/times, and
3) to specify a name (or IMO number) for a vessel with unknown MMSI.
Specific information for each vessel includes: sequence time, direction, and vessel MMSI. The complete list of message types is contained in Table 1.

1.2      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 Linked Text message). However, the same source MMSI needs to be included in both the Waterways Management and the Linked Text 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 1000000003-1000001023 can be used. The name or other identifier of the vessel is then transmitted in a subpart 2 message with the same number 3 – 1023 used to link the vessel name with the position in the queue. These numbers will be used sequentially by the competent authority transmitting the lock queue and then re-used once the range is exhausted. A range of 1020 numbers should be more than sufficient so that by the time the numbers are reused there is no confusion.
  • All of these special “MMSIs” are 10digit numbers so as not to be confused with real MMSIs.
  • Subtype 2’s sent as needed along with the subtype 0’s to specify name or number for vessels with unknown MMSI. Anywhere from 0 to 7 subtype 2’s sent with each subtype 1 message.
  • New subtype 2 messages should be generated each time the vessel list is updated (subtype 0 message).
  • A message version number is encoded as part of the message; if the received version number is different than what the display system has been programmed for, the data should be ignored.
  • Positions are in WGS 84 Datum.
  • Typical transmission sequence would be subtype 1 message at a longer interval (10min perhaps) and then subtype 0 and 2 at a shorter interval (perhaps 3 min).
  • The display system should remove the WWM message from the display 60 minutes after the time of the last vessel in the list unless a removal message is received sooner.
Message number: 
Used by: 
Number of slots (max): 
Reporting Rate: 
Nominally every 5 minutes.
How portrayed: 

As list linked to the geographic feature.

Technical point of contact: 

Submit any suggested changes to: gwjohnson@alionscience.com


See PDF document.