202054 AIS needs correct manual input

As edited from USCG Safety Alert 04-20

In the early morning, before sunrise, two towing vessels were approaching an almost 90° bend on a river in opposite directions. Neither vessel was broadcasting the correct total length of their vessel and tow to other AIS users. The first vessel’s AIS broadcast showed 22 metres, yet the overall length of the vessel and its two-barge tow was 205 metres. The second vessel’s AIS broadcast showed 61 metres, but the overall length of the vessel and its 40-barge tow was 488 metres. As the vessels rounded the bend and completed their turns, they collided, causing the down-bound towing vessel to capsize and sink with several fatalities.

The accurate display of a vessel’s full length becomes particularly important in situations that prevent vessels from seeing each other until they are in very close proximity.

Lessons learned

• AIS is a valuable tool that shares critical vessel information with other vessel operators. However, the usefulness of AIS is dependent on accurate vessel data entry.
• While correct overall length is important for all vessels, tug and tow operations are particularly vulnerable to errors due to the changing value of their total length with each job.
• Incorrect AIS information will give a false mental picture to other vessel operators in the vicinity and can contribute to accidents.