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USCG: Improper AIS Setup Raises Risk for Towboat Operators

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Illustration of the ECDIS symbology resulting from improper (left) and proper (right) AIS setup for towboat pushing ahead (USCG)

By The Maritime Executive 05-17-2020 07:10:25

The U.S. Coast Guard is warning inland towboat operators to set up their AIS transponder to broadcast the full size of the barge tow, not just the size of the vessel. According to the brief, improper AIS setup may have been implicated in a recent collision between two towboats on the Mississippi - likely the RC Creppel and Cooperative Spirit, which collided outside of New Orleans in January. (The USCG did not name the vessels in the bulletin, but the particulars of the accident precisely match the January collision.) Although the investigation into the casualty is not yet complete, the USCG has released an interim warning to the towboat community about the hazards created by inaccurate AIS data.

In the casualty in question, two towing vessels were approaching a bend on the Mississippi River before sunrise. Neither vessel was broadcasting the total overall length of their tow to other AIS users, according to the USCG. As the vessels rounded the bend and completed their turns, they collided, causing one to capsize and sink with multiple fatalities.

The first vessel’s AIS broadcast showed its length at 72 feet (the size of the RC Creppel), but the overall length of the vessel and its two-barge tow was more than 670 feet. The second vessel’s AIS broadcast showed its length at 200 feet (the size of the Cooperative Spirit), but the overall length of the vessel and its 40-barge tow was 1,600 feet. Without information regarding the total length of the other vessel and its tow, the operators did not have a full understanding of the pending passing situation, the Coast Guard assessed. 

"Proper function of the AIS is dependent on accurate vessel data entry, including entering the proper ship type code and the full length of a vessel and its tow. 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," the USCG warned. "Given the wide variety of sizes and lengths of tows, and the heavy density of these types of vessels traveling on the country’s marine transportation system, accurate AIS input is vital to an operator’s ability to make informed navigational decisions."

In order to minimize risk, the agency's Directorate of Inspection and Compliance recommends that operators should:

- Use the Coast Guard's AIS Encoding Guide to ensure that accurate and up to date information is entered into the AIS.

- For vessels towing ahead or alongside, use Ship Type 57 (not Ship Type 31) within the static data fields in order to broadcast the overall dimensions of the vessel and its tow.

- Ensure towing vessel officers have the training and resources to update AIS data when tow sizes change.