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USCG: ‘Findings of Concern’ focuses on the hazards of corrosion

Originally posted on the USCG Maritime Commons 07/25/2019

The Coast Guard recently published Findings of Concern 009-19, “Corrosion Caused Casualties,” in order to bring awareness to unsafe conditions discovered last year on a Louisiana towing vessel during a marine casualty investigation. 

The Incident.

An Inspected Towing Vessel (ITV) pushing a loaded tank barge experienced a loss of steering and subsequently ran aground, Sept. 25, 2018. The marine casualty investigation determined the initiating event to be the port shaft propeller nut wedged into the rudder, which prevented the free and full movement of the steering gear. (Figure 1)

Photo of propeller nut wedged into the rudder and photo of deteriorated propeller nut locking strap.

Contributing Factors and Analysis

The investigation identified the initiating event causal factors to be a material failure of the port shaft propeller nuts locking strap (missing), the lack of a secondary securing mechanism (second nut/cotter pin) on the port propeller nut, and an inadequate corrosion mitigation preventative maintenance program. Visual analysis of the starboard shaft locking strap noted significant deterioration of the locking mechanism (Figure 2), requiring immediate replacement. Based on the analysis of this casualty, marine inspectors inspected the locking nut straps of several other ITV’s during scheduled dry-dock exams, which showed similar corrosion issues.

The Coast Guard recommends the following preventative measures:

  • Review company corrosion prevention systems/programs. If necessary, engage with a corrosion specialist from the American Boat and Yacht Council and/or National Association of Corrosion Engineers. 
  • Ensure adequate primary and secondary propeller shaft securing devices (cotter pins, double nut, locking strap, etc.) are in place at all times, with consideration given to vessel operations and environmental conditions.
  • Inspect propeller fasteners routinely/during every dry-docking and replace in accordance with manufacturer’s instructions. 

The Coast Guard issues findings of concern to disseminate information related to unsafe conditions identified as causal factors in a marine casualty and that may cause a similar casualty on other vessels. Findings of concern are intended to educate the public, state, or local agencies about the conditions discovered so they may address the findings with an appropriate voluntary action or highlight existing applicable company policies or state/local regulations. 

These findings of concern are provided for informational purpose only and do not relieve any domestic or international safety, operational, or material requirements. For any questions or comments please contact Marine Safety Unit Lake Charles Investigations Division by phone at (337) 491-7811 or by email at

USCG: Sub M COI Update


The Towing Vessel National Center of Expertise (TVNCOE) reports that approximately 750 COIs have been issued with another 450 currently in the queue. They believe this represents approximately 22% of the 25% of the fleet towing vessels needing COIs in by July 22, 2019 (year one of the four-year phase-in).

They estimate that 219 companies have received a TSMS certificate/DOC and are using an SMS for compliance that those companies represent roughly 3,250 towing vessels.

NTSB: MAB 01/13/2018 Barge Breakaway and Contact with the Emsworth Locks and Dams

The NTSB has released the Marine Accident Brief (MAB) for the Barge Breakway and Contact with the Emsworth Locks and Dams.

The incident occured on 01/13/2018 when 27 dry cargo barges broke free from the fleeting area near Pittsburgh, PA drifting uncrontolled downriver and eventually struck the Emsworth Locks and Dams complex as paraphrased from the report.

The report has recommendations for both the U.S. Army Corps of Engineers and the USCG. The primary focus appears to be on permitting and maintenance of fleeting areas along with requirements for procedures for operating in highwater and ice conditions.

Click here to download NTSB DCA18PM011 Barge Breakaway and Contact with Emsworth Locks and Dams