The following is the text of an accident brief from the National Transportation Safety Board:
The towing vessel Justice was heading to Buzzards Bay, Mass., with five crewmembers when it grounded on a hard, rocky bottom southwest of Cape Cod Canal, just outside Hog Island Channel on March 21, 2013. The impact, at 0001 Eastern Daylight Time, sheared the starboard stern drive from the vessel and resulted in the discharge of 232 gallons of gear oil. The vessel docked 15 minutes later without further incident using its remaining port stern drive. No one was injured.
The National Transportation Safety Board determines that the probable cause of the grounding of the commercial towing vessel Justice in Hog Island Channel was the mate's ineffective use of the vessel's autopilot to maintain a course within the navigable channel and his delay in taking manual control as the vessel approached charted hazards.
Click here to view the complete report.