The National Transportation Safety Board (NTSB) has issued Marine Accident Brief in order to inform on the Collision between Towing Vessel William E Strait and Margaret Ann Tow, with subsequent partially sinkng of e William E Strait.
On December 14, 2015, at 1122, the uninspected towing vessel Margaret Ann was downbound on the Mississippi River pushing 3 tank barges loaded with liquid asphalt when its tow collided with the uninspected towing vessel William E Strait, which was pushing a flotilla of 30 loaded gravel barges.
As a result of the collision, barge MM-66 sustained a hull penetration to its stern void and broke free from the tow string of the Margaret Ann, while barge MM-41B received damage to its bow and forward deck area. Both barges had significant structural damage as well. The William E Strait sustained a 6-foot by 5-foot opening in its hull at the point of impact, which allowed rapid flooding of the engine room. Additionally, the force of the collision pushed the port bow of the William E Strait into barge MTC 6401, which was in the last row of its tow flotilla, holing the barge’s stern void.
The pilot on the William E Strait managed to maneuver the vessel and its flotilla back to the left bank with the assistance of the uninspected towing vessel Paige L Strait. The crew then boarded the aftermost barge in the flotilla before the William E Strait partially sank and came to rest on the river bottom with the uppermost structure of the vessel still above the water’s surface. The Margaret Ann, with the assistance of the uninspected towing vessel Lee Leavell, recovered the MM-66 and proceeded to McKellar Lake, just off of the Mississippi River near the accident site. There it began pumping out the water in the stern void of the MM-66 while awaiting the arrival of Coast Guard personnel.
The pilot on the William E Strait told investigators that he felt his vessel was holding position on the left bank, as he had agreed to do, until he engaged forward propulsion and steered to starboard in an effort to swing his stern back toward the bank. He said that these maneuvering actions were taken to avoid the collision. Based on his perception, the Margaret Ann had not swung wide enough toward the right bank and its heading was such that it appeared to be bearing down directly upon the stern of the William E Strait.
Findings
Investigators reviewed playback information from ECSs and extracted position data from the AIS transmissions of both vessels. The data indicated that the position of the William E Strait from 1559 on December 13, 2015, through approximately 1010 on December 14, 2015, remained relatively constant just off the left bank. During this period, there was little variation in the broadcasted AIS speed, true heading, course over ground, latitude, or longitude of the vessel.
From 1011 through 1119, the data indicated that the William E Strait began a slow, continuous shift of position in a westerly direction of about 739 feet toward the Global Materials West Memphis, Arkansas, lower dock. The approximate width of the channel from the left bank to the Global Materials lower dock is 1,880 feet. The vessel’s true heading decreased gradually from 180 degrees at 1100 to 163 degrees at the time of collision. Although the data indicated that the
William E Strait managed to attain some forward and downriver movement in the moments just prior to the collision, the true heading of the vessel remained at 163 degrees, and there was no appreciable swinging of the vessel’s stern back toward the bank. Therefore, it is likely that this movement was the result of the river current acting on the port aft area of the vessel and its tow.
The pilot of the William E Strait did not hold the vessel and tow’s position along the left bank as he had agreed to do when arrangements were made with the pilot on the Margaret Ann. Additionally, his attempt to apply forward propulsion and starboard rudder in an effort to swing
the stern of the William E Strait back toward the bank was neither timely nor effective.
Probable Cause
The National Transportation Safety Board determines that the probable cause of the collision between the Margaret Ann and the William E Strait was the William E Strait pilot’s inability to hold his vessel in position along the left descending bank, as had been agreed on, to allow the safe and unimpeded passage of the Margaret Ann.
Further details may be found by reading the report below
Source & Image credit: NTSB
