NTSB Releases Accident Brief Detailing Bridge Allision On Atlantic Intracoastal Waterway
The National Transportation Safety Board (NTSB) has released its Marine Accident Brief detailing the investigation into the August 19, 2020, allision of the mv. Old Glory, which was pushing a single loaded hopper barge, with fendering at the base of the Peter P. Cobb Memorial Bridge, at Mile 965 on the Atlantic Intracoastal Waterway near Fort Pierce, Fla.
The incident occurred about 2:51 a.m., with no reported injuries to the crew or pollution. The impact caused an estimated $5,000 damage to the barge, while the bridge’s fendering system suffered $641,000 in damage.
The Old Glory had departed from Hillsboro Beach, Fla., at about 7 p.m. August 17, 2020, pushing the 230-foot-long hopper barge that was loaded with 1,600 pounds of dredge material. The total length of the tow was 281 feet, with a beam of 45 feet. Crew change took place at midnight August 19, 2020, with the relief captain taking over for the captain.
According to the NTSB, as the Old Glory approached the Peter P. Cobb Memorial Bridge, the relief captain called the on-duty deckhand up to the wheelhouse to serve as a lookout. According to AIS data, the vessel had a forward speed of 5.5 mph. with a course over ground of 337 degrees as it drew near the bridge. Gradually, according to the relief captain, the current was setting the tow to the west side of the channel. According to the NTSB report, at 2:46 a.m., the vessel’s course over ground had shifted to 333 degrees, with the bow of the barge beyond the western channel boundary.
At 2:48 a.m., a quarter of a mile from the bridge, the mv. Old Glory’s speed was 5.9 mph., and its course over ground was 331 degrees, with the entire tow outside of the channel “by about 65 feet, in an area with depths of 7.6-8.6 feet (based on the tidal conditions at the time),” according to the NTSB’s report. The relief captain corrected course, and by 2:49 a.m. the tow was within the western boundary of the channel with a speed of 6.1 mph. and a course of 336 degrees.
Again, as the tow neared the bridge, the current “set the tow to the west,” the report said. The relief captain noted that, about the same time, the vessel crossed into the approach to the Fort Pierce City Marine channel, which runs perpendicular to the waterway. That channel is maintained at a depth of 6.5 feet. In that area, the relief captain noted that the Old Glory “started bogging down” and that he was unable to “bring the head back up.” Nearing the bridge, the course over ground veered to 358 degrees. The relief captain attempted to “back down,” but the vessel did not respond, leading him to believe the vessel had either run aground or that its wheel wash was going against the barge.
As the barge entered the span, the relief captain, “believing the tow could not safely pass beneath the bridge, steered the head of the tow into the bridge’s east fendering, which he considered the safest place for the barge to strike since it did not affect any of the bridge structures,” the report stated. The bow impact damaged a 55-foot section of the eastern pier’s fendering, and the port side of the barge rubbed up against the western pier’s fendering.
The vessel and barge remained wedged in the span until the tide changed, which helped the tow straighten out, according to the relief captain. The crew reported the incident to the Coast Guard and the vessel owner, then was able to get underway again by 6:35 a.m.
While the barge received an indentation in the incident, the bridge’s fendering system had damage to four of its 11 sections. The bridge’s navigation lighting system also received damage. The bridge incurred no damage. Repairs to the fendering system were completed in January.
According to the NTSB, the relief captain reported that he was “caught off guard” by the swift current at the bridge, because he thought he was passing through the bridge at low tide. However, weather forecasting near the area actually predicted low tide to occur at 3:40 a.m., and navigational charts for the area described the bridge as a “strong cross” area with “extremely fast” currents.
That miscalculation by the relief captain proved pivotal to the allision, the NTSB stated.
The NTSB determined the likely cause of the incident was “an inadequate navigational assessment that did not identify the risk of strong cross-currents in the area of the bridge transit.”