NTSB: Wake From Passing Ships Pushed Barge Tow Into Algiers Lock Gate
The National Transportation Safety Board has released its final report on the allision of the towing vessel Kitty (and its tow) with the Algiers Lock in New Orleans. A deluge of water coming into the lock from the wake of passing vessels likely caused the tow to surge forward and strike the lock gate, NTSB concluded.
On the evening of July 4, 2023, the 68-foot towboat Kitty was pushing two tank barges into the Algiers Lock during low water conditions, from the Mississippi River side. The river stage at that point in the summer was 1.7 feet at Algiers Lock, an "extremely low" water level. A severe-wake warning was in effect because of the amplified risk of wave action in the shallows on either side of the shipping channel, but there were no specific speed restrictions in place. River pilots maintained standard transit speeds (full ahead) through the area.
At 1752-1802, just before the Kitty entered the lock, three deep draft ships passed by on the river at ordinary transit speeds of 10-14 knots. At 1804, the tow suddenly accelerated ahead in the lock chamber. Despite the master putting all engines full astern, Kitty and her barge tow were pushed forward. The momentum parted two mooring lines, and the lead barge struck one of the lock gates. No injuries or pollution occurred, but the lock gate sustained about $2 million in damage.
After the casualty, the crew of the Kitty reported that the water level had risen by three feet or more while transiting the lock. NTSB examined video footage from the accident and concluded that the wakes of the passing vessels caused the surge of water into the lock, and raised the water level by at least 3.4 feet.
Lock operators told NTSB that they had never seen anything like this before, though smaller surges of up to a foot had occurred previously. It was the lowest water level that they could recall as well; NTSB suggested that the extremely low water in the lock forebay could have amplified the effect of the wake, creating the unusual surge that pushed the towboat forward.