NTSB: Pilot underestimated current in Kentucky towboat sinkingJul 31, 2018 03:08 PM
A towboat that sank last year in the Mississippi River near Columbus, Ky., was handling a string of barges when it lost control in the strong current and became pinned against a downriver barge fleet.
Todd Brown and another towboat were removing debris from the four-barge string when it went under at about 1530 on April 17, 2017, according to a National Transportation Safety Board (NTSB) report. No one was injured, but the incident at mile marker 940 caused extensive damage to the 40-year-old vessel.
The NTSB determined “the probable cause of the collision and sinking of the uninspected towing vessel Todd Brown was the pilot’s underestimation of the effect of the river current on the barge string being maneuvered during a de-drifting operation.”
Although the 1,800-hp Todd Brown and 1,020-hp Ot Adkins met minimum recommended horsepower ratings, the NTSB determined both were underpowered for the prevailing flood conditions.
“Their horsepower was insufficient for overcoming the river conditions when the port side of the barge string became exposed to the 8-mph current,” the report said.
The sinking occurred in the Lower Mississippi roughly 20 miles south of the confluence with the Ohio River. Nearby river gauges registered 36 feet, or major flood stage.
Debris collects against barge fleets moored along the riverbank throughout the year, particularly during the spring floods. Clearing this debris is known as “de-drifting,” and it entails moving barge strings toward the center of the river and angling the bow into the current, the report said. The moving water flushes away accumulated debris.
Todd Brown and Ot Adkins prepared to de-drift a barge string from the No. 8 fleet at about 1500 on the day of the accident. Todd Brown’s pilot faced up to the aft end of the four-barge string, and Ot Adkins faced the starboard side of the lead barge.
“The pilot of the Todd Brown then began to maneuver his towboat to reposition the head of the barge string into the river,” according to the NTSB. “As the head of the barge string moved out into the river, a larger area of the barge string’s profile was exposed (to the current).
“Despite having its engines at full ahead, the Todd Brown, along with the string of four barges, began moving astern,” the report continued.
Ot Adkins attempted to push the lead barge toward calmer water along the riverbank. Yet the barges continued to drift astern, and Todd Brown’s pilot ordered a crewmember to disconnect from the barge string.
“Once it was unfaced, the pilot maneuvered his vessel to the port side of the drifting barge string, toward the more shallow west bank of the river,” the report said. “Consequently, the Todd Brown became trapped behind the moving string of barges and collided with the lead barges of the No. 9 fleet, about 250 feet downriver.”
The drifting barge string pinned Todd Brown against the No. 9 barges. After sounding the general alarm, the pilot and five other crew escaped onto nearby barges. The towboat quickly listed to starboard, swamped and sank in 35 feet of water.
Ingram Barge Co. of Nashville, Tenn., owns Todd Brown. The company had issued a memorandum in 2016 governing de-drifting after a large debris pile caused about 80 barges to break away. One provision called for using a standby towboat with more powerful engines during de-drifting operations. There is no mention in the NTSB report of a third towboat standing by during the 2017 accident.
The U.S. Coast Guard has issued advisories recommending that towboats have at least 240 hp for each barge moved during periods of high water. Todd Brown and Ot Adkins met that threshold but were still insufficient, the report said.
Rather than move toward shore, where Todd Brown became trapped behind the drifting barge string, the NTSB suggested the pilot should have steered toward the center of the river, away from the drifting barges and downstream fleets.
Salvage crews raised Todd Brown five days after the incident. It sustained about $1.5 million in damage to decking, the superstructure and internal compartments. Ingram Barge declined to comment on the NTSB findings.