NTSB: Two Tankers Had the Same Accident in Two Years on Cooper River

The NTSB has determined that the tanker Hafnia Amessi struck a pier on the Cooper River last year because the pilot let the vessel get too close to the riverbank. The combination of bank effect and current overwhelmed the force of the tanker's rudder and propulsion, sending it into the end of the pier - much like the tanker Bow Triumph, which hit the same pier under similar circumstances in 2022.

"Bank effect can have an undesired effect on vessels, even for the most experienced ship handlers. Pilots, masters, and other vessel operators should consider the risks in areas known for shoaling when planning transits," cautioned NTSB. "Where appropriate, employ additional measures to mitigate the risk, including use of tugboats, reducing or increasing speed, and/or delaying the transit until more favorable conditions exist."

On the morning of January 14, 2024, Hafnia Amessi finished offloading at a terminal on the Cooper River in Wando, South Carolina. The vessel prepared to get under way on a ballast voyage to Texas City, Texas. A local marine pilot with 25 years' experience and 5,000 transits - including more than 20 on this stretch of river - boarded to guide the outbound transit. Because the pilot was aware of the Bow Triumph's allision with Naval Weapons Station Pier B two years before, he instructed the escort tug to take a position on the starboard side and accompany Hafnia Amessi down the river as a precaution. "This order was a direct result of what I had learned from the Bow Triumph incident in 2022," he told NTSB.

Hafnia Amessi got under way. At 1000, nearing a river bend at buoy 80, the pilot noted an extreme flood current rushing past the buoy - strong enough to reduce the tanker's speed to just five knots.

The pilot lined up to take the next bend, a hard 90-degree turn to port that would take the tanker past Pier B. The pilot aimed for the east side of the channel, expecting that the strong current would set Hafnia Amessi further out towards the center. That did not occur, and the tanker ended up passing tight against the eastern bank, a maneuver that the pilot had not intended. The eastern bank had a ledge that tended to shoal rapidly with silt, and it had to be dredged every few years.

At 1016:27, the pilot ordered hard to port, but the rudder order had no effect on the rate of turn. At 1017:23, the ship's echo sounder read zero feet, indicating shallow water. Pier B was dead ahead, and the pilot ordered full ahead to push more water over the rudder. He also directed the escort tug to push on the starboard bow with "all she's got."

Courtesy NTSB

The last-minute maneuvers were not enough to avert an allision, and Hafnia Amessi hit the end of the pier at six knots. The impact dented in the tanker's hull plating up to three inches and buckled three transverse bulkheads inward by about 1-2 inches, causing about $30,000 in damage. The end of the pier sustained about $8 million in damage to dolphins, pilings and concrete, in addition to the previous damage caused by Bow Triumph. (There was no disruption to cargo operations at the pier, as it was already out of service because of the earlier accident.)

According to NTSB, bank effect from a known shoal on the eastern channel edge likely pulled Hafnia Amessi's stern to port. Meanwhile, the strong flood current pushed her bow to starboard. The effects were strong enough to neutralize the force of Hafnia Amessi's rudder, even hard over to port with engine full ahead.

NTSB noted that Bow Triumph's allision with the same pier happened under very similar circumstances: the Triumph passed too close to the east side of the channel, suffered bank suction, lost effective control of her heading and destroyed a 300-foot section of the pier.

The shoal was a known hazard, and the Coast Guard had previously scheduled the installation of a buoy to mark the danger zone at the bend. The buoy was installed on the planned date, three days after Hafnia Amessi hit the pier. "If this Buoy 72A had been there [during the transit] . . . that would have given me the tools to come more to the right and the information that I needed to avoid that spot," the pilot told NTSB after the casualty.

After two allisions in two years, the Coast Guard Captain of the Port issued a standing order requiring all vessels over 10,000 GT or drawing more than 25 feet to use a tethered, two-tug escort when transiting through this challenging section of the river.