美国国家运输安全委员会4月10日公布，2024年1月14日，一艘油轮在南卡罗来纳州查尔斯顿联合基地海军武器站附近航行时，因引航员操作失误导致船舶过度靠近河岸，最终撞击码头。  

事故细节显示，这艘长604英尺的"Hafnia Amessi"号油轮在库珀河航行时撞上B号码头。

当时由查尔斯顿分支引航员协会的一名引航员负责操纵，事故造成船体侧板及码头共计810万美元损失，未引发污染或人员伤亡。  

调查发现，油轮在河道弯道右转后，引航员为准备后续左转开始偏向航道东侧。

在此过程中，船舶受"岸壁效应"影响——当船舶在受限水域航行时，船首会被推离岸壁而船尾被吸向岸壁。

尽管引航员后续发出舵令及车令，仍未能抵消该效应，最终导致碰撞。  

除岸壁效应外，调查还指出油轮在转弯时遭遇涨潮流影响。

当船首驶出东岸阴影区时，水流作用于左舷船首水下部分，进一步阻碍船舶转向。

值得注意的是，这已是B号码头第二次发生同类事故——2022年"Bow Triumph"号油轮同样因引航员使船舶过于靠岸导致碰撞。  

美国海岸警卫队查尔斯顿港务长已颁布新规：要求所有总吨位超1万吨或吃水超25英尺的船舶在B号码头至斯诺角航段必须配备两艘系缆拖轮护航。

报告特别强调："即使对经验最丰富的操船者而言，岸壁效应仍可能造成意外。引航员和船长在通过浅滩区域时，应综合考虑拖轮协助、航速调整或延迟航行等风险缓解措施。"  

▲Image Credits: US Coast Guard

英文原文

A tank vessel struck a pier at Joint Base Charleston’s Naval Weapons Station in South Carolina after a pilot allowed the vessel to get too close to a riverbank, the National Transportation Safety Board said Wednesday.

The 604-foot-long tanker Hafnia Amessi struck Naval Weapons Station Pier B while transiting the Cooper River on Jan. 14, 2024. A Charleston Branch Pilots Association pilot was navigating the vessel, which sustained damage to its side hull plating. The contact resulted in $8.1 million in damages to the vessel and pier. No pollution or injuries were reported.

After making a right turn at a bend in the channel, the pilot began to favor the eastern side of the channel as the vessel approached the next bend, a left turn. During the maneuver, the tanker came closer to the riverbank, causing the vessel to experience bank effect—when a ship’s bow is pushed away from the bank and the stern is pulled toward the bank while transiting in confined waters.

The pilot’s subsequent rudder and engine orders could not overcome the bank effect, and the tanker could not complete the turn without striking the pier.

In addition to bank effect, the Hafnia Amessi was affected by the flood current when the vessel rounded the bend. As the tanker’s bow emerged from the shadow of the east bank, the current acted on the submerged portion of the vessel’s port bow—pushing it away from the bank and further working against the attempted turn.

The NTSB investigated another contact with Pier B in 2022 that was also caused by a pilot maneuvering a tank vessel, Bow Triumph, too close to the bank.

The Bow Triumph and Hafnia Amessi contacts demonstrate the risks associated with bank effect and current. If the Hafnia Amessi had approached the left turn in the relatively open water on its starboard side, the bank effect on the vessel’s port side would have been minimized, and the vessel would have been better positioned to handle the oncoming flood current.

As a result of the Bow Triumph and Hafnia Amessi contacts with Pier B, the Coast Guard Captain of the Port for Charleston issued orders requiring all vessels of 10,000 gross tons or more or with drafts exceeding 25 feet to “employ a tethered two-tug escort while transiting between Pier [B] and Snow Point.”

“Hydrodynamic forces reduce rudder effectiveness (squat and shallow water effect) and yaw the bow away from the closest bank and pull the stern in (bank effect),” the report said. “Shoaling can reduce the water depth in shallow waters, such as channels, below charted or expected, and therefore exacerbate the forces on a vessel. 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. 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.”

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