美国国家运输安全委员会(National Transportation Safety Board)周三表示，去年在休斯顿航道(Houston ship Channel)，一艘拖船在进行港口辅助机动时速度过快，导致与一艘集装箱船相撞。

拖船George M和集装箱船MSC Aquarius于2022年4月14日相撞，当时拖船正在进行船舶辅助机动，集装箱船正在休斯顿船舶航道向北航行。没有人员伤亡的报告。大约1000加仑的齿轮油从受损的George M号左舷推进装置中释放出来。两艘船的损失总额超过90万美元。

George M号和另一艘拖船正在执行港口辅助操作，将MSC Aquarius号停靠在码头。George M被分配到集装箱船船头的“前导中心”位置。为了接近MSC Aquarius号的船首，拖船必须在集装箱船前面进行船头对船头的机动。相撞时，George M号上的大副正在操作拖船。这是这位大副第一次在“George M”船上轮岗。

当George M号以9.7节的速度通过时，大副操纵拖轮接近了这艘集装箱船。当拖船试图将其缆绳连接到集装箱船时，拖船偏离了中心线。大副试图将拖船驶回中线，但无法恢复位置。大副的操作导致了两艘船的两次碰撞。

大副本可以要求MSC Aquarius的引航员减速，但在被分配到中导位置后，大副没有与引航员沟通。引航员不知道拖船的状况，也不知道需要减速。美国国家运输安全委员会认为，碰撞的可能原因是“George M”号大副试图在拖船和集装箱船以超过港口辅助机动的速度通过时进行艏对艏调整。

造成这次碰撞的原因是George M·的大副缺乏操作拖船的经验。

报告称：“使用方位船尾驱动（ASD）拖船进行船头至船头港口辅助作业时，伤亡风险随着速度的增加而增加。辅助船只船头周围的水动力随着速度呈指数级增加，而拖船操作员可用的备用推进力则减少。”

“执行首对首港口辅助操作的ASD拖船的船东和运营商应该为这些操作设定速度限制。根据设计，不同级别的拖船的速度限制可能有所不同。拖船操作员应在进行这些操作之前，将这些预先确定的速度限制告知他们所协助船只的船长或引航员。”

▲The George M (left) is pictured after the collision and the MSC Aquarius (right) is pictured in September 2022. (Source: U.S. Coast Guard (left) and Osvaldo Traversaro (right))

英文原文

Excessive speed during an advanced harbor-assist maneuver led to a tugboat colliding with a container ship in the Houston Ship Channel last year, the National Transportation Safety Board said Wednesday.

The tugboat George M and container ship MSC Aquarius collided on April 14, 2022, while the tugboat was positioning for a ship-assist maneuver and the container ship was transiting north in the Houston Ship Channel. No injuries were reported. About 1,000 gallons of gear oil were released from the damaged George M’s port propulsion unit. Damages to both vessels totaled more than $900,000.

The George M and another tugboat were performing a harbor-assist operation to dock the MSC Aquarius at the terminal. George M was assigned the “center lead forward” position on the bow of the container ship. To make up to the bow of the MSC Aquarius, the tugboat had to maneuver into position ahead of the container ship, bow-to-bow. The mate on the George M was operating the tugboat at the time of the collision. It was the mate’s first rotation on board the George M’s class of vessel.

In maneuvering the George M to the center forward position, the mate approached the container ship as it was transiting at 9.7 knots. While attempting to connect its line to the container ship, the tugboat moved out of the centerline. The mate attempted to maneuver the tugboat back to the centerline but was unable to regain position. The mate’s attempt resulted in two collisions between the vessels.

The mate could have requested the pilot of the MSC Aquarius to slow, but the mate did not communicate with the pilot after being assigned to the center lead forward position. The pilot was unaware of the status of the tugboat or the need to slow. The NTSB determined the probable cause of the collision was the George M mate’s attempt to make up bow-to-bow while the tugboat and container ship transited at a speed that was excessive for the advanced harbor-assist maneuver.

Contributing to the collision was George M mate’s lack of experience operating the tugboat.

“The risk of a casualty during bow-to-bow harbor-assist operations with azimuthing stern drive (ASD) tugboats increases with increasing speed. Hydrodynamic forces around an assisted vessel’s bow increase exponentially with speed, while the amount of reserve propulsion power available to the tugboat operator decreases,” the report said.

“Owners and operators of ASD tugboats that perform bow-to-bow harbor-assist operations should set speed limits for these maneuvers. These limits may vary for different classes of tugboats based on design. Tugboat operators should communicate these pre-determined speed limits to ship masters or pilots in command of the vessels that they are assisting before engaging in these maneuvers.”

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