“Excessive speed” seen in expensive tugboat collision with containership

George M, seen here in a post-collision photograph, incurred an estimated $750,000 in damage. [Photo: USCG]

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

The vessels in involved were the tugboat George M and the containership MSC Aquarius. The incident occurred on April 14, 2022, when the vessels collided while the tugboat was positioning for a ship-assist maneuver and the containership 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. Damage to the George M was estimated at $750,000; damage to the MSC Aquarius was $183,665.

The George M, owned by Bay-Houston Towing Co. and operated by G & H Towing Company, was built in 2021 by Gulf Island Shipyards in Jennings, La., and was a “30-80” class ASD (azimuthing stern drive) tugboat with a length of 30 meters and bollard pull of 80 tonnes. It was powered by two 3,386-hp Caterpillar diesel engines, each driving a Schottel Z drive.

The MSC Aquarius, owned and operated by Genious Shipping S.A. and managed by Cyprus Sealines Co., was a 983.9-foot lCyprus-flagged containership, built in 2003 by Japan Marine United Corp. in Kure, Japan.

According to the NTSB summary of its full report, the George M and another tugboat were performing a harbor-assist operation to dock the MSC Aquarius at the terminal. The George M was assigned the “center lead forward” position on the bow of the containership. To make up to the bow of the MSC Aquarius, the tugboat had to maneuver into position ahead of the containership, 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 containership as it was transiting at 9.7 knots. While attempting to connect its line to the containership, the tugboat moved out of 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 NTSB says 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 containership transited at a speed that was excessive for the advanced harbor-assist maneuver. Contributing to the collision was the 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.”

As always, there’s much more detail in the full NTSB report — including more details on how the tugboat collided with the containership twice.

“After striking the bow of the MSC Aquarius, the George M continued over to the port side and ahead of the containership,” says the full report. “The mate began working the George M back toward the centerline of the MSC Aquarius, but at the same time the tugboat’s speed slowed, bringing the George M toward the bow of the MSC Aquarius again. According to the mate, he increased speed on the engines to full power and attempted to angle the tug away from the ship, but the tug did not respond quickly. Consequently, the George M collided with the MSC Aquarius again. During the collision, the tugboat’s port Z-drive struck the ship’s bulbous bow, disabling the propulsion unit.

“With the port Z-drive disabled, the George M slid aft along the port side of the MSC Aquarius until it became lodged in the flare of the containership’s bow.”

• Read the full NTSB report