On August 7, 2022, at 1625 local time, the tugboat CC Portland grounded outside the Corpus Christi Ship Channel, near Ingleside, Texas, while repositioning to secure a tow line on the bow of the inbound liquefied natural gas carrier LNG Fukurokuju. No injuries were reported by the five crewmembers aboard the CC Portland or the 27 crewmembers aboard the LNG Fukurokuju. An estimated 4–5 gallons of diesel fuel were released from a hull breach on the tugboat. Damage to the CC Portland was estimated at $1.3 million.
We determined that the probable cause of the grounding of the CC Portland was the mate’s attempt to make up bow to bow with a liquefied natural gas carrier while the tugboat and liquefied natural gas carrier transited at a speed that was excessive for the advanced harbor-assist maneuver. Contributing to the casualty was the lack of a company policy regarding maximum allowable speed for bow assist maneuvers.
Speed During Bow-to-bow Harbor-assist Operations
The National Transportation Safety Board has previously noted the effect of speed on bow-to-bow harbor-assist operations in other investigations. The risk of a casualty during these 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. Therefore, 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 pilots and ship masters in command of the vessels that they are assisting before engaging in these maneuvers.
