Cause of Tug-Tanker Accident in Corpus Christi Ship Channel Revealed

The National Transportation Safety Board has identified that speed and hydrodynamic forces were contributing factors in an incident where a tugboat and a tanker collided in the Corpus Christi Ship Channel last year.

On January 22, 2023, the tugboat Mark E Kuebler and the tanker Nisalah were involved in a collision near Ingleside, Texas, which resulted in nearly $7 million in damages to both ships. Thankfully, there were no injuries reported.

According to the NTSB's findings, the tugboat was overpowered by the hydrodynamic forces generated by the larger tanker. The report highlighted the necessity for smaller vessels to maintain a safe distance from larger ships or possess sufficient reserve power to overcome hydrodynamic forces and prevent being drawn in. This advice is especially pertinent for tugboats engaged in harbor-assist operations.

The incident occurred as the Mark E Kuebler, alongside four other tugboats, was aiding the docking of the Nisalah. Positioned at the tanker's starboard quarter, the tug's mate attempted a maneuver to turn and move stern-first to their designated location. Unfortunately, during this maneuver, the tug was pulled toward the tanker, leading to a collision. The NTSB concluded that the tugboat did not have adequate reserve power to counter the hydrodynamic effects, exacerbated by the speed of the movement.

The NTSB has advised that operators of Z-drive tugboats set specific speed limits for complex maneuvers, including stern-first approaches, noting that "These limits may vary for different classes of tugboats based on design. Tugboat operators should communicate these limits to ship masters or pilots in command of the vessels that they are assisting before engaging in these maneuvers."

Following the collision, the tugboat's operating company introduced a policy that restricts the speed of stern-first approaches to assisted vessels to 7 knots or less, in an effort to prevent similar incidents.