According to the National Transportation Safety Board (NTSB), an uncrewed general cargo vessel sank on March 6, 2022, during a towing operation near the Magallanes Bank, approximately 25 nautical miles northwest of Santo Domingo Cay, Bahamas. The incident occurred while the vessel was being relocated under tow. No injuries were reported.
What Happened
On March 3, a towing vessel departed the Port of Miami, initiating a four-day dead ship tow of a general cargo vessel bound for a shipyard in Haiti. The towed vessel had been laid up for two years and was in visibly poor condition due to a lack of maintenance. It was connected astern using a 2-inch wire rope tow line approximately 1,000 feet long, attached to a Spectra bridle and chafing gear routed through deck fittings.
By midnight on March 6, the tow was progressing at 4.2 knots in sea conditions near the operational limits defined in the approved tow plan—winds of 24–30 knots and waves of 7–9 feet. At 0035, the towing vessel’s mate reported hearing a loud noise followed by increased speed, indicating that the towline had parted.
The crew observed that the cargo vessel’s port anchor chain had deployed, and the ship was sitting lower at the stern. Despite rough conditions, they resecured the tow by reconnecting to the remaining portion of the bridle and continued slowly under tow. By sunrise, the towed vessel appeared trimmed further by the stern.
At 07:20, the mate boarded the cargo vessel and discovered the engine room was flooded above the main engine. Attempts to dewater using a portable pump were unsuccessful. By 15:00, the ship began to list to starboard, prompting the crew to prepare for its imminent sinking.
At approximately 15:20, the mate departed the vessel. The towing crew released the full length of the tow wire before cutting it to maintain distance. At 16:20, the ship sank stern first in 3,300 feet of water, taking the towline and bridle.
Why It Happened
The NTSB determined that the probable cause of the incident was uncontrolled flooding of the engine room from an unidentified point below the waterline. Contributing factors included the poor material condition of the vessel, the deployment of the port anchor, and increased hydrodynamic drag from the vessel’s deeper draft. Combined with dynamic loading in heavy seas and high winds, these factors placed excessive stress on the towline system.
Actions Taken
The tow plan had specified operational limits for sea state and wind conditions. While these conditions were approached but not exceeded, the crew followed procedures by attempting to resecure the tow and deploying dewatering equipment—final actions involved safely distancing the towing vessel before the tow was severed.
Lessons Learned
- Vessels scheduled for dead ship tows should undergo thorough condition assessments to identify vulnerabilities, particularly below the waterline.
- Towline arrangements must account for dynamic loads in marginal sea conditions.
- Pre-deployment of emergency equipment, such as dewatering pumps, is critical, but their capacity should match worst-case scenarios.
- Continuous evaluation of vessel condition during tow operations is essential, especially after line failures or unexpected vessel behaviour.
- Operational limits in tow plans should be treated conservatively when the vessel condition is questionable.
Did you subscribe to our Daily newsletter?
It’s Free! Click here to Subscribe!
Source: NTSB
