Beyond Seaworthiness: Vessel Size, Port Preparedness and Emerging Marine Risks
On 26 March 2024, the 984-foot-long Singapore-flagged containership Dali – lost electrical power, propulsion, and steering while departing Baltimore Harbour and struck a support pier of the Francis Scott Key Bridge. The collision caused a major section of the bridge to collapse into the river. Six highway maintenance workers on the bridge lost their lives, one worker was seriously injured, and one inspector escaped unharmed. Among the 23 people aboard the vessel, one sustained a minor injury. Damage to the vessel exceeded US$18 million, while the bridge replacement cost is estimated at US$4.3–5.2 billion. On its outbound passage from Baltimore Harbour, the Dali suffered a complete loss of electrical power, propulsion, and steering control and subsequently struck Pier 17, the southern pier supporting the central span of the Francis Scott Key Bridge.
On March 26, shortly after departing Seagirt Marine Terminal in the Port of Baltimore, the Dali suffered two electrical blackouts. Investigators found that the first blackout was triggered when Wire 1, a signal wire within the vessel’s main switchboard, became electrically disconnected from its terminal block. This caused a high-voltage breaker to trip, interrupting power to the step-down transformer and resulting in a low-voltage blackout.
The Marine Investigation Report MIR-25-40- discusses the National Transportation Safety Board’s (NTSB) investigation of the March 26, 2024, contact of the containership Dali with the Francis Scott Key Bridge and subsequent bridge collapse near Baltimore, Maryland. Following safety Issues were identified in this report including
- Incorrect wire labelling made it difficult to properly connect wires to terminal blocks.
- No clear inspection guidelines for checking electrical terminal connections.
- Machinery and electrical systems were not adequately designed to quickly restore propulsion, steering, and power after a blackout.
- Emergency communication systems were inadequate, making it difficult to warn motorists and bridge workers during emergencies.
- Marine safety management standards were insufficient to ensure safe vessel operations.
- Voyage Data Recorder (VDR) software standards were inadequate, limiting the usefulness of recorded data during investigations.
- Larger sizes of ships and heavier traffic have increased risks in U.S. ports.
- Many bridges over navigable waterways are vulnerable to collisions from large ocean-going vessels.
In essence, the findings point to weaknesses in electrical systems, emergency preparedness, safety management, data recording standards, growing maritime traffic, burgeoning ship sizes and bridge protection measures.
The root cause was traced to improper wire-label banding. A heat-shrunk identification sleeve covered the ferrule’s insulated collar, increasing its diameter and preventing the wire from being fully seated in the terminal block. As a result, Wire 1 was vulnerable to loosening and eventual disconnection, which initiated the blackout sequence.
The report concluded that the use of infrared thermal imaging—a diagnostic technique capable of detecting hidden electrical faults and overheating components that are not visible during routine visual inspections—could have helped identify the loose Wire 1 connection in the Dali’s high-voltage switchboard. Had this technology been incorporated into the vessel’s preventive maintenance program, the defect may have been detected and rectified before it contributed to the electrical failure. The low-voltage bus supplied power to the low-voltage switchboard, which in turn powered the vessel’s lighting and essential equipment such as the steering gear pumps, fuel oil flushing pump, and main engine cooling water pumps.
The report found that the loss of power to the low-voltage bus caused the initial underway blackout, resulting in the shutdown of vessel lighting and critical machinery, including the main engine cooling water pump and steering gear pumps. This led to a loss of both propulsion and steering.
The report based on investigation found four safety issues that did not cause the initial blackout but affected the vessel’s ability to restore propulsion, steering, and electrical power after the blackout:
- The main engine was configured to automatically shut down when cooling water pressure became too low.
- A flushing pump was being used as a fuel service pump for the diesel generators.
- The high-voltage breakers of the low-voltage step-down transformer were operating in Manual mode instead of Automatic mode.
- The position of the emergency diesel generator’s radiator dampers affected its ability to start properly.
Although these issues were not responsible for the initial blackout, they reduced the vessel’s resilience and complicated recovery efforts afterward.
Emerging Risk Concerns –
The report highlighted a few key concerns like increase vessel size and carrying capacity.
- Increasing Vessel Sizes and Traffic Density- When the Key Bridge opened in 1977, the largest container ships were about 700 feet long. Today, container ships are much larger. For example, the Dali was nearly 1,000 feet long and weighed over 112,000 metric tons, while some modern container ships exceed 1,300 feet in length.
- Ship carrying capacity has also increased dramatically. In the 1950s, container ships typically carried only 500–800 TEUs (twenty-foot equivalent units, the standard measure of container capacity). Modern vessels can carry more than 20,000 TEUs, representing an increase of over 3,000%.
In short, today’s container ships are far larger and can carry many times more cargo than those operating when the Key Bridge was built.
The trend toward increasingly larger vessels present new challenges for port preparedness and infrastructure resilience. Ensuring the safe accommodation of such vessels while protecting critical and potentially vulnerable infrastructure has become a key concern for port authorities and policymakers. The operational, safety, and infrastructural implications of larger vessels constitute an emerging area of study that requires detailed evaluation and strategic planning.
Marine underwriters need to closely monitor these emerging developments, as they have the potential to significantly influence risk exposure, underwriting practices, policy terms, and loss severity. In marine insurance, seaworthiness refers to the fitness of a vessel to safely undertake the voyage or service for which it is intended. It is not merely about whether the ship can float; it encompasses the vessel’s overall capability to face the ordinary perils of the intended voyage. The size can be considered an aspect of a vessel’s fitness for the intended voyage, and therefore relevant to seaworthiness, although it is not traditionally classified as a separate element of seaworthiness in the same way as hull integrity, machinery, or crew competence.
The classic legal test of seaworthiness asks whether the vessel is reasonably fit to encounter the ordinary perils of the contemplated voyage. If the vessel’s size, draft, air draft, beam, or maneuvering characteristics make it unsuitable for the ports, channels, bridges, or waterways it must navigate, the vessel may be regarded as unfit for that particular voyage. For example, an ultra-large container vessels (ULCVs) exceeding 20,000 TEU require wider turning basins, deeper channels, more powerful tugs, and specialized pilotage. Sending such a vessel to a port unable to safely accommodate it may indicate that the voyage has not been properly planned.
Authored by:
Prof(Dr) Abhijit K. Chattoraj – Chartered Insurer
