Unsecured openings in the deck of a towing vessel led to its eventual flooding and sinking off the coast of Puerto Rico are the findings from the National Transportation Safety Board (NTSB).
The towing vessel, Proassist III, suffered flooding in its stern compartments and sank near Puerto Yabucoa, Puerto Rico, on December 24, 2020, while transiting northbound off the coast. The three crewmembers on board were unable to pump out the water and eventually abandoned the vessel. No injuries were reported. The vessel was declared a total loss at $968,000.
Shortly after departing Laguna de las Mareas, Guayama, the Proassist III encountered worsening weather conditions and seas began washing on deck. More than two hours after their departure, the crew noticed the vessel was down by the stern and found about 3 feet of water in the flanking rudder compartment. Roughly 40 minutes after the crew discovered the water and attempted to pump it off, the flanking rudder and steering rudder compartments were filled with water. A post loss examination of the vessel showed openings in the vesselâ€™s watertight bulkheads and a lack of gaskets and securing mechanisms for flush hatches and door openings on the deck.
NTSB investigators did not find any hull structural defects that could have allowed for the significant flooding and concluded a cover for an aft deck opening must not have been in place.
Recently implemented regulations for towing vessels required all openings to be secured when operating offshore. The regulations also require maintaining the watertight and structural integrity of the vessel. However, deficiencies found in the post loss examination of the Proassist III indicated that the vessel was not adequately maintained. The U.S. Coast Guardâ€™s Concentrated Inspection Campaign found three other vessels owned by the Proassist III owner had hull and deck integrity issues, signaling the company did not have an effective maintenance program.
The NTSB determined the probable cause of the sinking of Proassist III was unsecured or open aft deck hatches, which resulted in the flooding of the vesselâ€™s aft compartments from water on deck and progressive flooding to other compartments through openings in watertight bulkheads. Contributing to the flooding of the vessel was the ownerâ€™s lack of an effective hull inspection and maintenance program.
Download the report: NTSB Proassist III Report