Open aft deck hatches probably led to sinking of 71-year-old towing vessel, says NTSB

Towing vessel Proassist III was transiting the Caribbean Sea on December 24th 2020, some three miles off the coast, near Puerto Yabucoa, Puerto Rico, when its stern compartments began flooding.

The three crewmembers aboard attempted to pump out the water but were unsuccessful and subsequently abandoned the vessel. They were rescued by a responding Good Samaritan vessel, and the Proassist III later sank about 0.25 miles from shore. No injuries were reported. An oil sheen was visible after the vessel sank. The vessel was later recovered but was considered a constructive total loss, valued at $968,000.

The US National Transport Safety Board (NTSB) concluded that open after deck hatches probably led to the sinking of the vessel.

The NTSB noted that the Proassist III was last drydocked for examination and maintenance in 2013. The owner had scheduled a drydock period for the vessel in June 2021, during which he planned a survey to measure the thickness of the hull plating.

The owner arranged a condition and valuation survey on September 24th 2015. Recommendations included renewing deck hatches and adjusting the portside aft quick-acting door to achieve watertight integrity.

Unsecured openings in the deck of a towing vessel led to its flooding and sinking, the NTSB said.  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 three 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 vessel’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.

Deficiencies found in the post loss examination of the Proassist III indicated that the vessel was not adequately maintained.

The US Coast Guard’s Concentrated Inspection Campaign found three other vessels owned by the Proassist III owner had hull and deck integrity issues, signalling that the company did not have an effective maintenance programme.

“An effective maintenance and hull inspection program would have proactively sought to minimize the wastage of steel on the Proassist III (and other company vessels) and made any corrosion issues easier to identify and flag for repair,” the report said.