NTSB: watertight doors – vessel sank after flooding

The National Transportation Safety Board (NTSB) of the United States has published findings from an investigation into the flooding and sinking of a towing vessel.

What happened

A towing vessel was in transit when its stern compartments began flooding. The three crew members aboard attempted to pump out the water but were unsuccessful and subsequently abandoned the vessel. They were rescued, and the towing vessel later sank close inshore. 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.

What went wrong?

Investigation determined that the probable cause of the sinking of the towing vessel was unsecured or open aft deck hatches, which resulted in the flooding of the vessel’s aft compartments from water on deck, leading to progressive flooding of other compartments through openings in watertight bulkheads. Contributing to the flooding of the vessel was the owner’s lack of an effective hull inspection and maintenance program.​

Lessons Learned

The NTSB noted that in the last five years it has investigated five casualties involving towing vessels whose weather decks and openings were in poor condition—leading to flooding and subsequent sinking.

• To protect vessels and the environment, it is good marine practice for owners to conduct regular oversight, inspection and maintenance of hulls, including between drydock periods, regardless of inspection requirements;
• An effective maintenance and hull inspection program should proactively address potential steel wastage, identify hull and watertight integrity deficiencies, and ensure corrosion issues are repaired in a timely manner by permanent means.​

Members may wish to refer to:

• MAIB: Flooding, capsize and foundering of small vessel after issues with towing wires
• USCG: Unexpected heavy weather dangers
• NTSB: Flooding, sinking and loss of tugboat Mangilao