Probe: Insufficient freeboard, hatch cover caused tug to sink in Hawaii

A missing 20-inch hatch cover was one of the main reasons for a tugboat sinking off Honolulu in January 2015, the National Transportation Safety Board (NTSB) has said. 

Nalani was testing a new autopilot system when it sank in 2,200 feet of water about 1.5 nm off Barbers Point. All 11 people on the tug were saved. There were seven crewmembers aboard — mostly from Panama — plus two owner’s representatives, a pilot and a technician.

The National Transportation Safety Board report, backed up by witness interviews with the Coast Guard, said the pilot saw the boat was flooding and alerted the captain. The boat began heading back to port with following waves breaking over the stern. 

“This direction put the sea swells on the stern and increased the rate of flooding,” the NTSB said in the report. The captain sent a distress call and the crew abandoned ship. Just 20 minutes after the distress signal, the boat sank stern-first.

“The probable cause of the flooding and eventual sinking of the Nalani was the captain’s decision to get underway without sufficient freeboard at the stern and without ensuring proper watertight integrity,” the NTSB investigators wrote. 

Michael Stewart, project manager at Marisco, the yard that did all Nalani’s repair work, told Professional Mariner, “We noticed how low in the water the stern was when the Nalani left the harbor. Normally you would expect freeboard to be at least a foot, but this was about 3 inches.”

According to the NTSB report, “This excessive stern trim resulted from the majority of fuel being loaded in the aft section of the vessel and the water tanks in the forward section being empty.”

Before the vessel left port for the autopilot trial, an owner’s representative told a shipyard worker to cut out the 20-inch cover on the stern deck and replace it with a different type, which was to be bolted on. 

“After the steel plate was cut and removed, the shipyard worker went ashore to drill the new cover, but when he returned about 1435, the Nalani had already departed for the sea trial,” the investigators wrote. The crew had put on a temporary cover, which leaked. “The captain told investigators that he was aware of the unsecured opening but decided to get underway for the sea trial anyway,” the report said.

In a witness interview, the pilot said that as the vessel turned 180 degrees back to port, “I noticed that the back deck of the tug was awash. I asked the captain if this was OK and he said yes. I continued to watch and the stern of the tug was sinking further. Informed captain again and he agreed this was a problem.” 

He told the captain to get the crew on deck in life jackets. The chief engineer came onto the bridge and said the aft peak tank had flooded “but vessel OK,” said the pilot’s statement. Soon after, a list developed and the captain gave the abandon-ship order.

“It is reported that the stern was underwater and then after 10 minutes it started listing to port,” the captain told the Coast Guard in an interview that was translated from Spanish. “In that moment I gave the order to abandon ship and proceeded to turn off the engines and went to the deck with the pilot and help the crew that were still on board. After seeing that all the crew was on the water, I jumped to the water.” 

A Coast Guard analysis of the sinking simulated the forces that could have doomed Nalani.  

“In a static condition without the effects of wind, waves, water on deck or additional flooding, the vessel may have remained afloat,” the Coast Guard analysis stated. “However, in a dynamic environment, any or all of these factors could have led to sinking.”

The Panamanian-flagged tug was owned and operated by Remolcadores de Altura SA. The vessel already had undergone a huge amount of repair and overhaul work during the several months prior to the sinking, and was due to tow two barges to Chile the next day.

The NTSB report said the owner of the boat was a San Francisco company, Vogel Equipment. But the chief executive, Marc Vogel, told Professional Mariner that he had already sold the vessel. This was confirmed by an NTSB spokesman.

While still owned by Vogel, Nalani underwent significant repairs to the hull and decking. A worksheet from the dockyard records dozens of major repairs, including engine work.

By Professional Mariner Staff