ANCHORAGE — One man died aboard a sinking Alaska vessel last year in part because he was too large to fit into a survival suit. A second man died after he “froze” and refused to climb out of a wheelhouse onto a deck and toward a lifeboat as the boat listed severely.

The harrowing last minutes on board the Exito about 4 miles north of Unalaska Island in the Aleutian Chain were described in a National Transportation Safety Board accident report that concluded inadequate preparation for emergencies contributed to the men’s deaths two years ago. The report did not identify the men who died or anyone else who was aboard the ship.

Both men were passengers aboard a cargo run between Dutch Harbor, one of the nation’s largest fishing ports, and Akutan, the home of a fish processing plant. A third passenger survived.

The 117-foot Exito was built in 1956 as an oil field vessel in the Gulf of Mexico. It was converted to a crab boat but removed from fishing by a federal buyback program. After 2012, the Exito moved cargo and hauled crab waste from processing plants to an offshore mixing zone.

The NTSB concluded the 60-year-old vessel sank from “progressive flooding” from an undetermined location. The vessel had not been inspected by the Coast Guard since 2003. Though known to leak in its forward space, the ship carried cargo weighing only about 10,000 pounds, far less than it would have carried when it was crab fishing.

The three passengers were contractors who worked for a company conducting refrigeration piping inspections at the Akutan seafood plant. The deckhand gave them a safety briefing that included instructions on how to use an immersion suit, a dry suit that covers users from head to toe and protects them from hypothermia in cold water. They were told to head for the wheelhouse, the highest point on the boat, if they heard the emergency alarm.

Immersion suits are designed to be put on in less than 2 minutes. None of the contractors tried them on, and if they had, they may have learned that standard adult suits, made for people weighing up to 330 pounds (150 kilograms), were too small for them, the NTSB said in its analysis.

The Exito left Dutch Harbor shortly before 7 p.m. on Dec. 6, 2016. Sometime after 9 p.m., in 10-foot (3-meter) seas, the Exito experienced a roll and did not right itself, listing 2-3 degrees to starboard. The skipper soon called the owner and said he was turning back to Dutch Harbor.

Cargo pallets shifted on the open deck. Waves washed across the deck from the starboard side.

The contractors started donning their immersion suits in the galley below the wheelhouse. The captain sent out distress calls.

When the captain realized none of the contractors had climbed to the wheelhouse, he went down to gather them.

One was suited up. One needed assistance but could not pull the suit’s zipper up the final few inches. He also said he could not swim.

The third had even more difficulty getting into the suit. He got the hood on but could only close the zipper to the middle of his chest. The boat by this time was listing 7-10 degrees.

When the captain said they had to get the wheelhouse, the third contractor replied, “I can’t do this.”

The captain told investigators he tried dragging the man to the stairs, which by now required climbing like a ladder. The captain scrambled to the wheelhouse and told the contractor to follow.

At the wheelhouse, the deckhand and a contractor tried to help the second contractor out of the wheelhouse and onto the deck, toward a life raft, but he kept repeating, “I can’t.” They tried pushing him out but he braced himself against the door.

The captain helped the crewman push the life raft canister overboard and turned back to the wheelhouse. The third contractor had made it to a landing on the steps leading to the wheelhouse. The second contractor gripped a handrail at the top of the stairs. As the captain tried to re-enter the wheelhouse, the boat went under.

The deckhand, the captain and the first contractor swam to the life raft. A nearby fishing boat spotted their flares and picked up the survivors 10:44 p.m. in 12-foot (3.6-meter) waves.

The NTSB released its report last month. The Coast Guard also is preparing a report on the sinking.