The Ole Betts Sea, a Gulf of Mexico shrimper operating out of Fort Myers Beach, Fla., left port on March 13, 2018, and headed out to a spot about 18 miles northeast of the island of Garden Key in the Dry Tortugas.
It was the third trip since the 67-foot fiberglass shrimper ended a three-month layup where a refrigeration unit with a 10-hp compressor was installed and the 40-kW generator and its Detroit 371was serviced.
Prior to leaving on March 13, the captain performed a pre-departure check of the boat and made sure the items on a post-voyage work list, submitted after the previous trip, had been attended to. About two years prior to that, the shrimper’s 360-hp Caterpillar 3408 main engine got a complete overhaul. The generator’s Detroit 371 received a new head and piston liners within the previous year. On the grounds and before starting a new day of fishing, the captain checked the main engine’s oil and water levels and the batteries for water.
It seems like a fair amount of attention was paid to the engine room machinery and there shouldn’t have been major problems. But that’s not how things worked out. About 6:15 a.n. on March 18, as the Ole Betts Sea was idling along at 2.5 knots on the last set of the day, a “small boom” sounded from the engine room. A minute later the boat starting shaking and “small boom like noises” continued to come from the engine room. The captain couldn’t move the throttle to neutral to stop the boat.
Attempting to get into the engine room, the captain encountered “thick, grayish smoke” when he opened the main deck’s engine room door. That’s when he called a nearby boat saying the Ole Betts Sea was on fire. (The Ole Betts Sea did not have a fixed fire fighting system for the engine room.)
Three minutes later the shaking stopped, the lights went out but the Cat kept turning and the Ole Betts Sea kept plowing forward. In the meantime, the crew donned life jackets and the captain tried to slow the Ole Betts Sea down to launch a life raft by dropping the anchor and the trawls.
Then there was a large explosion. That stopped the Ole Betts Sea progress while sending out thick, black smoke. One crewman launched the life raft with himself and the boat’s dog in it. Shortly the captain and the remaining crewman joined them. At 0740 the fishing boat Sea King took the Ole Betts Sea’s crew aboard.
The fire continued to burn until 9:10 p.m. when there was another explosion and the 36-year-old shrimper sank in about 100 feet of water.
As the Ole Betts Sea was not salvaged the exact cause of the fire could not be ascertained but based on the accident investigation by the National Transportation Safety Board, the likely cause for the “boom”, heavy smoke, explosion and fire could be determined.
The initial boom was attributed to the main engine, generator’s engine or propulsion shafting. Since the shaking stopped before the Ole Betts Sea stopped going forward it’s believed the shaking was due to a failure in the generator’s diesel. The large boom and thick black smoke indicated a fuel fire fed by diesel oil from a failed fuel line.
Summing it up, the NTSB determined the “probable cause of the fire and sinking of fishing vessel Ole Betts Sea was a mechanical failure of the generator’s diesel engine, which led to a fuel-fed fire that burned out of control.
The NTSB also notes that the Ole Betts Sea had “no remote emergency cut-off valves for fuel and lube oil systems outside the engine room, and thus fuel to the fire could not be stopped and the vessel was eventually consumed by the flames.”