NTSB Report Finds Oily Rags Caused M/Y Pegasus Fire

29 June 2023 By Aileen Mack
M/Y Pegasus fire
Credit: Gig Harbor Police Department

Associate Editor Aileen Mack joined Dockwalk in July 2018. She is a graduate of the University of Florida with a bachelor’s degree in journalism. If she’s not at a concert or coffee shop, she is lost in a book, movie or a YouTube rabbit hole. Email Aileen at

On July 15, 2022, M/Y Pegasus caught fire in Gig Harbor, Washington. Fortunately, no one was on board at the time, but the fire burned for about an hour before it was reported so by the time firefighters arrived, the fire had engulfed the aft section of the 80-foot yacht. The National Transportation Safety Board (NTSB) determined the probable cause of the fire was “spontaneous combustion due to the self-heating of used oil-soaked rags that had been improperly disposed of on the aft deck of the vessel,” according to the accident report.

Rags soaked with oil-based finishes pose a fire hazard if stored improperly because they generate heat as they dry. If the heat isn’t released into the air or allowed to escape, it creates a high risk for spontaneous combustion — the heat builds up and then causes a fire. The report says, “To prevent a fire, users of oil-based products (or any chemical product) should carefully follow the manufacturer’s instructions for cleanup and disposal of rags, steel wool, brushes, and other applicators.”

The yacht was moored at Peninsula Yacht Basin, which had no marina staff or personnel on the docks overnight. Security cameras first captured smoke and flames on the aft at 2:04 a.m. and the fire burned for 45 minutes before intensifying and spreading forward. Then at 3:02 a.m., a bystander noticed the fire and called 911, police arrived at 3:16 a.m., and firefighters arrived four minutes later. Gig Harbor Police officers found the aft half of the yacht completely engulfed in flames, and firefighting started at 3:32 a.m. from the floating docks on the starboard side.

While firefighters reduced some flames, the fire was persistent and continued to flare up. “At 4:14 a.m., the stern of the Pegasus sank with the bow rising out of the water. The bow then slowly settled as the vessel continued to take on water,” the report states. “The last of the fire was extinguished at 4:31 a.m., when the main deck cabin was inundated with seawater.”

The exterior of the stern, swim deck, transom, and aft deck sustained significant fire damage, and the fly bridge collapsed onto the salon and galley, plus combustible materials in the salon and galley were consumed by the flames, according to the report. M/Y Pegasus was a total loss, and a docked vessel nearby suffered minor damage.

Courtesy of owner of M/Y Pegasus

The yacht’s owner told NTSB he believed the cause of the fire was fireworks that landed on the vessel, but marina security camera footage showed no activity around the vessel before the fire. There was no evidence that the fire was caused by an electrical system failure or mechanical issue.

He also told investigators that he and a crewmember had been refinishing wood surfaces on the yacht using a teak oil finish on the day before the fire. They applied teak oil to surfaces with a brush and wiped off excess oil using microfiber towels. The crewmember stated that after finishing the work, he wrapped the used towels in new towels, placed them in a plastic bag, and left the bag under the wood table on the yacht’s aft deck. Then he and the owner left the yacht between 4 and 5 p.m.

The oil finish they used included a warning that “Rags, steel wool, or waste soaked with WATCO® teak oil may spontaneously catch fire if improperly discarded. Immediately after each use, place rags, steel wool, or waste in a sealed water-filled metal container.” The product contains raw linseed oil, a substance known to be a risk for self-heating and spontaneous combustion when soaked in rags.

Like the 2012 fire on board passenger vessel Safari Spirit, the NTSB found that rags used to apply and clean up the oil from the teak wood finish were laid across rails to dry and the fire was accelerated by the flammable materials stored on the main deck aft.

In that report, NTSB noted, “Self-heating is a process in which heat is created within a material through a biological or chemical process and without the application of an external heat source. If self-heating increases the temperature of the material above its ignition point with sufficient oxygen present, self-ignition can occur. Sufficient air must be present to sustain the combustion reaction, but not so much air that the heat is dissipated.”

The Pierce County fire marshal determined a probable cause that the fire was caused by the improper disposal of the soiled rags, resulting in spontaneous combustion, and the table and bench on the aft deck were the first things to catch on fire after the rags. The report said, “Energy released from these furniture items would be adequate to involve the vessel’s construction components and propagate fire advancement.”

The cause of the fire was classified as “accidental.” To read the full NTSB report, click here.


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