Electrical fault caused the fire on Best Revenge 5 says NTSB report

Image credit: Sailing Directions
Image credit: Sailing Directions

The NTSB has issued its investigation report on the fire onboard sailing boat ‘Best Revenge 5’, while it was docked at a marina pier at Inner Harbor in Falmouth, Massachusetts, in July 2017.

At about 0130 on 11 July 2017, the ‘Best Revenge 5’ caught fire while docked at a marina pier in Falmouth Inner Harbor. The vessel’s two crew members escaped the burning vessel and attempted to fight the fire but could not contain it. Local firefighters later extinguished it.

One crew member sustained second and third degree burns to the arms, hands, and feet. An oil sheen was observed in the immediate vicinity of the vessel after the fire but was contained by a floating boom.

Damage to the Best Revenge 5 (which was declared a constructive total loss), to a vessel docked next to it, and to the pier totalled an estimated $1,508,000.

Probable cause
The National Transportation Safety Board determines that the probable cause of the fire aboard the uninspected sailing vessel Best Revenge 5 and on its pier was an electrical fault in an accommodation space on the vessel.

Analysis
After the fire, marina personnel reported that the circuit breaker powering the dock pedestal from shore was in the “tripped” position (electrically disconnected as a protection measure) and that the two shore power circuit breakers onboard the vessel (fed by cables from the pedestal) were undamaged and tripped to the “off” position as well. They concluded that the vessel “may have been [electrically] powered at the time of the fire.”

The fire originated on the port side of the vessel; specifically, in the area between the port side lavatory, aft stateroom closet, and port side hull, in the area of the shore power pedestal. The only potential ignition sources identified within the area of origin were the shore power pedestal, electrical conductors/ components in the lavatory, aft-port stateroom closet, and area above the aft port lavatory/shower area. The only fuels identified were the fiberglass hull, insulation, and ordinary combustibles within the area of origin. The report noted that both equipment and conductors that may have been affected by the lightning strike (which occurred a month earlier in Bermuda) were “located in the general origin area of the fire.

The report concluded that equipment or conductor failure “due to lightning damage cannot be eliminated as a possible cause of the fire.” Similarly, the shore power pedestal “cannot be eliminated as a cause of the fire” due to several missing components that were unable to be examined. Ultimately, a specific cause of the fire could not be identified “due to multiple ignition scenarios that cannot be eliminated.”

If the shore power pedestal was the source of the fire, it would have had to first have an electrical fault resulting in ignition of the pedestal’s wire insulation and plastic casing. The ensuing pedestal fire would have had to reach a sufficient intensity to ignite the vessel’s paint, fiberglass, and resin on the portside hull through direct flame impingement or radiant heat.

Burn marks on the dock around the power pedestal, however, did not indicate that the pedestal was fully engulfed in fire on all sides. Additionally, the damaged remnants of the power pedestal indicated an uneven burn with the areas farthest away from the boat less affected by the fire.

Read the report in full: NTSB-Fire-aboard-Sailing-Vessel-Best-Revenge-5

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