NTSB finds failure to heed severe weather warning led to fatal sinking of Missouri duck boat

Stretch Duck 7 after it was recovered from the waters of Table Rock Lake near Branson, Missouri, following its sinking during a heavy-winds storm on July 19, 2018 (Photo: NTSB/Brian Young)

The US National Transportation Safety Board (NTSB) said during a public board meeting held earlier this week that the continued operation of the amphibious passenger vessel Stretch Duck 7 during severe weather led to the fatal sinking of the vessel on Table Rock Lake, Missouri, on July 19, 2018.

The modified World War II-era DUKW amphibious passenger vessel, operated by Ripley Entertainment, sank in bad weather on Table Rock Lake near Branson, Missouri.

The vessel had 29 passengers and two crewmembers aboard for a tour. One crewmember and 16 passengers died in the accident.

Ripley subsidiary Ride the Ducks of Branson continued to operate waterborne tours even after a severe thunderstorm warning had been issued. This exposed the vessel to a warm-weather event known as a derecho, which resulted in waves flooding through a non-weathertight air intake hatch on the bow and caused the vessel to sink, the NTSB determined.

Contributing to the duck boat’s sinking was the US Coast Guard’s failure to require sufficient reserve buoyancy in amphibious vessels. NTSB investigators found that the accident vessel was originally constructed with a low freeboard, an open hull, and no subdivision or flotation, resulting in a design without adequate reserve buoyancy.

Additionally, the NTSB cited previous inaction to address emergency egress on amphibious passenger vessels with fixed canopies which impeded passenger escape from Stretch Duck 7.

In their investigation, NTSB investigators documented that the National Weather Service had issued a severe thunderstorm watch for the area several hours before the sinking. That watch was followed by a severe thunderstorm warning one minute before Stretch Duck 7 departed the shoreside boarding facility about nine kilometres from the lake where the tours began and ended.

Investigators noted three other company vessels also entered the lake after the severe thunderstorm warning was issued.

The NTSB said the fixed canopy of Stretch Duck 7 contributed to the severity of the accident as the canopy’s design impeded passenger egress as the vessel took on water and sank. When the vessel sank, the closed starboard-side curtain aboard the vessel impeded the passengers’ escape and likely resulted in additional fatalities.

The NTSB issued six safety recommendations with three recommendations issued to the Ripley Entertainment and three recommendations to the US Coast Guard. These recommendations address safety issues including company oversight, engine compartment ventilation closures, reserve buoyancy, survivability, weather training for mariners, and coast guard guidance.

The NTSB issued two safety recommendations on November 13, 2019, calling for sufficient reserve buoyancy and improved emergency egress on DUKW amphibious passenger vessels.

The final report for the investigation is expected to be published in the next few weeks.

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