An open watertight door caused the partial sinking last summer of Lovebug, a 122-foot yacht, in the Chesapeake Bay near southern Anne Arundel County, the National Transportation Safety Board’s investigation found.

NTSB investigators determined that a door located between Lovebug’s garage compartment for holding watercraft and its engine room was left open, allowing the yacht to take on water, tip over and partially sink in 12 feet of water near the mouth of the West River on July 27, 2024.

“Failure to maintain the integrity of a vessel’s watertight envelope can reduce a vessel’s overall stability should unintentional flooding occur,” investigators wrote in their report about the sinking. “If minor flooding goes unnoticed, the gradual reduction in initial stability may go unnoticed by operator.”

According to the NTSB, the partial sinking caused about $8 million in damage.

Investigators with the federal agency, which analyzes transportation incidents with an eye toward improving future safety and not assigning blame, interviewed one of the yacht’s owners, its captain and three crew members.

“Nobody on board observed flooding in the short time before they abandoned the vessel,” the NTSB report said.

The co-owner, captain and crew jumped from the sinking yacht and were rescued by boaters, investigators said. One crew member reported a minor injury.

Lovebug remained in the water for 16 days, with authorities containing an oil spill while salvage crews devised a plan to raise the yacht and tow it to a shipyard in Dorchester, New Jersey.