Katherine Slover was sitting in her car with her husband at the White’s Ferry landing in Montgomery County Friday afternoon when she saw something odd. The underwater cable that guides the ferry across the Potomac River between Maryland and Virginia had snapped, she said, “shot up in the air and smacked down on the water, and water shot up in the air. It was beautiful.”

Then the ferry took a right and started heading downstream.

After a brief discussion with her husband about whether this was standard navigation for the ferry, Slover hopped out of the car and began running along the bank, while passengers watched and the boat captain yelled frantically for help.

Slover navigated her own perilous route to the river’s edge, and with instruction (and ropes) from the captain tied the boat to several trees before it floated off toward Washington. Though 12 cars and about 20 passengers were aboard the ferry, no one was hurt and the ferry was back in operation later Friday night, White’s Ferry general manager Matt Swensen said.

By the time Montgomery County Fire and Rescue boats arrived, the passengers had all reached shore, with the help of Slover and others. “We’ve got to get her an application,” fire spokesman Pete Piringer said, “and have her come work for us.”

“It was exciting,” Slover, 49, of Potomac, Maryland, said Saturday. She had been planning to take the ferry over to Leesburg, Virginia, from its Maryland port of Dickerson. “The current was going quickly and trying to swing the bow around, and I barely got the rope around the tree in time, with my shaking hands.”

White’s Ferry, in operation since 1782, is the last ferry operating on the Potomac and can carry up to 24 cars, its owners say. On Friday it was making its four-minute journey from Loudoun to Montgomery when the guiding cable snapped around 2:45 p.m., Piringer said.

Slover estimated the boat was midway across the river when it took its sudden detour. As she ran along the river, she could hear the captain calling for help. “He was frantic,” Slover said. “People were watching the ferry go downstream. It was unbelievable. I just started chasing it.”