Whelan called an ambulance to the ferry when she feared she was having a seizure, but she cast off from the pontoon when police arrived, the court heard.
"I'm Jack Sparrow," Whelan allegedly shouted to police, referencing the character from the popular "Pirates of the Caribbean" film series.
The theft set off a chase lasting for more than an hour involving police, the coast guard and the local lifeboat service. The ferry sustained about $2,430 worth of damage from colliding with two other vessels during the chase.
Ashley Lane, operations manager for Paignton Pleasure Cruises, said the incident could have been far worse.
"The fact is that, had circumstances been different tide-wise, it could have been serious," Lane said. "She could have seriously been injured had it gone out of the river."
