A Charlestown man has been charged in a nightmarish Boston Harbor pleasure cruise that left a young woman maimed by a propeller and the drunken operator of the “Naut Guilty” in handcuffs, authorities said.

“Her arm was severed just below shoulder,” Coast Guard Petty Officer Lanola Stone said.

The woman, who apparently had fallen overboard, also suffered injuries to her abdomen and face, Stone said.

Boston police said today the operator of the boat, who has been charged with operating under the influence, is Benjamin Urbelis, 33, of Charlestown. He is expected to be arraigned tomorrow at Boston Municipal Court, said BPD spokeswoman Rachel McGuire.

The Coast Guard responded to a call from the “Naut Guilty” at about 7:45 p.m. that a person had fallen overboard and lost her arm, Stone said. A Coast Guard response boat was in the area, arrived on scene swiftly and Coast Guardsmen applied a tourniquet until she was transferred to the Boston Fire Department’s Marine 1 and rushed to shore, Stone said.

Speaking as detectives scoured the deck of the “Naut Guilty” at the docks of the Charlestown Navy Yard, Boston police Capt. Timothy Connolly said the woman is “approximately 19 years old” and “received significant injuries due to possibly hitting the propeller.” The operator of the boat was arrested by the Massachusetts Environmental Police on a charge of operating a boat while under the influence, state police spokesman David Procopio confirmed.

The unidentified victim, who fell overboard near Spectacle Island, was rushed by Boston EMS to Massachusetts General Hospital, Boston Fire Department spokesman Steve MacDonald said. She was in critical condition last night, Connolly said.

There were 13 people aboard the boat at the time of the accident, Connolly said.

Passengers were individually questioned by police at the Charlestown dock where the boat was being inspected last night. They left, many of them sobbing and still wearing trunks and bikinis, without commenting after officers finished the interviews.

Connolly said several passengers had jumped into the water to save the victim.

The somber operator of the 29-foot “Naut Guilty,” barefoot and wearing board shorts on the dock, was read his rights by Environmental Police, who lent him an orange police jacket.

The cause is under investigation, Stone said, with Massachusetts State Police taking the lead on the probe.