A dense fog advisory was in effect in Newport until 9 a.m.
The car went into the water near an area called the Travelift pit, the place in the marina where boats are lifted in and out of the water. Among the services the shipyard provides are dockage for luxury yachts and sailboats, as well as services for their owners, such as showers and workout facilities.
Coast Guard Petty Officer Ryan O'Hare earlier said that the car had been in the water for at least several hours. Newport Fire Department Deputy Chief Frank Young said firefighters wearing wetsuits and goggles discovered the women inside the car in the shallow water.
The shipyard is open 24 hours, and a security guard is posted at the entrance at all times.
A spokeswoman for the shipyard referred all questions to police.
Niedowski reported from Providence, R.I.