(4:00 p.m. EST) -- Carnival Cruise Lines' Carnival Destiny has altered the itinerary of its five-day cruise, which departed Miami on January 21, due to technical problems with its stern thrusters.

Rather than call on Grand Turk and Half Moon Cay as originally scheduled, the ship will instead stop in Key West and Freeport, Bahamas. Neither of the original ports has the tug boats needed to assist the ship in the absence of its stern thrusters.

A stern thruster is a propulsion device that makes ships more maneuverable, especially during docking as they allow the captain to turn the ship to port or starboard without also moving forward.

Passengers and crew are in no danger as all of the ship's safety systems and hotel services are functioning normally, a Carnival spokesman said.

The repair work on the stern thruster is already underway, the spokesman added. "We are hopeful that the repair will be completed and the scheduled itinerary will be operated for the next cruise which departs from Miami on Saturday."

Passengers who chose to continue with the sailing received a $50 per person onboard credit. Passengers also had the option to cancel and receive a full refund.

Carnival Destiny returns to Miami on January 26.

--by Dori Saltzman, News Editor