By Tom Stieghorst

Royal Caribbean International’s Allure of the Seas has developed a propulsion problem that is slowing the world’s largest cruise ship. The line is considering an early drydock.

Allure, which debuted in 2010, would normally be drydocked in 2015, but Royal Caribbean Cruises Ltd. Chairman Richard Fain said that schedule may be accelerated.

“We’re considering it, sure,” Fain said while onboard Vision of the Seas for a one-night cruise to display its recent renovations to travel agents. “We’re in the process of trying to assess [whether] we move up the drydock, and if it makes sense we will.”

One option would be to give Allure the 2014 drydock slot reserved for sister ship Oasis of the Seas, and push off the Oasis drydock by a year.

The unspecified propulsion issue developed about three weeks ago. Allure can still complete its weeklong itineraries, but the slower speed means that Royal Caribbean has had to shorten its port stay in Nassau, and some excursions have been canceled. It is also arriving late in the next port of call in St. Thomas.

Fain said the design of the Oasis-class ships, which has three podded propulsion motors instead of two, gives it better resilience when one of the units malfunctions.