By Tom Stieghorst

Royal Caribbean has begun offering all-inclusive drink packages on 13 ships and plans to make them available on all of its vessels sailing voyages of at least seven nights by early next year.

Passengers can now purchase “Classic” or “Premium” packages. Royal Caribbean has been testing the idea on several ships this year.

The Classic package includes beer and house wines, plus non-alcoholic beverages, for $45 a day. Premium, for $55 a day, adds frozen drinks and cocktails, including premium brands, to the Classic lineup.

Packages must be bought on or before the first day of the cruise and cover every day of the cruise. Also, if one passenger in a cabin buys the package, everyone over 21 in the same cabin must also buy one.

Carnival Cruise Lines began testing a similar package this summer and has it available on a half-dozen ships, while Norwegian Cruise Line has said it is evaluating such a package.

Fans of the idea say it helps them manage their bar bills; opponents say it facilitates excessive drinking.