Continuous shuffling machines, which were introduced in cruise ship casinos a few years ago but subsequently pulled from most ships, are now making a comeback with Carnival and Princess cruise lines, according to a new report in the Cruise Casinos Guide.

Continuous shuffling machines (CSMs) are being installed at all the blackjack tables on Carnival Cruise ships and are being installed on half the ships of the Princess fleet, according to Rodney C. Dofort, Vice President Casino Operations for Carnival Corporation.

When using a CSM, the blackjack dealer deals directly out of the machine instead of from a "shoe" that holds eight decks of cards. This eliminates the need for a blackjack dealer to shuffle the entire eight decks after about two-thirds of the cards have been played.

Instead, the dealer inserts discards back into the CSM after every hand, and the shuffler in turn randomly mixes them back into the six decks of cards inside the machine. The play never stops -- which means about 20 percent more hands dealt per hour.

"We find that the use of shufflers is particularly beneficial when a guest has only a brief window of opportunity to play between, for example, dinner and the show because we are able to keep the game in continuous operation for them," said Dofort.

"So far there has been very little comment reported from our guests and the new equipment is proving very reliable," he added.

But many higher-stakes blackjack players do not like CSMs, believing they disrupt the rhythm of the game and result in fewer "runs" -- even though the machines do not, contrary to popular opinion, increase the house edge on a given hand, according to Cruise Casinos Guide.

As a result, few land-based casinos that use the shuffling machines have them on their higher-stakes blackjack tables, and Norwegian Cruise Lines -- which has the CSMs on all of its ships -- uses them at $5 blackjack tables but not at blackjack tables with higher minimums.

"The low limit games get the most of the play, so you obviously get a faster game with the machines," said Jim Green, Vice President of Casino Operations for NCL.

"But the more discerning player is not so keen on them," Green added. "We do not have any plans to ever reach the point where such a person would come on an NCL ship and not get a game without one of those machines. We are not heading in that direction."

Royal Caribbean, which like Carnival installed the CSMs on most of its ships a few years ago only to later pull them out, said it currently uses the shuffling machines only on its older ships that sail three and four day cruises.

"When we first started four or five years ago, we got quite a few comments about them," said Stuart Reading, Acting Director, Casino Operations for Royal Caribbean. "We knew the players didn't like them, so that cemented our decision to pull them out."

Reading said Royal Caribbean has no plans to expand use of the shuffling machines to more of its ships.