Carnival cruises canceled. Ship out of service until June.

The Carnival Triumph, which was crippled by an engine fire in the Gulf of Mexico last month leaving 4,200 people stranded for five days, will be out of service longer than initially expected, Carnival Cruise Lines announced Tuesday.

The ship is now set to return to service June 3, meaning an additional 10 cruises from Galveston, Texas, will be canceled. Guests on the affected voyages will receive a full refund, reimbursement for non-refundable transportation costs, and a 25 percent discount on a future four- to five-day cruise.

Also, the Carnival Sunshine, which is undergoing a scheduled full-ship makeover, will return to service May 5, following the cancellation of two European cruises.

The cruise line is making significant investments to enhance its backup systems and the scope of hotel services that can run on emergency power, and further improve each ship's fire prevention, detection, and suppression systems.

"We sincerely regret canceling these cruises and disrupting our guests' vacation plans," Carnival president and CEO Gerry Cahill said in a release. "We are fully committed to applying the recommendations stemming from our fleet-wide review and to make whatever investments are needed despite the difficult decision to impact people's vacations."

Mike Driscoll, editor of Cruise Week, said Carnival is smart to take the extra time and make the necessary improvements, because it shows the company is taking the recent shipboard problems seriously.

"The cancellations are painful in the short-term, both to Carnival customers and Carnival Corp.'s bottom line, but a very shrewd maneuver in the long-term," Driscoll said. "Carnival is facing increasing scrutiny, not just from media, but from Congress, so they're acting quickly to forestall legislative maneuvers that might require them to make such moves anyway down the line. The view is that it's better to do it on your own, as opposed to having politicians require you to make changes."

Stewart Chiron, an industry expert known as "The Cruise Guy," said the fact that Carnival is making the additional redundancy and fire prevention upgrades to the Sunshine, which was already in dry-dock receiving a $150 million refit, demonstrates that Carnival means to make the improvements fleet-wide.

"This isn't going to take years of discussion and committee," Chiron said. "These changes are going to be implemented immediately, and these are the first two ships to get it. It's actually very encouraging."

In its earnings release last week, the Miami-based company said advance bookings for 2013 are behind the same point from a year ago. The company blamed Europe's economic problems for its inability to raise prices. North American prices are up slightly but those in Europe and Asia are lagging. Passengers in Europe are booking vacations much closer to the date of departure, Carnival said.

But vacationers have been wary about booking cruises ever since the Costa Concordia – also owned by Carnival – sank off the coast of Italy in January 2012. Passengers have returned to the seas, but many needed to be coaxed by deep discounts.

And the Triumph wasn't the only Carnival ship to experience problems this year. The company ended the voyage of the Carnival Dream last week after the ship's backup emergency diesel generator failed, causing problems with elevators and toilets. Instead of allowing the cruise ship to return to Florida, Carnival was forced to charter airplanes to fly home the ship's 4,300 passengers. The Dream's next trip, which was supposed to start Sunday, was canceled.

The company also said that another ship – the Legend – was having mechanical problems and skipped its stop at the Cayman Islands, heading straight to its final port in Tampa, Fla., instead.

Carnival runs cruises under 10 brands including Holland America, Princess, Cunard, and its namesake line.