Passengers disembark from the Triumph February 14, 2013 in Mobile, Alabama. Getty Images Carnival has canceled 12 cruises on two ships so it can update the vessels' fire-fighting and power systems, the cruise line announced Tuesday.

The changes will be made on the Triumph, which was stranded for five days in the Gulf of Mexico after an engine room fire knocked out onboard power, and the Sunshine, which is undergoing a previously scheduled full-ship makeover that will be extended.

10 of the sailings canceled were scheduled for the Triumph, which operates four- and five-day cruises in the Gulf of Mexico.

The Triumph will re-enter service on June 3, and the Sunshine, which cruises mostly in the Mediterranean, will begin sailing again on May 5.

Passengers who had bought tickets for a canceled cruise will receive a full refund, reimbursement for non-refundable transportation costs, and a 25 percent discount on a future similar cruise.

The company has suffered a spate of bad news recently. The Triumph fire in February was followed by incidents on two more ships in March: Cruises on the Dream and Legend were cut short by ship malfunctions.

On a conference call last week, Carnival executives said the company had increased its spending on regular maintenance, as its fleet of ships ages.

Planned upgrades include enhanced operating redundancies, the ability to run more services on emergency power, and improvements to fire prevention, detection, and suppression systems.

The Triumph and Sunshine are not the only vessels Carnival will work on: The company's statement described the repairs as "the first implementation phase of its fleetwide comprehensive operational review."