An engine room fire incapacitates a 3,000-passenger ship miles from port. Reports surface that the "emergency generator power" now supplying the ship excludes working toilets or showers. Tugs are dispatched to push, pull and prod the ship back to land in a multi-day effort. Meanwhile, resupply missions are coordinated.

Foghorn just go off?

What happened in November 2010 on Carnival Splendor unfolded once more aboard Carnival Triumph, now being coaxed by tugs to Mobile after an engine room fire left it dead in the water.

It also happened on Costa Allegra last March. Ditto for Azamara Quest in April, though propulsion was restored after a day in that case. Before that, it was the same story in April 2011 for Mexican cruise ship Ocean Star Pacific. There were certainly significant variations in each event. The results, however, were the same. Other ships, including Royal Caribbean's Allure of the Seas and Cunard's Queen Mary 2, have had (far less damaging) fires in the last year.

Though that quickly conjured list might make it hard to believe, debilitating cruise ship fires are still rare. Instead of food lines, stifling heat and lack of toilets, 99.9 percent of the nearly 20 million who cruise annually get to focus on main dining room attire, deck chair hogging and daytrips to Cozumel. In the recent incidents, the fires were snuffed, confined to the engine rooms. With the exception of the Quest incident, no one was injured (five Quest crew were hurt, one seriously). Passengers, experiencing the most memorable cruise of their lives, managed to soldier through under deplorable circumstances.

But it's enormously troubling. An engine room fire that's contained relatively quickly manages to TKO the sewage systems and A/C? The ship requires a tug's assistance to move a nautical inch?

The International Maritime Organization, the United Nations body charged with overseeing at-sea safety, is aware of the problem -- and has been for years. As cruise ships balloon to floating-city size, new survivability measures have become necessary. A 4,000-passenger mega-ship is its best own lifeboat, the saying now goes.

And so the "safe return to port" regulations for new ships 120 meters or longer entered force in 2010.

The new mandate applies to all the major players: Carnival, Princess, Royal Caribbean, Norwegian Cruise Line and HAL. Most of the smaller and luxury lines are in the same boat, too.

There are two components to the regulations. The "casualty threshold" provisions specify the design criteria for how much damage passenger ships must be able to withstand and still safely return to port under their own power. If this threshold is exceeded (i.e., the damage renders a ship unable to limp back on its own), then the ship should remain viable -- i.e. retain the means of internal and external communication; still have evac lighting -- for a minimum of three hours to allow for abandonment.

Among the design criteria outlined by the IMO is a completely separate, redundant electrical system able to maintain the propulsion system, steering and steering control systems, and other systems vital to safety and survivability. In practice, this often means designing a ship with two independently operating engine rooms (rather than linked engine rooms). If one is compromised, crossing cables won't spark the same fate for the other. The ship will still have juice.

The "safe areas" provisions focus on basic services -- sanitation, water, food, alternate spaces for medical care, light -- that are to be available to passengers as the ship returns to port.

But the regulation focuses on new ships -- for which construction began after July 1, 2010. And because the rules look to the future, mandatory compliance is only required of a handful of existing cruise ships, like Carnival Breeze and the soon-to-debut Norwegian Breakaway. There are existing ships that comply to some extent, though they're not required to. For example, the 5,400-passenger Oasis and Allure of the Seas, the world's largest cruise ships, each has two independently operating engine rooms. MSC Divina also features redundant means for propulsion. So what of Carnival Triumph, launched in 1999, Carnival Splendor (2008), Azamara Quest (2000) and Costa Allegra (1969, since scrapped). How do you stop engine room fires from frying the wires and debilitating the ship?

Most modern cruise ships, including Carnival Triumph (1999), have two engine rooms, but the level of redundancy mandated by "safe return to port" is almost always absent from the design. There is some redundancy built in, said a naval architecture expert who wished to remain anonymous because he works in the industry. "For instance, many ships already have double electrical motor systems. So if some electrical components fail, they can continue to operate. But if they are not so lucky -- and an entire engine room is knocked out -- they end up like Carnival Triumph." Or Splendor. Engine rooms on pre-2010 ships are interconnected to the point that a fire in one can take out the shipwide electrical network that both facilitate.

Retrofitting ships to have independent engine rooms or duplicated propulsion systems is not typically a realistic option, experts say.

With older ships, naval architects probably would have to redesign all essential systems onboard. It's not economically feasible, say experts. So the emphasis is on new ships. That's where you can have the most impact without suddenly forcing a multitude of vessels to retire, as happened to the iconic QE2 and others when new international fire-safety requirements went into effect in 2010. There is no requirement for older hardware akin to "safe return to port," explained Natasha Brown, external relations officer for the IMO.

Focusing on new-builds leaves out most of the industry's current stable.

Steps are being taken. For instance, MSC spokesperson Gail Nicholas told us that two of its newest ships, MSC Fantasia and MSC Splendida, will be retrofitted to feature the redundant system setup. (We haven't confirmed if doing so was made easier because of the specific design of those ships.) At the moment, it's been hard to get a beat on what other lines are doing on a granular level. You'd think that modern vessels, even those built before 2010, would feature sophisticated back-up systems that would kick in in the case of emergency.

We reached out to six operators, including Carnival, Royal Caribbean, NCL, Princess, Holland America and MSC, for more information on which ships in their respective fleet comply to the safe return to port regulations (even if not required), if there are plans for updating older vessels, and current automatic fire suppression systems. Holland America referred us to the Cruise Lines International Association, an industry lobby that represents every major player. (CLIA in turn said it couldn't go into detail on any specific line.) Only the aforementioned MSC offered a response.

MSC Divina (debuted May 2012) and MSC Preziosa (launching in March) "are fitted with a duplicated propulsion system enabling them to maintain operating conditions with some limitations in power (but 50 percent of the main power necessary for nominal speed), speed, range and comfort, in the case of any single failure of items relative to the propulsion or power generating system," Nicholas explained. If one fails, the "other does not lose any functionality, providing sufficient conditions for a safe return to port."

According to folks at CLIA, the broader focus has been here: The damage can be mitigated to some extent by the speed at which a fire is snuffed. This can be achieved by training rapid-response crews and integrating automatic extinguishing components like "water mist" systems, which can be quickly deployed to fill a space with a dense fog that sucks the heat from a fire. "Over a relatively short period of time, you've seen water mist systems go from radical methodology to being very much mainstream system" said Capt. Ted Thompson, senior technical adviser for CLIA. Thompson called the water mist system, which has become a staple on new cruise ships over the last decade, the most important advancement in fire protection industry in a long time.

Conventional fire-suppression uses CO2, which is effective -- but it also would kill anyone exposed to it. Crewmembers have to be evacuated and the space sealed before the gas can be deployed.

Rapid suppression is key, said one expert who wished to remain anonymous because he works in the industry.

In a Tuesday night news conference, Chairman and CEO Gerry Cahill told reporters "if you look in this particular situation, the automatic fire extinguishment (sic) worked very well." We've asked Carnival several times by e-mail for information on Triumph's fire suppression system and to clarify the statement the systems "worked very well."

During 2010's Carnival Splendor fire, the CO2 suppression system inexcusably malfunctioned. The vessel's quick-response team was able to manually quell the fire, but not until some five hours after the initial spark. Precious seconds were lost. The intense heat caused damage to two engine control switchboard rooms directly above and melted much of the electrical cabling in the area. The ship was rendered almost useless and had to be tugged to San Diego during a saga the world watched unfold. Months later, the Coast Guard issued a scathing report outlining the failure along with numerous other shocking infractions, including incorrect labeling of components and incorrect instructions for using fire safety equipment.

There were clearly compliance issues. In the aftermath, Carnival set up a Fire Safety Task Force, made up of shoreside and onboard employees (such as captains and chief engineers) to improve the prevention, detection and inspection of fires onboard ships. One of the chief goals of the task force, the line said, was to figure out how to reinforce the redundancies onboard ships so if one engine goes out, the ship doesn't also lose use of the second.

We've reached out for details on what changes were made, but the line has yet to respond.

Regardless, it's happened again. This time, as Carnival points out, the automatic fire suppression system worked -- but how was the outcome any different?

Because Triumph is a Bahamian-flagged ship, the Bahamas Maritime Authority will be the primary investigative agency looking into the causal and contributing factors that led to the incident. Crew response and effectiveness of fire-fighting systems will also be evaluated. The National Transportation Safety Board and the U.S. Coast Guard will be involved in the effort; but regardless of whether the ship is homeported in the United States and carrying predominantly U.S. citizens, the jurisdiction falls to the flag state, said NTSB spokesman Keith Holloway. Results of the investigation will be released to the public once the investigation is complete, Chris Dowty, technical and compliance officer for the BMA, said. We've asked Dowty for additional information on what investigators will be looking for, what they'll tell us -- and what will be done with the findings.

We'll keep you posted.
--by Dan Askin, Senior Editor