There is a fire in one of two engine rooms on a cruise ship. The fire is extinguished but the damage has been done. The cruise ship blacks out – losing power and most electricity. The ship is adrift in the ocean. There is so hot food, hot water, or air conditioning for the several thousand passengers and crew aboard the ship. Conditions aboard become extremely uncomfortable as sewage systems back up, food in refrigerators rot, and the temperatures below decks become sweltering. Finally, tugs are hired to tow the ship into the nearest port.
This could be a description of what is currently happening on the Carnival Triumph, which is now being towed to Mobile, Alabama. It could also equally be an account of what happened on the Carnival Spendor in the Pacific in late 2010, or the Ocean Star Pacific off Mexico in April 2011, or the MSC Opera in the Baltic in June of 2011 or the Costa Allure off the Seychelles in February of 2012. The same thing almost happened on the Azamara Quest off the Philipines in March of 2012. After drifting for 24 hours, the crew was able to restore partial power and electricity and the Azamara Quest was able to make it to port on its own.
The design of each of these cruise ships should make the complete loss of propulsion and main generators due to a single engine fire impossible, yet with six ships disabled in just over two years, the failures are not only possible but apparently chronic.
All these ships have similar machinery layouts. They are, as are most modern cruise ships, all diesel electric powered. Instead of having one or more large engines connected to propellers, these ships use several smaller engines connected to generators which supply electricity to motors which turn the propellers. The generators also keep the air conditioning running, the food hot and the drinks cold. Typically, these ships have two independent engine rooms with three diesel engines in each.
Having two separate engine rooms and six diesel engines driving generators should provide complete redundancy. Even if one engine room is completely out of service, the diesel engines in the other engine room should be able to provide enough power to bring the ship home as well as generating enough electricity to keep the passengers comfortable. That is obviously not what is happening.
What is starting these fires in the first place? The most likely culprit is a crankcase explosion. That is what started the fire on the Carnival Splendor. Crankcase explosions have always been a problem on large diesel engines. If a crankcase bearing overheats it can cause an explosion in the oil rich air in the crankcase. In the Carnival Splendor there was a crankcase explosion in engine #5 in the after engine room, which caused the fire.
How could a fire in one engine crippled the entire ship? For months there was no clear answer. The Carnival Spendor flies the Panamanian flag and does not generally publish accident reports, unlike the US Coast Guard or the NTSB. The first explanation for what went wrong came in a statement made by Carnival president, Gary Cahill in February 2011, as reported in Travel Weekly. Apparently, the heat from the fire damaged local electrical distribution cables but also crippled the ship’s switchboards. While the three engines in the forward engine were completely undamaged, they could not send electricity to the rest of the ship because the switchboards had been taken out by the fire in the other engine room.
As reported by Travel Weekly:
“Having two engine rooms like we do is pretty much the norm in the cruise industry,” explained Cahill. “What we have decided to do, and this will go across the Carnival group I’m sure, is we’ve determined there are certain things that we can do to increase the effectiveness of that redundancy.”
Cahill said these measures include additional suppression systems to put out fires more quickly and additional insulation over the cabling and under the switchboard areas.
Two years later, as the Carnival Triumph is being towed slowly to Mobile, it is clear that there is more to be done. We cannot know for sure that all six instances of ships crippled by an engine room fire were similar to that encountered on the Carnival Spendor. Nevertheless, it seems likely that heat damage to switchboards and cabling is the culprit in most cases. Given the number and frequency of these disabling fires, it is also likely that most modern cruise ships share the same design vulnerability.