Why does it take hours to evacuate a sinking ship?

Answers to your questions about the news.
April 9 2007 6:56 PM

Abandon Ship! Very Slowly!

Why does it take hours to evacuate a sinking vessel?

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Listing cruise ship. Click image to expand.
The Sea Diamond, sinking

A cruise ship, the Sea Diamond, ran into a reef off the coast of Santorini, Greece, on April 5, tearing a hole in the hull that sank the vessel 15 hours later. The nearly 1,600 passengers and crew didn't get off the ship for three hours. Why does an emergency evacuation take hours?

Slower evacuations are safer. According to the International Maritime Organization's Safety of Life at Sea guidelines, the crew of a ship must be able to lower all the passengers in lifeboats within half an hour, once everyone onboard has been "mustered," or gathered from throughout the ship. But captains don't always evacuate that quickly, because a hasty exit can be dangerous. Panicky passengers can injure themselves as they run, shove one another, and collide in the chaos of flight. Evacuees aren't their normal selves; one study (click for PDF) found that 70 percent of passengers are bewildered with impaired reasoning after serious maritime incidents, 15 percent exhibit irrational behaviors like uncontrollable weeping, and only 15 percent remain calm and alert.

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These dangers might be acceptable in a critical emergency; for example, if a ship were quickly taking on water and about to sink. But in less dire situations, the ship's master will tend to use all the available time to ensure a safe evacuation. Even with the Sea Diamond's three-hour evacuation, though, some passengers suffered broken arms. The captain might also hold up the evacuation while he or she gathers more information about what's happening. A captain won't abandon a vessel unless it's sure to sink, since even a damaged ship offers more protection than a life raft.

Evacuation from the Sea Diamond might have been slowed because it was listing, or tilting to one side. Safety researchers say the tilt likely slowed the evacuation by 10 percent, by forcing passengers to walk more slowly and hold handrails. (More significant listing can be disastrous.)

When does evacuation begin? When the captain sounds the mustering signal—seven short horn blasts or bell rings followed by a long one. Passengers gather at the mustering stations assigned to them during evacuation drills held at the start of the cruise. Each passenger grabs a life jacket from his or her cabin or at the mustering station. There's supposed to be plenty to go around—usually two for every person—but this wasn't the case on the Sea Diamond, where some passengers fought over life jackets. Teams of crew members sweep cabins one by one for stray passengers, marking each cabin that has been checked. The crew also prepares lifeboats, using cranelike structures called davits to lower the boats to the decks where passengers have assembled.

Everyone waits at the mustering stations until the captain gives the final signal (by radio this time) to abandon ship. From there, it can take as little as five minutes to pack a lifeboat with 50 to 200 passengers and up to a minute to lower the vessel to the water—a descent of five stories or more. (It's unusual for passengers to disembark by slide or rope ladder, as happened on the Sea Diamond.) The crew gets off the ship last; sometimes they must resort to chutes and slides to reach life rafts that are already on the water.

Got a question about today's news? Ask the Explainer.

Explainer thanks Andrew Carran of BMT Fleet Technology and Capt. Ted Thompson of the Cruise Line International Association.

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