Such an occurrence, Radisson Seven Seas Cruises' Andrew Poulton told Cruise Critic today, would be highly unlikely.
Indeed, when the tsunami began to strike the coastlines of 12 different countries in South Asia, a handful of cruise ships, such as Star Clippers' Star Flyer, Seabourn's Spirit and Swan Hellenic's Minerva, were sailing, if not right in affected areas then in the general oceanic vicinity. None reported any damage to the vessel -- or injury to passengers and crew. In fact, Poulton says, "If you are on a cruise ship and in the ocean you might not even notice it."
Tsunamis travel at speeds of 500 miles per hour across the open sea, Poulton adds. "People may think of it as a wall of water coming across the ocean, but it's not. It's a shock wave sent across the sea. When it gets to shallow water it compresses and is forced into a huge wave -- because it's got nowhere to go. It only becomes an issue when the water hits land."
Even ships docked, pierside, likely won't be horribly affected should a tsunami approach. That's because most cruise ships need at least 30 feet or so to dock, which is actually fairly deep (15 ft. deep, on the other hand, would be considered shallow). However, the caveat is: ships must be tied with super extra care.
A story on today's wire services backs that up. In a report issued by Bloomberg, the government of India is warning that, as a result of aftershocks, another tsunami could occur. At Madras' Chennai Port, which is primarily a cargo port, loading was halted -- and 15 ships were anchored in the harbor rather than sent out to the open sea (cruise lines have already altered itineraries away from the impacted areas).
The worst-case scenario is that the wave, approaching the docked ship, could be fairly "large at that point and may knock the ship against the pier -- but it wouldn't capsize," Poulton explains. Far scarier for cruise passengers than a tsunami, he adds, is a rogue wave. He noted that some years ago when he worked for Cunard, Queen Elizabeth 2, sailing in the Atlantic, was almost suddenly slammed by a 90-foot wave -- a freak condition, Poulton says. "Thank god the captain actually saw it coming on radar," he says. "It was like a wall and he faced the ship right into the wave. There was some structural damage, but nothing else."