Why cruise ships are safe from tsunamis.
One could be forgiven for thinking that the
doomsday prophets are going to have their day
with the recent roll of disasters sweeping our
planet.
Japan, a country used to and quite probably
the best prepared in the world for such an event,
was brought to its knees.
And the story is far from over.
But what for cruising? What if you are caught
at sea during a tsunami warning? Will you become
an unwilling extra in the next Poseidon Adventure?
For film and cruise buffs, the Poseidon
Adventure (1972) was developed from a 1969
novel and spawned three sequels; 1979, 2005
and 2006.
But the basic premise of the ship (any ship) being capsized by a mid-ocean tsunami is
seriously flawed.
In the original movie, it was indeed an earthquake that supposedly sent a 50 metre
wave rolling across the ocean casually overturning ocean liners in its way.
Tsunamis don’t do that.
Tsunamis travel at high speed, up to 800km/h with a very low wave height, from the
undersea quake’s epicentre.
Like the ripples created from a stone tossed into a pond, the nasty breaking waves
only occur when the energy meets a solid object, like a coastline or shallow water.
Because the ‘wavelength’ is long, the energy just keeps on coming and drives water
way inland as we saw on Japanese TV.
So, as evidenced by the complete lack of damage to cruise ships at sea during the
massive 8.9 magnitude earthquake, you can safely ride out a tsunami at sea and
probably not even notice it.
A ‘rogue wave’, however, is a different kettle of fish altogether and still has scientists
discussing the origin and cause.
Yes, ships need to worry about rogue waves.
Several cruise ships have encountered them.
In 2001, Bremen and Caledonian Star were both surprised by a so-called freak wave of
30m in the Drake Passage, perhaps similar to the one that damaged Clelia II last December.
QE2 hit one mid-Atlantic in 1995 during a hurricane and the original Queen Mary
was whacked broadside by one while carrying thousands of troops in 1942.
She listed to 52 degrees, damn near capsized and gave novelist, Paul Gallico, a highly
profitable idea.
Some waves can be predicted by currents, sea floor and weather, such as near South
Africa’s Agulhas Current, but the so-called ‘perfect storm’ conditions can produce what
wave mathematician, Al Osborne, calls ‘unstable non-linear monsters’.
These are the real whoppers that feed off adjacent waves and rise up to absurd
proportions.
The only passenger ship thought lost
due to a rogue wave was the 1909
disappearance of SS Waratah off South
Africa.
Her wreck was never found.
So unless, you are sailing headfirst into
a cyclone, there is little worry you will
encounter one of these waves and as for
tsunamis, you have more to fear from
lightning strike or crossing the road.
Cruising remains one of the safest
forms of transport, true.
