Seasickness
Seasickness is a form of motion sickness characterized by a
feeling of nausea and, in extreme cases, vertigo experienced
after spending time on a craft on water. It is typically brought
on by the rocking motion of the craft. Some people who are
particularly vulnerable to the condition can feel seasick simply
by setting foot on a boat, even if the vessel is in dry
dock.Others are relatively immune, or become immune through
exposure.
Seasickness can be a debilitating condition and can be dangerous
if the sufferer has an important role to carry out, such as
steering a yacht through stormy seas while avoiding rocks and
other hazards. It is also particularly hazardous for scuba
divers who, through dehydration following vomiting, are at
increased risk of decompression illness.
Cause
Seasickness is not a virus and there for you cannot “catch it”.
Most people are affected by motion sickness to varying degrees.
There are certain treatments that may help to prevent the onset
or at least shield you from the very worst effects of seasickess.
There are three seasickness triggers guaranteed to cause suffers
uncomfortable symptoms. These triggers should be avoided
whenever possible during the initial boarding and first few
hours at sea:-
* Going below deck for extended time periods. Not easy if the
weather is poor and impossible on some boats such as hovercraft.
At least try to find a window or porthole and keep your eyes
gazing at but not fixed on the horizon.
* Looking through binoculars for anything longer than a glance
* Reading a book, looking at a compass, doing detailed work or
staring at one point. Try to keep your peripheral vision out on
the horizon and not staring at objects your brain will interpret
as stable.
Human beings instinctively seek to remain upright by keeping
their centre of gravity over their feet. The most important way
this is achieved is by visual reference to surrounding objects,
such as the horizon. Seasickness often results from the visual
confusion on a moving craft, when nearby objects move with the
motion of the craft. Because the lines of the masts, windows,
and furniture on a ship are constantly shifting with respect to
fixed references, humans can suffer a number of afflictions,
especially those unaccustomed to being at sea.
Sea-sickness has such a remarkable effect because both the sense
of sight and touch are disturbed by the motion of a craft on
water. The severity of seasickness is also influenced by the
irregular pressure of the bowels against the diaphragm as they
shift with the rising and falling of the ship.
In his book The Human Body, Isaac Asimov related the anecdote
about a seasick passenger whom a steward cheerfully assured that
nobody ever died from seasickness. The passenger muttered,
"Please--it's only the hope of dying that's keeping me alive."
Prevention and remedy
Over-the-counter and prescription medications such as dramamine
and scopolamine (as transdermal patches and tablets) are readily
available. Ginger capsules are also considered effective in
preventing motion sickness. Some sufferers find that wearing
special wristbands helps stave off the condition.
Those suffering from seasickness who are unaccustomed to the
motion of a ship often find relief by:
* keeping their eyes directed to the fixed shore or horizon,
where possible
* lying down on their backs and closing their eyes
* drinking any substance that is likely to temporarily diminish
their senses of sight and touch
* move into a position where fresh air is blowing on their face
* sucking on crystallised ginger, sipping ginger tea or taking a
capsule of ginger.
* moving to the boat's center of gravity to eliminate motion due
to pitch, roll and yaw (but not translation)
* taking the helm of a yacht can reduce sickness as the sufferer
has something to concentrate on, and can also anticipate the
movement of the vessel
Unlike with a hangover, succumbing to nausea normally does not
relieve the symptoms of seasickness, and, once started, is often
difficult to stop.
