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.
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.