Seasickness is the 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, but people who are particularly vulnerable to the condition can feel seasick simply by stepping foot on a boat, even if the vessel, such as the Royal Yacht Britannia, is in dry dock.

Seasickness can be a debilitating condition and it is extremely dangerous if a sufferer has an important role to carry out, such as steering a yacht through stormy seas while avoiding rocks and other hazards. It is particularly hazardous for scuba divers who, through dehydration following vomiting, are at increased risk of decompression illness.

Contents

1 Cause 2 Seasickness while not at sea 3 Prevention 4 Remedy 5 See also

Cause

Human beings instinctively seek to remain perpendicular, that is, to keep the centre of gravity over the body. This is acheived in various ways, but chiefly by reference to the known position of visible objects. Seasickness often results from the inability to view a reference point, such as the horizon, when on a moving craft while nearby objects are moving with the motion of the craft.

Hence on a ship where the lines of the masts, windows, and furniture are constantly changing, sickness, vertigo, and other afflictions are commonly suffered, especially by 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 influenced by the irregular pressure of the bowels against the diaphragm as their inertia or weight varies with the rising and falling of the ship.

Seasickness while not at sea

Many experience similar effects

• in railway carriages
• on swings
• while looking from a lofty precipice where known objects, being distant, are viewed under a new aspect and not so readily recognised
• while walking on a wall or roof
• while looking directly up to a roof
• while observing the stars in the zenith
• on walking into a round room, where there are no perpendicular lines of light and shade and the walls and roof are covered with an irregularly-spotted design
• on twirling round, as in waltzing

Prevention

Over-the-counter and prescription medications are readily available. Some sufferers find that wearing special wristbands also helps stave off the condition.

Remedy

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 temporarily to diminish their senses of sight and touch
• move into a position where fresh air is blowing on their face
• sucking on crystalised ginger or sipping ginger tea
• keeping near the centre of the boat where any rocking motion is least pronounced

Unlike with a hangover, succumbing to nausea normally does not relieve the symptoms of seasickness, and, once started, is often difficult to stop.

See also

• Motion sickness