Sea Sickness – You Have Nothing to Lose but your Cookies

They say that, when you’re seasick, you start off worrying that you might die, and then, after a while, you start to worry that you won’t die! I know from personal experience, seasickness is a debilitating affliction that can destroy the otherwise ideal day of diving. Understanding the causes of seasickness enables you to work on preventing the problem.

The Causes of Seasickness

The more we can understand what makes people seasick, the better we can respond to minimize these underlying issues, thereby helping prevent seasickness itself.

Movement

This should be obvious. Being at sea on a boat or ship that is moving about a great (or, for some people, not so great) deal, and slow or fast changes in velocity in general, all can cause sea sickness. If you have ever been on a boat on the Great Lakes, the distance between each wave is much shorter than what is found in the major oceans. This form of “chop” can bring even the manliest of men to their knees.

Visual disorientation

The other cause is not quite so obvious. Visual disorientation is when your body senses you are moving, but when your eyes see no movement.

It can also happen the opposite way – for example, in an IMAX theater, you might receive strong visual information suggesting that you’re moving, but your body feels no sense of motion. This can also make you ill, but fortunately, there’s an easy cure for this – simply close your eyes.

Medical explanation

The symptoms of motion sickness include nausea, vomiting, and dizziness (vertigo). Early signs are paleness, salivating, yawning, sweating and a general feeling of discomfort and not feeling well (malaise).

[tag]Motion sickness[/tag[ relates to our sense of balance and equilibrium. Researchers in space and aeronautical medicine call this sense spatial orientation, because it tells the brain where the body is in space - what direction it is pointing, what direction it is moving, and if it is turning or standing still.

Our sense of balance is regulated by a complex interaction of the following parts of the nervous system :

• The inner ears monitor the directions of motion, such as turning or forward-backward, side-to-side, and up-and- down motions.
• The eyes observe where the body is in space and also the directions of motion.
• Skin pressure receptors such as those located in the feet and seat sense what part of the body is down and touching the ground.
• Muscle and joint sensory receptors report what parts of the body are moving.
• The central nervous system processes all the bits of information from the four other systems to make some coordinated sense out of it all.

The symptoms of motion sickness appear when the central nervous system receives conflicting messages from the other four systems -- the inner ear, eyes, skin pressure receptors, and the muscle and joint sensory receptors.

For example, imagine you are riding in an airplane during a storm, and the plane is being tossed about by air turbulence. But your eyes do not detect all this motion because all you see is the inside of the airplane. Consequently, your brain receives messages that do not coordinate with each other. You might become air sick.

Minimizing the Causes

We need to understand the reasons why we get seasick in order to either prevent or minimize the affliction. Usually the sickness causing situation is of temporary rather than permanent duration, and so if you can minimize the impacts on you, there is a better chance you’ll last out until you’re back in calm conditions once more, with both your dignity and your stomach intact.

Minimizing movement

When you’re on a boat, try and get as close to the boat’s center of motion as possible. This is in the middle of the boat, close to the waterline. If you are at the bow or stern, you’ll experience more motion than at the middle of the ship or boat. If you’re on the port or starboard railing, you’ll again get more motion than if you’re in the center of the boat. And if you’re on the top deck, once again you’ll be feeling more pronounced movements than if you’re lower down, close to sea-level.

In trying to find the optimum place on a boat, it might be necessary to consider some compromise so you are also in a place with fresh cool air and a view outside. Make sure you are away from the exhaust from the boats engines. This may also increase the impact of seasickness on you. So give yourself a steady stream of fresh air.

Minimizing visual disorientation

You should focus your eyes at a distant point, preferably the unmoving horizon.

Don’t face backwards. This aggravates the feeling of visual disorientation.

If you’re unable to look at a far-away and hopefully unmoving point of reference, then closing your eyes might be better than staring at close-by things and adding to the sense of spatial confusion caused by feeling the sensation of movement but with no apparent movement visible.

If nothing else, closing your eyes might help you to relax.

And also

If you are with other people and are embarrassed at feeling unwell, try and find somewhere private where you can suffer stoically and alone. The fear of being sick is a powerful magnifying factor that can make you very much more likely to become sick than if you’re not so worried at the thought of possibly being sick. Almost all divers on the Great Lakes have suffered a bout of seasickness at some point in time. So if you find yourself over the edge of a dive boat, don’t feel too ashamed. We’ve all been there.

Try to avoid other divers who may also be seasick. There’s nothing like the sudden and powerful combination of sight, sound, and smell of another diver vomiting to bring you past the ‘point of no return’ as well.

Try to be healthy and well, so your body has more natural resistance. Don’t be hung over, don’t be drinking alcohol, and avoid any food extremes that might give you an upset stomach, even when on dry land. You definitely don’t want to have a lot of food and liquid sloshing around in your stomach, so eat and drink in moderate balanced portions.

Try and be well rested.

Lastly, be prepared, so if you do need to be sick, you’re able to do so with a minimum of mess. If you do have to vomit, make sure you do it on the leeward side of the boat. That is, you don’t want to puke into the wind. It will just end up back on you or all over somebody’s dive gear.

Don’t be embarrassed. You have nothing to lose but your cookies.

Dive Safe,
Duane Johnson
Precision Diving

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