Dealing with Seasickness
by Michael Jacobs, M.D.

Seasickness presents a major hazard to crew safety, health, and morale. At the very least it may be moderately disabling; other times, it can lead to rapid deterioration with progressive dehydration, loss of manual dexterity, ataxia, loss of judgment, and, finally, loss of the will to survive. Seasickness, along with fatigue, fear, and loss of morale, is a serious problem, and, all to often, can become the principal reason for a rescue at sea.

It is often preventable and, once in progress, is certainly treatable. The underlying mechanism involves a conflict of signals from various sensors in our body that are processed in the brain’s balance center orienting the body’s position in space.

Place someone in the cabin of a heeling or rolling boat, and you immediately invite sensory conflict. The eyes, oriented to the cabin floor and ceiling, detect no tilt from vertical. Fluid in the inner ear vestibular apparatus constantly shifts with gravity like the fluid and bubble in a carpenter’s level. The position sensors in our neck, muscles, and joints send different signals depending on how we shift and then secure ourselves to prevent falling.

This mix of sensory data from the eyes, inner ear, and position sensors arrives in the brain in complex and conflicting combinations. This neural mismatch is what has been referred to as sensory conflict. It activates a host of other responses and stimulates the vomiting center in the brain.

The balance center has the ability to adapt to the new environment. It is called "getting your sea legs". Medications and a variety of tactics discussed below are useful during the period of adaptation. As one learns to anticipate, compensate and stay in tune with the boat’s motion, the sensory conflict signals disappear. The medication is more effective in preventing symptoms than in reversing them after seasickness has become fully symptomatic. Take anti- motion sickness medication early before leaving port.

Start the trip well-hydrated and avoid any large quantity of alcohol. Eat a light meal. Anecdotal reports favor eating carbohydrates rather than protein, however, there is no conclusive study to favor any particular food or diet. Ginger is often recommended as an anti- emetic, and it is safely and effectively used by pregnant women to curb nausea and vomiting in the first trimester of pregnancy. Ginger is available in 500 mg. capsules. The suggested dose is 1,000 mg. every six hours. The capsules can be supplemented with gingersnap cookies, ginger ale, and candied ginger.

Another modality that might help to prevent seasickness is acupressure. The area to apply pressure is three finger breadths above the wrist joint between the two prominent finger flexor tendons. Elastic wrist straps with buttons known as seasickness bands are available for sailors to use. Some studies on their effectiveness are inconclusive while others show no benefit.

All details of the ship’s preparation and safety check should be done well in advance of departure. This will limit the amount of time spent below deck so as to avoid the sensory conflict until one acclimates to the motion.

After departure it is important to stay on deck and amidships or aft where the pitching and rolling is less severe. Look outwards and obtain a broad view of the horizon using your peripheral vision. This will decrease the sensory conflict by providing a stable and level point of reference. For the same reason, avoid close focused visual tasks like prolonged reading, writing, and navigation that contribute to spatial disorientation and sensory conflict. Stay away from fumes and odors that can stimulate a feeling of nausea. Continue any medication for seasickness at regular intervals and begin to taper the dose after the first day.

The early signs and symptoms of seasickness are yawning, sighing, dry mouth or salivating, drowsiness, headache, dizziness, and lethargy. Pallor, cold sweats, belching, flatulence, nausea, dry heaves, and vomiting are much later signs after the illness is well developed. One of the best tactics when experiencing early symptoms is to take the helm and steer using the waves, clouds, horizon and distant marks as reference points. When sitting in the cockpit, be aggressive and fight back. Postural anticipation of the boat’s motion is the natural cure for seasickness.

Seasick crew members can easily fall or be washed overboard. When on deck they should wear a safety harness or someone on watch should be attentive to them. In storm conditions, the safest place for them is in a bunk.

If symptoms progress despite these measures, it is time to go below deck. Lie down in a secure well-ventilated bunk, face up, head still, then close your eyes and try to sleep. Small amounts of water, crackers, or hard candy may also help. It may be the time to take medication by other routes than solely oral. Twenty-five mg. phenegran may be used as a rectal suppository

There are a variety of medications available for motion sickness. Many are over-the-counter (OTC) requiring no prescription. Find a drug for you which has minimal side effects. Experiment by taking these medications on the suggested schedule while on land. If one is not suitable, try another. The time-release forms and longer-acting drugs may be preferable when storms at sea are expected to last a few days. The OTC antihistamines all have potential side effects which include drowsiness, dry mouth, blurred vision, irritability, urinary retention, dizziness and headache.

Transderm scopolamine has been redesigned and is again available by prescription. By placing a dime-size adhesive patch behind the ear several hours prior to departure, scopolamine is delivered into the bloodstream at a constant rate to provide a therapeutic blood concentration for up to three days with minimum or no side effects. The most common adverse effects are dry mouth and drowsiness. The patch is contraindicated for children, people with glaucoma, and men with prostatic hypertrophy.

Taking preventive measures can help prevent seasickness, and an awareness of symptoms can help one deal effectively with the condition while at sea thereby avoiding major problems.

Michael Jacobs, M.D., lectures and writes on marine medicine topics. He is a practicing physician in Massachusetts and is an instructor for Wilderness Medical Associates