Whether you’re planning a day trip, a weekend cruise or an extended coastal voyage, some medical issues commonly occur at sea. Many are preventable, and others can be managed on board long before they require advanced medical care. A basic understanding of likely problems, a well-stocked medical kit and a clear, user-friendly guide to marine medicine will help keep everyone safe, healthy and comfortable while underway.
Seasickness, or mal de mer, is the most frequent and dreaded condition among boaters; most people are susceptible to it. Left untreated, seasickness can quickly impair both physical ability and mental focus, creating a serious hazard to safety and morale. In rough weather it is often regarded as a medical emergency, sometimes triggering unnecessary and risky evacuations. Because of its rapid and dramatic impact, seasickness deserves careful attention and prevention.
Seasickness arises when the brain’s balance center receives conflicting sensory signals about body position. For example, someone below deck on a rolling, heeling boat will have visual cues showing a stable cabin interior while the fluid in the inner ear moves with the boat’s motion. Position sensors in muscles, joints and the neck add additional information based on body movement. When these inputs disagree, the resulting sensory mismatch triggers the cascade of symptoms we call seasickness, most notably intense nausea and vomiting.
The key to prevention is reducing sensory conflict—especially the mismatch between what your eyes see and what your inner ears feel. If visual and vestibular cues match, your brain can orient the body correctly and you are far less likely to feel ill.
Prevention
Prepare before you leave the dock so you minimize time spent below deck while the boat is moving. Avoid close-up tasks such as reading or doing detailed chart work. Spend time in the fresh air, avoid engine fumes, and position yourself near the boat’s center where motion is least pronounced. Light, starchy snacks like saltines and steady sips of water or juice can help. Keep your eyes on the horizon or another distant fixed point to provide a stable visual reference.
Maintain an upright posture with your head and upper body balanced over your hips, and try to anticipate the boat’s motion by “riding” the waves—standing at the helm helps you do this. When steering, use the horizon, clouds, approaching waves and distant landmarks as visual references; steering by those external cues is very effective at reducing sensory mismatch.
It can take up to three days to adapt to a vessel’s motion and get your “sea legs.” Medication and preventive measures tend to work better than trying to reverse symptoms once they have developed, so start prevention early if you expect rough conditions.
Start trips well hydrated and avoid alcohol. Eat a light meal low in fat and higher in carbohydrates. If you anticipate susceptibility, begin antiemetic medication the night before departure. Over-the-counter options such as Bonine and Dramamine and prescription choices like Phenergan can be effective when dosed according to instructions. Some of these drugs cause drowsiness; stimulant medications such as Sudafed or NoDoz may offset that effect for some people. The transdermal scopolamine patch (Transderm-Scop), applied behind the ear about two hours before departure, lasts up to three days and may produce less sedation—discuss side effects with your physician. Scopace tablets allow adjustment of scopolamine dose to help manage side effects.
Alternative and complementary approaches may also help. Ginger in capsule form (often suggested around one gram every six to eight hours) or ginger-containing foods and beverages can reduce nausea for some individuals. Devices such as the ReliefBand deliver small electrical pulses to the P6 acupuncture point at the wrist; when positioned correctly the wearer feels a pulsed tingling across the palm and middle two fingers. A simple elastic band with a pressure stud placed at the same point can be effective for some people as a non-electrical option.
No single remedy works for everyone. Different medications, devices and herbal remedies succeed for different people. If one approach fails, try another while still on land so you can evaluate any side effects safely. Once you find a reliable, safe system that works for you, stick with it and trust your routine.
Symptoms and treatment
Early signs of seasickness often include yawning and drowsiness, followed by dry mouth, headache, dizziness and a general loss of energy. Some people first notice a mild queasiness, slight sweating, flushing and a warm feeling. As symptoms progress the skin may become pale, cool and clammy. Nausea typically comes in waves, often with belching and increased salivation before vomiting begins.
At the first warning signs, start treatment promptly. Prescription anti-nausea medications such as Phenergan, available as pills, suppositories or injections, can prevent vomiting and reduce the risk of dehydration. During an episode, lie down and try to sleep; rest helps the body recover. Sip small amounts of fluid and take occasional crackers or hard candy to maintain energy and reduce stomach upset.
Today there are many options to manage seasickness, and effective prevention and treatment mean you do not need to follow the old advice to “find a good big oak tree and wrap your arms around it.” With preparation, the right supplies and an approach that matches your individual response, most boaters can enjoy time on the water without debilitating illness.
Dr. Michael Jacobs is co-author of “A Comprehensive Guide to Marine Medicine” and has written extensively on medicine for mariners and safety at sea. He founded MedSail, teaches marine medicine nationwide, and practices medicine on Martha’s Vineyard, Massachusetts. He is also a lifelong sailor.
This article originally appeared in the January 2009 issue.