“Although motion sickness may never actually kill us, there are times when we wish it would!”

Ya Huang

“Although motion sickness may never actually kill us, there are times when we wish it would!” said Sanders and McCormick (experts in human factors for industrial designs). This well-meaning quote reminds us that motion sickness can threaten sea kayakers' survival. 

The thrill of kayaking or paddle boarding through the waves will tempt many people onto the water this summer. But experienced kayakers will be dreading the motion sickness that can cripple even seasoned paddlers. Unfortunately, the stomach-churning reaction to motion sickness will not end until the stimuli, i.e. the oscillating sea motion, stops. There are things you can do to prevent motion sickness ruining an ocean adventure. 

What causes motion sickness 

The human body has three groups of motion sensors: visual (eyes), vestibular (inner ears) and somatic (muscles and joints) systems. The brain's "vomit centre", a dedicated area that processes motion, is triggered when it gets contradictory readings between two or more sensors. This activates the body's response to poison - it makes you retch. It's not known why the body reacts in this way. Other stimuli, such as pain, fear, dehydration, temperature and smells, can increase the vomit centre response. 

There are two types of sensory conflicts. The first is between our vision and the vestibular system in our inner ears. This is what causes most car, flight and sea sickness. For example, the book you read in a moving car remains relatively stationary, but your inner ear can feel the vehicle accelerating, braking and turning. Kayakers and paddleboarders suffer this type of motion sickness too. 

If you read maps on the deck and watch moving waves next to your kayak or paddleboard, your eyes tell you that you are not moving much. This is a contradictory story to what your inner ears tell you as your body moves along with your kayak. Your inner ears measure motion relative to the ground (the sea floor). 

The second type of motion sickness is between two motion sensors within the vestibular system: the cupula (the gates of three perpendicular tiny canals sensing the passing fluid so as to detect rotation and acceleration) and the otolith (carpets of tiny hair detecting the direction of gravity and other accelerations). This type can be triggered when the kayaker is upside down and attempting a roll or trying to climb back into the cockpit using a corkscrew rotation

How to deal with kayak motion sickness

Looking far ahead to the horizon will help match what your vision is telling your body with your inner ear sensors. Focus on controlling your kayak and try to anticipate how your boat will move. We never hear a car driver’s complain of motion sickness. It is not just because the driver has a clear view of the horizon. The driver's input – steering, accelerating and braking – creates a feedback loop always coherent to what they see and what they anticipate. Likewise, an actively engaged paddler with the clear view of the field afar would reduce their risk of sensory conflict. 

There are conditions which restrict your view of the horizon or land. 

In a tide race, surface waves swell high enough to block your view of shorelines. The paddler will struggle to move forward because currents underneath the boat flow against the wave they are trying to surf. Less experienced paddlers tend to focus on the boat deck and waves close by for balance and control. This is a potential recipe for motion sensor conflict. Fortunately, most tide races are close to the shore. Gliding your kayak sideways so that you have a better view of the seashore, or a glance at (stationary) clouds near you every now and then may help. 

Tidal channels, typical in the Solent (a strait between the Isle of Wight and the British south coast), create a similar effect. But when you're crossing the Solent with high enough swells, your only stable visual reference point is likely to be the sky. Under these conditions, it's critical to drive your craft over the swells at a consistent pace. This helps reinforce the coherence between the control input and anticipation. 

Subconsciously experienced paddlers use several techniques to help prevent motion sickness. They peek at the compass and map on the deck as little as possible. But they regularly scan their surroundings to check navigation markers at distance and stay aware of where their fellow paddlers are. They change their pace and position from time to time to check everyone is well. This change reinforces the agreement between their control input (anticipation) and the feedback from their motion sensors. 

The exact same concept called anticipatory motion cueing became an active research area for reducing motion sickness for autonomous cars. Passengers with access to visual, auditory, or cognitive cues of future vehicle motion showed a 25% potential reduction in [onset of motion sickness] (O.X. Kuiper, J.E. Bos, C. Diels, E.A. Schmidt 2020, Knowing what’s coming: Anticipatory audio cues can mitigate motion sickness”, Applied Ergonomics, 85). However, key parameters to understand their relative effectiveness and user experience remain unchartered territories. Multiple parameters, such as visual, auditory, tactile, multi sensory cues, their timing, and the way central peripheral information are presented, all have a role to play. A motion sickness free multitasking experience in an autonomous car is still yet to come. 

The good news is that it is possible to build tolerance. Repeated exposure almost always results in desensitisation, even for the most susceptible. 

To the rescue 

Rescue situations expose both the rescuer and the capsized paddler to sensory conflicts as they will have to concentrate on coordinating their hands, equipment, and fellows at close proximity. This is why rescue practice is essential. The less time you spend thinking about the technique, the less time you'll spend looking down and close. 

The footage shows three experienced sea kayakers rescuing a fellow paddler who has capsized in a moderate tidal race zone in the Solent. The wave peaks every five seconds, which is enough to trigger the visual-vestibular sensory conflict in most people. 

Sea kayaking is an incredible way to experience nature, get fit and introduce a sense of adventure into your life. Taking steps to prevent motion sickness will help keep you and others safe on the water. You want your paddle to be unforgettable - for all the right reasons.