How To Stay Hydrated When Sailing

What is dehydration?

Just as a car needs fuel and oil to run smoothly, so the body needs water and electrolytes to perform all the cellular processes necessary to function and communicate. If their level is too low, the body will not function properly, either physically or mentally. If you are sailing you may find the physical effort of boat handling suffers and you may not be able to make clear, considered decisions.


It is all too easy to become dehydrated on a boat:-

  • If you are busy sailing, racing or short handed you may not feel that you have the time to go below and get a drink.
  • You may find that drinking water from your tanks doesn’t taste particularly palatable, so you put off topping up.
  • If you are feeling a little queasy you may not want to risk drinking too much and then having to go below to the heads. Similarly if you are wearing full foulies in bad weather, it is a real pain to have to go below and strip off, especially for females and the “bucket and chuck-it” regime can be rather embarrassing.
  • You may be drinking what you think is an adequate amount, but is it the right stuff. Fizzy drinks and alcohol will not help you.

What are the symptoms?

Two early symptoms of dehydration are thirst and dark-coloured urine. Others may include dizziness or light-headedness, headache, tiredness, dry mouth, lips and eyes and passing small amounts of urine infrequently (less than 3 or 4 times a day). At this level it can cause loss of strength and stamina, but you should be able to reverse the effects by drinking more fluids.

If dehydration is allowed to become ongoing or chronic, it can affect kidney function and increase the risk of kidney stones. It may also lead to muscle damage and constipation. In this case you should seek medical advice. If left untreated it can become severe and would be a medical emergency requiring immediate attention.

Most cases of dehydration whilst sailing are of the non-emergency type which, with a bit of common sense and change of routine, can be easily managed and dealt with as long as they are recognised. Interestingly dehydration is thought to be a leading cause of irregular on-the-water performance for many sailors and crews.

What are the causes?

Fairly obviously, dehydration is caused by not drinking enough fluid or by losing more fluid than you take in. Fluid can be lost through urine, tears and (especially relative to sailors) sweating, vomiting and diarrhoea. The severity can depend on such things as climate, level of physical activity and diet.

Sweating: You don’t have to be sailing in the tropics to find yourself sweating a lot. Carrying out the manual work necessary on a boat, such as heavy winching or handling hooked on sails may cause you to sweat profusely. Children and teenagers are particularly at risk because they may not recognise the symptoms.

Alcohol: On a boat the sun always seems to be “over the yard arm” and the temptation to have a few extra beers at lunch time and some gin and tonics when you think you’ve finished for the day is very great. But alcohol is a diuretic and the headache associated with a hangover is simply the indication that your body is dehydrated. So if you are drinking alcohol you should also be drinking plenty of water as well.

Vomiting: Seasickness is an obvious cause of dehydration. Many sailors just get the symptoms without actually vomiting, but if you do, you must make sure that you hydrate yourself well. You probably won’t feel like eating or drinking but small sips of water initially will help, or a piece of dry bread to settle your stomach until you can take something more useful on board.

Diabetes: I have sailed with several diabetics who are potentially at risk of becoming dehydrated because they have high levels of glucose in their bloodstream Their kidneys will try to get rid of the excess by creating more urine, so their bodies will become dehydrated from going to the toilet more frequently. They must take extra care.

Treatment and prevention

• Drink plenty of fluids in the form of water, diluted squash or diluted fruit juice, or semi-skimmed milk.
• A sweet drink and a salty snack can help replace lost sugars and salts.
• Rehydration solutions contain a mixture of potassium and sodium salts as well as glucose and starch which facilitate faster fluid absorption. These can be obtained over the counter or on prescription.
• Prevent dehydration by drinking water regularly. Your aim should be around 3 litres per day for men and 2.2 litres per day for women, but be guided by your thirst, the temperature and your level of exercise.
• Remember that not all the fluids you drink are helpful. Tea, coffee and alcohol are diuretics so although they are a source of fluid, they will increase the kidney output.

A warning – It is possible to over do it with re-hydration. It is a condition called hyponatremia, which has been known to cause death, but its cause is more to do with conditions of the heart, liver or kidneys. It is not easy for a sailor or an average athlete to reach such a state, unless they intend to consume gallons of water at one sitting.


The skipper may not count it as one of his tasks to make sure he keeps an eye on crew hydration, but it would pay dividends to do so. If he wants a healthy, well motivated crew who can concentrate and perform, then he should make sure that he has enough fluid available on board, provide opportunities for his crew to drink and visit the heads often enough and to lead by example.

Don’t get it wrong – I’m a great believer in the gin and tonic when the sun is somewhere near the yardarm. I’m just saying – take a good deal of water with it!

Author - Dee White

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