What If I'm Wearing a Wetsuit or Drysuit?

A lot of people are under the misconception that you have to choose between dressing for the water temperature and overheating. They cite a concern about "hyperthermia" as a reason to skip thermal protection when the air temperature is high. They simply don't understand how to use evaporation and conduction to keep cool.

 

Your Key To Comfort:

Get the surface of your wetsuit or drysuit wet.

Wet your hair and wear a wet hat, wet bandana, or anything that will allow you to offload heat via evaporation.

 

Fabrics differ in how efficiently they absorb water. My old wetsuit absorbs enough water to provide evaporative cooling for 20 – 30 minutes. However, a lot of the newer neo sheds water and won't work for evaporative cooling unless you wear a wet shirt over the top of it. Same holds true for some drysuit fabrics. BTW: Moving air increases the efficiency of evaporation and high humidity retards it.  Note: You can still use evaporation to keep cool when the humidity is high.

​

 

A Dynamic Process

I want to emphasize that this is a dynamic process. You have to work with it to maximize both conduction and evaporation and that takes some practice. Because I take advantage of these techniques, I don't have a problem with overheating when wearing thermal protection in warm or hot weather.

 

 

14mm of Neo

For example, before I moved to Vancouver, WA, I paddled in the Chesapeake Bay area of Virginia, Maryland, and Delaware, where it wasn't unusual to have 95F days with high humidity in summer. I occasionally demonstrated the power of evaporative cooling to my students by wearing my two-piece wetsuit in August – a 7mm farmer john under a 7mm long-sleeved shorty. That's 14mm of neo over my core, and I topped it off with a full-thickness neo balaclava hood. As long as I kept the neo wet, I was fine. If the neo was dry, I would have had a fatal heat stroke in under 20 minutes. That's the power of evaporation!

​

 

What About Cotton?

When I posted this article on several Facebook paddling groups, I received some pushback from people who questioned why I recommended cotton clothing for paddling. They felt it was dangerous to wear cotton and they repeated the “cotton is rotten” mantra as if it applied to hot weather. It doesn't.

​

Bottom line: In wilderness travel, all the caveats about cotton apply to those cold weather occasions when the issue is keeping warm.  That includes situations where you might encounter a 50F rainstorm on an otherwise warm day.

​

• However, this article is about keeping cool, not about keeping warm. It's about avoiding overheating by using evaporative cooling. It applies to hot days when you're paddling on warm water and also to hot days when you're paddling on cold water wearing thermal protection like a wetsuit or drysuit.

​

• When you wet your clothes on a hot day, they will generally dry out in under 20 minutes. You are in complete control of the re-wetting process. When you have plenty of access to water, this is the most effective way to use clothing to regulate your personal comfort. This technique allows you to use your clothes as your thermostat, and you control the set-point by deciding when to add water and how much water to add. With a little practice, you can dial in comfort and paddle on an hot day in full sunlight – while feeling like it's 75F outside. As an additional bonus, you'll avoid the need to guzzle fluids to replace those that you lose by sweating.

​

• The ability to stay comfortable in the outdoors regardless of the weather takes knowledge, skill, and practice, but the techniques involved in keeping warm and keeping cool are fundamental to both safety and comfort.

​

• I've personally used these techniques for over 50 years - as have countless other experienced wilderness travelers. If you're new to the game or simply missed that memo, please make sure you understand this article and have tried out the techniques before you jump in and start criticizing anything about it.

​

• If your goal is keeping warm and avoid cold stress, then cotton should be avoided. Cotton fibers soak up water like a sponge, offer zero insulation when wet, and take much longer to dry than synthetics. For example, getting caught without raingear in a 50F rainstorm on a mountain trail, while wearing cotton, is an invitation to hypothermia.

​

• However, if your goal is to avoid heat stress, then cotton is a superior fabric because it holds more water and doesn't have to be re-wetted as often as synthetics.

​

• There are no exceptions to the rule “Always Dress For The Water Temperature”. Just because the weather is hot, you don't skip wearing a wetsuit or drysuit when you paddle on cold water. Dressing in layers is not going to protect you if you wind up in cold water – whether those layers are cotton or synthetics.

​

• You don't wear cotton under your drysuit, but you can wear cotton over your wetsuit or drysuit if you need additional evaporative cooling.