Few people would disagree that Navy SEALs are a pretty tough group. Their training alone is more than most of us will experience in our entire lifetime, and that’s only what they do BEFORE they become SEALs. As tough as they are, even a SEAL is vulnerable to the cold, especially when he’s wet. Hypothermia can affect a SEAL just as much as you or me.
So what happens when a SEAL gets wet when it’s frigid out? Well, the same thing happens to them as would happen to us: They get in trouble. How much trouble are we talking about? More than you probably can guess. If you look at the crash of flight 1549 into the Hudson River a few years ago, the 20-degree air temperature and 40-degree water temperature was more than enough to give passengers hypothermia for the few minutes they were exposed. The average person can survive in 41-degree water for only 10–20 minutes before reaching hypothermia.
While the passengers were dressed far less appropriately for the emergency situation than the SEALs were, the fact remains that the combination of water and cold made an already dangerous situation far deadlier.
So how does this relate to you? Well, you’re probably not planning on taking any outdoor baths in the winter, but it’s all too easy to fall through ice on a lake, slip into a stream while hunting, or be forced to enter water to save someone or something during an emergency. As soon as you get wet and cold, the hypothermia clock starts ticking. What do you do?
If you listen to TV survival shows, then you probably guessed that you should build a fire as quickly as possible, strip down to your skivvies, and hang your wet clothes to dry. While this seems like a great idea, it can be one of the worst things you can do.
The Rewarming Drill
John Barkow of Sitka Gear worked with Navy SEALs on how they can survive and recover from becoming drenched in a frigid environment without any external help. He did this by convincing SEALs to drop their packs and walk into a half-frozen lake in the middle of winter during a sleeting winter storm. Any one of those would be too much for most of us, but they (somewhat) gladly did all three.
Barkow said this “was meant to mimic the scenarios you hope to never encounter.” The dunk took place after a three-hour patrol hike, far away from any quick assistance. The SEALs would stay in the icy water for 12 minutes before being allowed to get out.
Instead of stripping off their layers and building a fire like you would think, they instead followed John’s tenant of survival by “getting immediately out of the elements and gaining control of the situation.” So, how do you get control of a situation this dangerous and likely deadly?
Instead of the strip and dry method we assume is correct, Barkow had the SEALS pull their backup synthetic outer layer from their packs and put them on OVER their drenched layers. They split into pairs with one SEAL putting up a small tent and the other preparing the stove to boil water. No fires yet — just a camp stove and boiled snow.
From here, both men got into their tents and into their sleeping bags. Once the water was boiling, they made a hot drink and rehydrated some chili. Once consumed, they continued to lie in their bags and tents and wait. What they were waiting for is for their metabolism to kick into action and start to warm them from the inside out.
After a few hours, the SEALs gradually stopped shivering and were warm enough to function again. During this time, their bodies had nearly dried their base layers, partially dried their mid-layers, and their outer layers were nice and frosted. At this point, they could build a fire if necessary and dry out anything else that needed it while being completely safe without any more risk of hypothermia.
How Does It Work?
So how does this seemingly magical recovery after a 12-minute dunk work? Well, there are a few key items at work here. They are:
- Proper supplies carried in their packs
- Proper layering of clothes
- Warm-when-wet outer layer and sleeping bags
Synthetic layers are the key to being safe in winter weather. While down might keep you toasty when its dry, it can quickly absorb water and lose its primary form of insulation when wet. Cotton is another example of this idea. Cotton holds liquids for an extended period of time, which in this situation, would mean a much slower drying time.
Therefore, cotton and down in both layers and sleeping bags are a big no-no in winter survival situations. Here’s a great instructional piece by REI on proper winter layering. Just ignore the parts about down insulation.
By having a moisture-wicking base layer, the water/sweat is wicked away from your skin to the mid-layer. The mid-layer should be breathable as to allow for moisture to continue its path away from you to the outer layer. Here, it should collect, and if done correctly, the proof should be seen as frost on the outer dry layer.
The only additional layer you need to carry along with you is the emergency synthetic outer layer. The rest should dry with your body’s heat.
There are more “rewarming drills” including one without a tent or sleeping bag. While we strongly recommend you don’t ever try your own rewarming drill, knowing what to wear in case you’re forced into this situation is critical to surviving in cold weather, especially when you have to carry everything on your back and weight/space is at a premium. Check out the full article here and gain a little more respect for Navy SEALs.