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Keeping Your Critical Gear Dry (Part 1)

by , May 11, 2015

When it comes to hypothermia, prevention is better than cure. Avoiding hypothermia is one of the key things that outdoor enthusiasts should be aware of and prepare for – and adequately protecting your gear plays a major part. Jim Wood, outdoor blogger royalty, has kindly allowed us to republish his classic post Keeping Your Critical Gear Dry which provides excellent insight and considerations for protecting your pack contents from the elements and reducing your risk of hypothermia. Enjoy part 1 below…

Jim Wood

Although reliable statistics are difficult to come by, it’s probably safe to say that hypothermia is one of the most significant risks faced by anyone who ventures into the wilderness. Drownings, cardiac events, heat stroke, lightning strikes, avalanches, falls, illnesses, and even animal attacks cause backcountry deaths every year, but hypothermia is almost universally cited as the leading cause of fatalities. Several factors, including low temperatures, high winds, dehydration, insufficient calorie intake and exhaustion levels can contribute to the development of hypothermia, but perhaps the most dangerous is being wet.

Many years ago, as a novice backpacker, I had my first opportunity to observe hypothermia at work during an autumn trip into the High Sierras. I was traveling with two more experienced hikers, one of whom, as it turned out, was conspicuously unprepared for the conditions we encountered. Temperatures unexpectedly fell into the mid-30’s and the skies opened up with a multi-day barrage of rain, snow, and sleet. During a soggy bushwhack down a manzanita-choked canyon, this man, who was wearing only a light shirt and plastic poncho for upper body protection at the time, began behaving strangely. My other companion and I noticed that he was shivering uncontrollably, that his lips had turned blue, and that his speech had become slurred and nonsensical.

Tent after storm

It was clear he was in serious trouble, so we stopped to make an emergency camp. Unfortunately, the jacket in his pack was soaked, as was the sleeping bag that was carried in a leaky stuff sack. So we pitched our tent and hustled our stricken companion into my sleeping bag (which had been well protected) and built a fire to help dry out some of his saturated gear. It required several hours (which included a period of delirium), along with the gradual administration of warm drinks and a bit of food, to slowly bring him around. The following morning, the sun came out and the three of us went on to complete the remainder of our trip. To this day, however, I have no doubt that if he’d been hiking alone, he would have died that afternoon.

I’ve had my own brushes with hypothermia over the years, all of which have been highly unpleasant. If there’s any lesson I’ve learned, it’s that hypothermia is an insidious adversary. Under the right conditions, it can sneak up on a hiker so easily that it’s probably inevitable that anyone who spends any length of time in the wilderness will eventually experience its effects. And unless a warm, dry refuge is available during the early stages, it can quickly become deadly. That’s why protecting critical insulation items like sleeping bags and filled jackets from water absorption can be vital to survival. I’m particularly sensitive to this issue since I backpack mostly alone, which means that there won’t be anyone around to take charge if I begin to “weird-out” from hypothermia.

Image source: http://www.outdoorresearch.com/blog/stories/10-tips-for-making-rainy-backpacking-way-better

Image source: http://www.outdoorresearch.com/blog/stories/10-tips-for-making-rainy-backpacking-way-better

Strategies for Keeping Gear Dry

Because of my experiences, I have a fairly conservative notion of what it means to “protect critical gear”. I don’t believe that it’s nearly good enough to shield these items from falling rain or snow, since there are lots of other ways for gear to become saturated. Walking through wet vegetation, for example, can sometimes soak a hiker and his/her pack even faster than a thundershower can. Likewise, on most trips (unless you’re traveling in the desert) there’s usually a good chance that you’ll need to ford rivers or streams and face the risks of either falling in the water, or having to ditch your pack if you get into trouble. So for me, the minimum requirements for keeping critical items dry include protecting them even in the event of a submersion that could last for several minutes.

Backpackers currently employ a number of strategies to try to keep critical gear dry on the trail, but regrettably, many of them don’t work very well under the worst conditions. Also, of increasing concern over the past few years has been the upsurge of interest in lightweight hiking which, in some cases, has prompted manufacturers to overstate the capabilities of their ultralight “waterproof” product offerings. It’s also caused some backpackers to make gear decisions that favor reduction of weight over functionality – choices that could ultimately have deadly consequences.

Below I’ve summarized a few popular gear protection techniques, along with reasons why I feel that each, when used by itself, is generally inadequate (with the probable exception of the Dana Designs waterproof packs discussed in the third section).

Image source: http://www.sportsmansguide.com/product/index/snugpak-aquacover-waterproof-100-liter-backpack-cover?a=1315224

Image source: http://www.sportsmansguide.com/product/index/snugpak-aquacover-waterproof-100-liter-backpack-cover?a=1315224

Pack covers:  A cover might help keep a pack from absorbing a lot of water during a downpour, but that’s about the extent of its value, in my opinion. I would never depend on a pack cover alone to keep critical items dry. Covers can’t protect gear from submersion, nor from the sometimes copious perspiration that can soak through the back of an internal frame (or frameless) pack. They also tend to snag easily on trail obstacles and can be difficult to keep in place during high winds. And once in camp, covers are not very useful for protecting items that have been removed from the pack.

In addition, to be fully effective, the seams of most pack covers need to be sealed by the user, and they must, of course, be removed in order to access gear on the trail. If you’re hiking somewhere that’s very wet (like the Pacific Northwest), pack covers might be OK to supplement other dry system techniques, but for most people on most trips, I believe that they’re largely a waste of weight.

Sea-to-Summit-Ultra-Sil-Pack-cover

Image source: http://www.campsaver.com/ultra-sil-pack-cover

Ponchos: Ponchos worn in such a way as to cover one’s backpack are, in a sense, a variation of the covers discussed above and generally suffer from the same shortcomings. The “Packa” is an interesting piece of gear that combines the function of a waterproof jacket with that of a pack cover, but likewise provides no protection from immersion.

Image source: http://www.tomwilson.com/2014/08/travel-gear-rain-jacket.html

Image source: http://www.tomwilson.com/2014/08/travel-gear-rain-jacket.html

Waterproof packs: A number of lightweight packs are currently constructed from silicone impregnated nylon (“silnylon”), which is said to be waterproof. As discussed in a previous article, however, silnylon’s water resistance is very limited, especially when subjected to the stresses of gear stuffing. In addition, this water resistance, according to my own tests, can also deteriorate significantly with use. Further, none of these packs will even start out “waterproof” unless the seams are completely sealed, a process that’s often difficult with a pack because of its complex structure. Other fabrics, such as polyurethane-coated nylons are also sometimes used for “waterproof” packs, but suffer from the same seam sealing problems. And of course, the closure mechanisms for these packs are usually not secure enough to protect the contents in the event of submersion.

One of the few packs that I might trust as my only defense against the elements is the Eureka Dry Doc, which is designed primarily for fishermen and paddlers. Because of its weight and design features, however, I’m not sure that this pack would be practical for normal backpacking.

Image source: http://uk.eurekaeurope.com/p/dry-doc

Image source: http://uk.eurekaeurope.com/p/dry-doc

Another very interesting design, however, was brought to my attention by “NotFrozen” on the Lightweight Backpacker forum after the original publication of this article. The Racer X and Raid Z packs from Dana Design are essentially dry bags with pack bodies wrapped around them. The smaller pack (Racer X) includes a 25L roll-top dry bag as the main compartment, along with other non-waterproof pockets that are built into the wrap-around clamshell harness. The larger pack (Raid Z) is similarly constructed but includes a 50L dry bag. Both dry bags include purge valves and can be either used with the pack or not, as conditions dictate. Likewise, either pack allows additional gear to be lashed to their sling-type frames to further increase capacity. Although these packs appear to be targeted mainly at adventure racers and ultralighters, they seem to be flexible enough to serve well for mainstream backpackers.

Update, May 2006: In 2005, Dana Design, which has been owned by parent company K2 since 1996, was merged into Marmot, also a K2 subsidiary. In connection with the consolidation of the two companies’ pack lines, the Racer X and Raid Z products have been discontinued, though some retailers may still have inventories as of this date.

Pack liners: If neither a cover nor the body fabric can keep contents dry, then about the only hope is to protect these items using a means that dwells inside the pack. Liners are one possibility, but they have their own set of problems. Some backpackers favor either conventional or compactor trash bags for this purpose, but I’ve found that even at 2 or 3 mils thick (1 mil = .001 inch), the polyethylene from which most are made doesn’t hold up very well on extended trips. Punctures from sharp objects, as well as the wear that results from the movement of the contents against the walls of the liners, tend to produce leaks fairly quickly. I used compactor trash bags as my primary protection mechanism for a while, but abandoned them after only a couple of outings.

Some pack manufacturers, such as Gossamer Gear, offer custom-fitted pack liners, but most appear to be made from the same kind of polyethylene as compactor bags, so although I have not yet tried them, I suspect they would suffer from similar durability problems.

Gossamer Gear Pack Liner Bag

Another option is to construct a liner from a lightweight water resistant fabric like silnylon, which I did a few months ago. Silnylon is tougher than polyethylene, but my recent research into its properties has caused me to lose confidence in its long term water resistance. Such a liner would, of course, also require seam sealing and is difficult to repair in the field.

One final problem is that most liners make accessing pack contents somewhat inconvenient. The tops of most liners must usually be twisted and tied off with a piece of cord or rubber band in order to make them reasonably waterproof. Having to deal with these closures on the trail every time something is needed from the pack is something of a pain.

Despite all of these issues, however, I do believe that liners can play a role in a well-designed “dry system”, but not as the primary line of defense. More on this point below.

Gear sacks: After years of trial and error, I now believe that the most sensible way to approach the problem is to use lightweight, roll-top gear sacks as the primary security mechanism for critical equipment, assisted by “half-pack” liners for non-critical items. The remainder of this article will discuss this approach… 

Stay tuned for Part 2. 

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