We went down several design avenues when selecting the right pack for an expedition like this.
It all came down to what sort of pack would be most appropriate for a route and environment like this. So, let's start with key features of the route, and location/season, that might affect pack selection:
- It's going to get wet. A pack that absorbed as little water as possible, and was as effective as possible, at keeping water out of the packbag, are desirable features. This is a wet environment. It rains a lot, we're camping on wet ground, and we have dozens of rivers to cross - some that require swimming. The pack needs to keep the contents dry.
- It needs to carry weight. We're humping 50+ pounds of food, and a little bit of gear, at the beginning. The pack also needs to be "soft" enough so as not to inhibit mobility while moving fast with very light loads towards the end, for our highest mileage days.
- It needs to adapt to variable load volumes. This criterion alone elimintaes most of the packs on the market, which are poorly compressible in large volumes and don't generally carry gear on the outside well in larger volumes. All the gear needs to fit inside the packbag (for river crossings), yet the packbag must be adaptable to a rapidly shrinking load volume as the trip progresses. In other words, a small load must also result in a small pack (in contrast to a small load carried poorly in a big pack) in order to maximize our efficiency and comfort for high mileage days and rapid pace towards the end.
- It must provide immediate access to all essential gear used throughout the day without having to access the packbag. That means we need to be able to reach two liters of water and 2000 calories of food without taking off the pack, and being able to grab wind and rain gear without opening the packbag. The goal here is twofold: we don't want to waste time dealing with gear, and we don't want to expose gear inside the packbag to the elements unnecessarily.
This criteria led the development of custom "dry bag harness" packs by ULA Equipment, affectionately and informally denoted as the "ULA Arctic Dry Pack". The packs are based on a design by Roman Dial for Alaska trekking and packrafting, and implemented in various forms in the past by Dana Design and Cascade Designs, and since then, pretty much "upgraded" to a state of dysfunctionality in some form or another by these and other manufacturers (or in the case of Cascade Designs, discontinued altogether).
The ULA Arctic Dry Pack integrates two key components: a dry bag and a harness.
About the Dry Bag. We have selected the Pacific Outdoor Equipment 65L Pneumo Dry Bag (12 oz / 340 g) for our packbag. We tested so-called ultralight dry bags from other manufacturers, including Outdoor Research (seal not waterproof under immersion, outer fabric absorbed significant quantities of water) and Sea to Summit (neither seals nor seams waterproof under immersion, poorly durable fabric*). The POE Pneumo proved to be completely waterproof at its closure, seams, and fabric, even under significant immersion pressure. It also offered slots at the bottom of the bag through which compression straps could be threaded to cinch a heavy load into the lumbar region of the pack harness. Finally, it comes with an air exchange valve, which is a very nice feature for (1) compressing the packbag as much as possible while hiking for best load stability, and (2) inflating the packbag for river crossings to improve flotation and minimize the net pressure of water against the packbag fabric during immersion.
* The Sea-to-Summit Ultra-Sil Dry Sacks deserve a fair assessment here. First, they are not designed or intended to withstand the water pressures of immersion. They are intended to provide rain protection to gear while packed inside a backpack. Ryan will be using Ultra-Sil Dry Sacks inside his main POE pack dry bag for his sleeping bag, insulating clothing, and satellite phone electronics.
About the Pack Harness. The ULA Arctic Dry Pack offers the following features, and weighs 24-30 oz (depending on size and other options):
- Dry Bag Compression System. One outer harness, one top cinch strap, and three sets of side cinch straps for securing the dry bag to the pack harness (see image to right).
- Replaceable / Customizable Back Pad. Can be adjusted to accomodate variable types of padding and frame stay configurations. For example, Ryan's backpad is constructed of a dual density foam and twin frame stay sleeves for load transfer.
- Wide, but Thinly Padded Hip Belt & Shoulder Straps. To maximize surface area for load transfer without inhibiting movement or binding under heavy weight (see image below).
- Large Hip Belt Pockets. Each pocket can hold 1,000 or more calories of food (see image below).
- Rear Mesh Pocket. Rear mesh pocket has three openings (center and two sides). Side openings have elastic drawcord closures and are accessible while wearing the pack. Perfect for water bottles. The center opening can be used to stash clothing, more food, or trekking poles. (See image to right).
- Bear Spray Holster. Shoulder strap offers a bungee system for securing a can of bear spray.