Monday, February 1, 2016

Custom SAR Pack Project: Intro, Cutting Foam




For those of you who don't know, I've been an avid backpack enthusiast for about the last six years. During that time, I've been on a neverending hunt for the 'perfect' pack for Search and Rescue. However, I've been consistently disappointed. I've tried offerings from Mystery Ranch, REI, Mountain Hardwear, Granite Gear, Gregory, Osprey, and others, and I could never seem to find a pack I was entirely happy with.

Most recently, I took a cheap, basic, top-loader internal frame pack from Eagle Creek that I bought used, and treated it as a 'project pack.' I got closer with that rig than with any previous ones to something that really worked to my satisfaction, but it still isn't quite there (pictured above).


The root of the problem is this: I want a pack that's relatively lightweight, but with enough of a suspension system that it isn't going to trash my shoulders if I have to carry extra SAR-related equipment, such as a Stokes litter, a long climbing rope, various technical gear when assisting the local tech rescue team, a cardiac monitor/defibrillator, extra water, extra food, extra clothing, or whatever else.

Industry packs with a substantial suspension system sufficient for the occasional heavy loads of team gear and/or 12-to-13 hour missions tend to be 'deluxe' backpacking packs, built with high-denier nylon, and festooned with zippers, pockets, and stuff that is mostly added to wow the casual shopper, and has no real utility. True, I want pockets in front of me for oft-used items like a GPS, but behind me, I just want a big bag I can fill with stuff sacks, possibly with a small lid pocket for lights and gloves. The deluxe-style packs have far more pockets than I need, and thus excess weight of material and zippers.

Conversely, ultralight packs offered by the industry tend to really skimp on suspension comfort. Since they're designed for backpackers who only carry 15-25 pounds of gear, carrying a SAR load plus a litter and/or any of the items listed above starts out as uncomfortable and quickly graduates to painful. Thus, what I really need is a deluxe suspension married to an ultralight packbag. As far as I can tell, such a thing does not exist. So I've set out to build my own, with those parameters, in bright orange, and as streamlined as possible without compromising function.

This will be something of an experimental testbed of a pack. I'm trying a lighter material than the cordura nylon I'm used to working with, I'm trying a concept with a single 50" zipper that wraps around the whole pack instead of having multiple separate access points, I'm using a simpler concept for the sternum strap, and I'm going with an integrated top pocket instead of the floating lid on top of a cinch collar that I've had on the majority of my packs in the past.

So far, I've spent about $65 on material. I think I have everything I need to build a pack that should be comparable to a $200-350 industry pack. For the pack body, I'm using a 1.6 oz ripstop nylon, with 2.2 oz PU coated nylon in certain high-wear areas like the bottom panel. I decided to go with 1" webbing and hardware rather than the 3/4". 1/2" or even cord-based compression systems popular with ultralight bags, simply because I already have a couple dozen buckles, 100 yards of webbing, and various other hardware in 1", so changing sizes would drive the cost of the project way up.

For the shoulder straps and hipbelt, I'm using foam from a USGI closed-cell sleeping pad. While they're not great to sleep on, the foam is durable, and soft enough to use for pack straps while still being stiff enough to provide some support. Some of the ultralight backpacker forums I looked at recommended specific foams, but I've been satisfied with the performance of this stuff in my Eagle Creek Frankenpack, so I didn't see a reason to spend money on something different, since I had this sitting in my garage already.

On to the first step of the project itself; cutting foam. I cheated a little on the shoulder straps; I'm basically just duplicating the straps off the Frankenpack, since I made those from scratch and I've been happy so far with their performance. You'll notice that the strap is not a straight piece of foam; they're contoured outward to go around the neck, and then back inward to allow the arms to reach forward.


You'll notice on the shoulder straps and hipbelt, I've worked with the curve of the foam, cutting it so that they curve the way I'll want them to curve when I'm wearing the pack. This sleeping pad I'm using as a source has been rolled up in my garage since I was 15, was rolled up on a shelf in a surplus store before that, and was rolled up in some Army warehouse before that, so it's probably been rolled up since before I was born. If you're working with a piece of foam that's taken a set like that, you can either work with it, or you can fight it the whole way.

The little 1.5" x 3.5" foam blocks above the hipbelt are the padding that will sit between my back and the plastic frame. It's an idea that I nicked from Granite Gear's Nimbus pack, (image below), and was the only that came to mind of allowing airflow and reducing weight without foam molding equipment I don't have access to.

Image: http://www.utahoutside.com/2014/08/granite-gears-new-packs-at-outdoor-retailer-2014-summer-market/ 
Now, when cutting foam for a project like this, I wouldn't recommend rounding off the edges of the foam, at least not on the hipbelt. If you have the time and patience to do it by hand on the shoulder straps, more power to you I guess, but on the hipbelt, that sharp corner to the foam helps the pack to grip your iliac crest and not slide off your ass. That tendency to slide down is one reason I don't still own the Granite Gear pack pictured above.

That's all for now. As I accomplish further steps, I'll post more. The next major step will be covering the hipbelt and shoulder straps.

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