The Physics of Hunting Pack Load
By Kurt Racicot, SG Founder & Lead Designer
When you shoulder a loaded pack, gravity wants to win. Everything on your back is pulled down to the trail at your feet. You are the only thing keeping it upright. This tension creates leverage, causing us to lean forward and engage our core to maintain balance. The more leverage you endure, the more energy and effort it takes to move down the trail.
While you are not going to eliminate gravity or the actual weight of your pack, you can manage the amount of leverage (i.e. strain) the weight puts on your body. There are three key factors to address for carrying a heavy load efficiently with a Stone Glacier Pack, which we'll detail in this blog: load placement, load lift, and load migration.
We can’t pack out those elk quarters for you, but with a little applied physics, we can show you how to make your load feel lighter.
Load Placement
Years ago, I built a pack load simulator to illustrate that how you load your pack makes a huge difference in how heavy it feels on your back. By simply packing the load properly, you can cut the amount of leverage in half.
In this simulation, I used six sandbags for a combined weight of 76 pounds to represent a healthy load of meat. The platform on which the bags sits measures 12 inches wide by 11 inches deep, roughly the size of many 6,000 cubic-inch bags, and it represents your pack. The vertical pole is your back.
Kurt's original load simulation setup.
Simulation one represents a load that spans the full dimension of the bottom of a backpack. This simulates loading all the meat, the heaviest and densest portion of the load at the bottom of the pack not using a load shelf. As a result, this load generated around 32 pounds of constant force (leverage) tugging at your torso, shoulders, and neck. The only way to compensate for this leverage is to lean forward and engage your core while trying to navigate terrain.
In simulation two, notice how the weight is stacked higher along the back. This simulates loading meat or heavy gear onto the Load Shelf featured in every Stone Glacier Frame and cinching it to the frame using compression straps. In doing so, the amount of leverage is reduced to just over 14 pounds.
When packing, I place the lightest gear on the bottom, farther away from my torso. The heaviest items are packed as close to the pack frame as possible. I typically place dense loads such as sheep horns or any skull with a cape under the pack's lid, as close to the frame and my back as possible.
Load Lifters
Load placement is a large part of the hauling equation, but it’s not everything. Stone Glacier packs are built with integrated load lifters, which are the straps that leave your shoulder strap and climb to the top of the frame. Stone Glacier frames have a load lifter height of 26” and provide a mechanical advantage that reduces leverage of the load that pulls you back. The secondary function of the load lifters is to stabilize the load, which is key when traveling tough terrain under a load.
Check out this video to see how to adjust a load lifter properly:
Load Migration
After you’ve taken the time to pack the load, the last thing you want is to have that load wiggle itself free. Hiking off a mountain with a heavy load that is unstable is a recipe for injury. The terrain is uneven, but your load shouldn’t be. Load shift is an easy risk to mitigate thanks to compression straps.
Stone Glacier packs feature enough straps and buckles to secure any load. The best way to understand how these compression straps work is to see them in action. This meat packing tutorial walks you through the process.
The next time you’re about to pack out a heavy load, keep in mind that you’re never going to escape gravity. Be smart about how you pack. Reduce the amount of felt leverage by packing heavy items close to your back and go up, not out. And remember to utilize load lifters and compression straps.
It’s not exactly rocket science, but there is a science to efficiently packing out those heavy loads so you can hunt confidently in the backcountry and safely get the goods off the mountain and onto the tailgate of your truck.
