Gear Selection: Bear Canisters

The two of us have degrees in engineering so when it comes to selecting and optimizing our gear we often draw on that background to help with the selection process.    When gear is purely performance based with less dependence on comfort or fit then it lends itself to that kind of selection process quite well.

Why Use These Methods to Select Bear Canisters?

While there is certainly some “soft” or immeasurable requirements in bear canister selection, they are generally dominated by stats and numbers.  The main requirements for a bear canisters are:

  • low mass (minimize)
  • acceptable cost (threshold)
  • high or acceptable volume (threshold)
  • meets regulation (binary – yes or no)

These are pure numbers and can be optimized and used in the selection process.  In addition to those requirements you should also take into account the following:

  • ease of use/ difficulty to open
  • security against other animals (not bears)
  • ease to pack

These are generally what I would consider to be immeasurable.  You can’t really grade these parameters in an honest, non-subjective way. As engineers we try, but we almost always acknowledge how much of a “fudge factor” these provide.  I like to take these case by case and not fool myself with grading these values.

Collecting Data

So to use the data to rank the canisters, first you actually need the data.  This is pretty simple to do. Most websites have this information available.   When they are not available you can pull data from product reviews or even buy something, weigh or measure it, then return it.

We collected the below data on some bear canister options.  We limited our selection to canisters that we could purchase reasonably easily as well as canisters that were likely to be approved to be used on the trails we plan on hiking.

Table of Bear Canister Data

Table of Bear Canister Data

Criteria

Already partially covered above, we have some requirements and some criteria for selection:

  • Low mass (minimize)
  • Cost should not be above $150 per unit
  • Be capable of carrying a week (5-7 days) of food for two people at a time
  • Be allowed to be used on the JMT

Selection

To select the bear canisters we generated a few plots of some parameters based on the criteria.

Mass per Cost vs Capacity

Mass per Cost vs Capacity – Minimize Mass/ Cost for Capacity Above 10 days

Starting with the capacity, we put together some combinations that could make sense based on the size of our packs.  Then mass per cost is plotted against capacity.  By minimizing the mass/ cost ratio for canisters with capacities above 10 days, this let us count how many options we have.  The above plot is a little simplified, but we could continue to put together combinations of canisters to get enough combinations that meet the cost, mass and capacity requirements. In the above plot, the orange X satisfies these requirements the best. The blue dot meets the capacity requirements but isn’t the best for the mass/ cost ratio.

 

Cost vs Mass per Volume

Cost vs Mass Per Volume – Both Parameters Should be Minimized

Next we plotted cost vs mass/ volume.  For this you want to minimize cost as well as minimize the mass/ volume ratio.  As you can see, as mass decreases the cost increases. This is to be expected. When evaluating this curve we want to ride the curve as far left as possible without going above our total cost requirement (approximately $150).  Then that option needs to be evaluated against the capacity requirement above.

On this plot, the orange X certainly has the lowest mass/ volume ratio but it also has the greatest cost.  Unless we can sort out the extra cash this is no longer an option.

CONCLUSION

When evaluating both plots together the blue dot is the option presented that has the lowest mass/ volume ratio while having a capacity above 10 days and a cost below $150.

The blue dot in the above charts represents combining both BearVault canisters (BV500 & BVSolo).

Of course the above charts hide a few decisions made based on the “soft” requirements, but they still guided us in making an informed decision.  We had to take into account availability and lead times (we purchased our bear canisters immediately before our PCT hike in 2014).  We also took into account the size of our packs, and general expectation of how fragile a canister could be if dropped.  Also, ease of use was considered. The BearVaults can be opened / unlocked by pressing firmly. Other canisters need a coin or screwdriver to open them up.  The BearVault also is transparent, allowing for you to easily see the contents. This is very helpful after a long day on the trail.

Overall we are pleased with our decision.  The Wild-Ideas Expedition (orange X above) was definitely the lightest per volume, but getting it cost $200 more than getting both BearVaults. That would have only given us a reduction in mass of 200 grams. Saving this money let us focus on reducing our pack weight even further by getting new sleep systems and upgrading other gear.

 

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