Behold the humble vacuum bottle. Nothing makes crawling out of your fart sack easier on a cold day then a warm cup of coffee brewed the night before and stowed in your boot within easy reach. Aside from everyday uses, a VB should be in everyone's ruck on summit day as part of the medical kit.
Testing VBs is one of the easier tasks at Gearflogger HQ, and not coincidentally one of the few things we do with anything remotely resembling a scientific method. Usually our testing looks a lot like a gorilla jumping up and down on a piece of luggage. While inebriated. And possibly brain damaged.
But... science! First we looked at weight and capacity of four different bottles:
- Hydroflask 64oz capacity, weighs 27.4oz = 2.3 wet to dry
- Hydroflask 40oz capacity, weighs 16.1oz = 2.5 wet to dry
- REI 16oz capacity, weighs 9.1oz = 1.8 wet to dry
- Thermos E5 20oz capacity, weighs 13.4oz = 1.5 wet to dry
We then put 165F water in each and tucked them in the back of the fridge for nine hours to see how well each retained heat. The envelope please:
- Hydroflask 64oz capacity, 137F = 83.0% efficiency
- Hydroflask 40oz capacity, 120F = 72.7% efficiency
- REI 16oz capacity, 133F = 80.6% efficiency
- Thermos E5 20oz capacity, 143F = 86.7% efficiency
So what do we conclude? First, all were plenty hot enough to enjoy after nine hours. Second, the Hydroflask 64oz bottle is the second most efficient for both capacity-to-weight ratio (2.3) and retained heat (83 percent), making it in our opinion the best option if there is more than one in your party and/or you just need to keep a lot of liquid at temperature for long, cold/hot days.
And forget about the mathy stuff for a minute; the 64oz is, after all, a growler, which means... beer! Thank you Hydroflask. And they're a very socially and environmentally responsible company, so cheers all around!