A non-scientific study

Obtaining water while on a winter adventure is relatively easy; all you need to do is melt a little snow or ice. Keeping that water in a liquid state is a bit more difficult. Although it's true that one can simply stuff the water bottle deep inside their sleeping bag, due lack of easy access they rarely, if ever, stop and dig it out. The best solution to this problem is an insulated water bottle parka that can be attached to the waist belt of the pack.

With too much downtime between trips and a well stocked gear closet, I decided to run a few comparison tests to determine which parka performed the best under controlled conditions. Each test consisted of filling a 1 liter (32 ounce) Nalgene lexan bottle with boiling water and placing it in a freezer that maintained a constant 8°F temperature. The bottle was checked after seven and eighteen hours and the water temperature and amount of liquid water was recorded.

Manufacturer	Price Average U.S.	Weight of parka	Temp at start of test	Temp after 7 hours	Temp after 18 hours	Liquid water after 18 hours
Uninsulated Nalgene bottle	$  6.50	NA	174°F	34°F 22 oz. liquid	NA	Frozen solid
Lowe Alpine bottle holder	$12.00	2.5 oz.	172°F	44°F	34°F	18.0 oz.
Wigwam Wool socks	$  6.50	3.0 oz.	174°F	48°F	36°F	20 oz.
Homemade bottle parka	$  3.00	1.75 oz.	174°F	62°F	34°F	24.5 oz.
The North Face botle parka	$20.00	3.5 oz.	174°F	62°F	34°F	24.5 oz.
Outdoor Research bottle parka	$15.00	4.0 oz.	174°F	68°F	34°F	26.0 oz.
Olam -15°F sleeping bag	$66.00   in 1978	5 lbs. 12.5 oz.	174°F	104°F	54°F	32.0 oz.

1 - The Lowe Alpine bottle holder is marketed as a "Waistbelt Bottle Holder", not as an insulted parka. The bottle holder is constructed from a high density foam with a bottom and sides but does not have a top. As the results show, this has a major impact on heat retention.

2 - Two moderately used Ragg Wool socks were pulled over the bottle and while they did help slow the rate of heat loss, they were so stretched out of shape that they were no long usable as spare socks.

3 - The homemade parka was made from a .5 inch thick closed-cell Polyethylene foam sleeping pad. Silver duct tape was used to secure the bottom and several layers were wrapped around the entire unit. Care was taken to avoid the stigma of wrinkles in the tape. A short piece of .75 inch webbing was added to serve as a attachment loop and a short length of accessory cord was used to secure the lid. The unit also performed well in a field test.

4 - A bottle was inserted into the center of an Olam 78 -20°F PolarGuard synthetic fill sleeping bag which was contained in it's stuff sack. The bottle added even more bulk to an already overstuffed sack. With some difficulty the entire unit was then placed in the freezer.

Ron Gizzo kindly allowed his North Face bottle parka to be used in the study.

Rich Fawcett has patiently tolerated the abuse I've heaped on his Olam 78 sleeping bag. And stove. And pack. And... well, you get the idea.

Winter Water - Drinking plenty of water is always important when in the backcountry. Without enough water, the blood becomes thicker, increasing the chance of cold related injuries such as frostbite and hypothermia.

Nalgene Wide-Mouth Loop-Top Bottles - Available in economical white or super-tough, transparent smoke gray, the convenient wide mouth and permanent graduations allow easy measuring of liquids. Guaranteed leakproof, the easy-opening, "captive" cap never gets lost.

Outdoor Research Water-Bottle Parka - It won't make a water bottle perform as well as a vacuum bottle, but it only weighs a few ounces, can be stuffed in a pack pocket, and won't be damaged if it gets dropped two pitches up! Insulated with low-conductivity urethane foam, the holder fits over 1 liter (32 ounce) Nalgene bottles. The outer fabric is waterproof Hydroseal and zips closed with a coil zipper.

Lowe Alpine Waistbelt Bottle Holder - The insulated Waistbelt Bottle Holder attaches to any pack waistbelt to carry a 1 liter water bottle within easy reach. A drawcord top prevents heavy bottles from going ballistic when you swing your pack on or off.