Saturday, April 30, 2011

Saving Time with a Bushwalking "Thermos"

Ever wished you didn't have to light your stove in the morning just to make a hot drink? Ever had hot water left over after your evening meal that you have wasted? Does you cup serve more than one function? When its raining, have you ever wished you didn't have to go outside your tent to light your stove?  Ever wanted to sleep in for another fifteen minutes but didn't have the time? Like to pack your tent in a leisurely fashion without worrying about your tea/coffee getting cold? Save time with an insulated vacuum  flask and add very little extra weight.
Zojirushi Tuff Slim Stainless Steel Vacuum Bottle
The solution to all these problems is a "lightweight" stainless steel vacuum insulated flask which can be pre-heated and filled with hot water the previous night and will still be warm the next morning. With a wide-mouthed flask you can soak your dehydrated food in hot water during the day and have it ready for dinner or have hot porridge for breakfast. No longer do you need to get up fifteen minutes earlier to light your stove just to boil one or two cups of water, and then wait for it to cool down before you can pack it away.

Intuitively a "thermos" would seem like an additional, unnecessary piece of equipment to take on a bushwalk,  but is it really? It can replace your mug (135 g) and maybe one of your smaller water bottles (100g), so it is not all added weight.  Some fuel can be saved each morning, which would otherwise have been wasted heating the stove and billy and your valuable "sleep-in" time increased. If you are using a wood campfire then the time saving is even greater. Get cold feet at night, then here is you solution?

Heat Retention

Use a spare sock or stubby holder to increase insulation and reduce heat loss. On a cold night use it as a foot warmer in your sleeping bag. With these tricks and pre-heating, I have managed to maintain coffee at the standard McDonald's temperature of 60°C for over 12 hours. This is a little cooler than usual coffee connoisseur's range 155ºF/70ºC - 175ºF/80ºC but its OK for the bush. Unfortunately, smaller flasks cool more quickly than large, so most bushwalkers are starting with a size handicap. The easy pour lids that allow you to pour by pressing a button or lifting a tab seem to lose heat faster so try to avoid these and instead select one with a screw top. Take the claims on the flask boxes and their websites with a "grain of salt" as many have been proven to be grossly inaccurate. If you have the opportunity to compare flasks and don't have a thermometer, touch the outside; the one that is hotter will cool the fastest.

Well regarded brands include:
  • Sigg Thermo Trend (.3L, .7L, 1.0L) which will supposed keep water hot for 14 hours
  • Thermos Thermax Light and Compact (0.47L/325g, 0.75ml/475g, 12hrs) They also have Thermos TherMax Ultimate Flask 0.5L Graphite at 310g which is supposed to keep hot for 24 hours.
  • Aladdin (apparently has won some comparison tests, but many have had trouble with under performance with the 1L Stanley model)
  • Zojirushi Tuff-Slim (0.5L/450g) 167°F/75°C @ 6 hrs. / 117°F/50°C @ 24 hrs. Rating is based on water at a starting temperature of 203°F (95°C) at a room temperature of 68°F (20°C). Zojirushi have been specialist vacuum flask manufacturers for ninety years.

    They also make the 12 oz (0.35L) Zojirushi Stainless Steel Mug (SM-CTE35) with built in Tea Strainer. A great idea for Chai tea or if you don't like tea bags.
Amazon.com Product Description
This Zojirushi Stainless Mug comes with a tea strainer that allows you to brew fresh tea right before drinking. It features vacuum insulation to keep beverages hot or cold for hours, nonstick interior for easy cleaning, 2-inch wide mouth (easily accommodating ice cubes), detachable and easy-to-clean tea strainer with handle, and a secret compartment on lid for tealeaves and teabags. The screw-tight lid provides better heat retention compared to commuter mugs, and prevents leaks. The body can be washed under running water, but the bottle should not be soaked in water. It's backed by a 5-year warranty for heat retention. 
      Wide-mouthed flasks
      You might like to consider getting a wide-mouthed flask which is more versatile, easier to eat from and clean, but is less well insulated and slightly heavier. Good examples come from Zojirushi eg the Tuff-Mug SM-AFE35 (12oz/0.35L/450g wide-mouthed (5cm) thermo,  which can keep water at 181F (81°C) for 1 hour or 140F (60°C) for 6 hours). Rating is based on water at a starting temperature of 203°F (95°C) at a room temperature of 68°F (20°C) The Tuff-Mug has room for storage of a teabag and a non-stick interior for easier cleaning. Some mention that wide-mouthed flasks are more difficult to drink from and that you may need a cup too, but in the bush this is a luxury most will do without.

      Zojirushi Stainless Steel Tuff Travel Mug

        Creative Commons License   This article by Bush Walker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

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