How much fuel to make water.

[Neil]

While on the subject of stoves can anyone give me a rough idea as to how much fuel it takes to melt snow to make a quart of water? Five of us are thinking about a 3 day range traverse and 6-8 qts./day each for drinking and cooking seems about right. Lets assume the snow is at 0 deg F and the water will be heated to 100 deg F. I'll be using a Primus vari-fuel and white gas.

 

[tonycc]

I usually follow the guideline from the MSR site for my Whisperlite International:

MSR recommends 4 oz. (114ml) of liquid fuel per person per day for cooking or 8 oz. (237ml) of liquid fuel per person per day for melting snow and cooking. An extremely cold trip, like skiing in Antarctica, may require as much as 15oz. (444 ml) of liquid fuel per day.

This has always been fairly close to what I really need, at least for winter and melting snow.

Tony

 

[bobmak]

In the winter I never cook, just melt snow. All the food I eat is instant (like Ramen, Fantastic food cups or freeze dried). If the snow is clean, I get the water hot but not to a boil. Once the stove gets going, it keeps going until enough water is ready for food and drinks. If I think I may want a hot drink after dinner, I'll store some hot water in a lexan bottle, put it in a bottle parka and stuff it into my sleeping bag; it'll stay hot for hours. Once the stove is off at night or in the morning, it stays off. I use an XGK stove, a 3 liter aluminum pot with a tight cover that is painted black and a home made wind screen that extends to the top of the pot.

All that being said, I am a fuel miser. By conserving fuel I find that a 22 oz bottle lasts for 4 meal days (2 people / 2 meals / 2 days). This is cutting it close for a weekend trip and does not offer a margin of safety in case you get stuck for a night out, so often I'll bring a 32 oz bottle and fill it with about 26 ozs of fuel. An added advantage to this is that a bottle with some space holds pressure longer than a bottle that is filled to the brim.

 

[carole]

I asked a similar question about a year ago...

More than you'll ever want to know about fuel needs

 

[NYBRAD]

Yup, in winter, 8oz a day per person is a good guide. I bring an extra days worth of fuel per person for multi day trips.

 

[Remix]

You people only drink 2L of water per day in the winter? Hmmmm....

 

[bobmak]

You people only drink 2L of water per day in the winter? Hmmmm....

I usally count on melting 4-5 liters per person per day. Between 1 & 1 1/2 liters to cook with and drink at the beginning and end of the day, and 2 liters to hike with. Usually at night I melt enough snow to fill up the bottles for the next day and in the morning I only melt enough to make a big mug (I think mine is a 22 oz) of coffee or tea and to rehydrate whatever breakfast stuff I am eating

 

[tonycc]

You people only drink 2L of water per day in the winter? Hmmmm....

Not sure where you concluded 2l per day. In the linked thread, wally2q test results were reported that melted/boiled water to fuel ratio is about 10 to 1. Thus, the 8oz per person per day guideline would yield close to 5 liters of water per person per day. That seems about right from my experience.

Of course, this is only if you have to melt snow for all your water. I try and get liquid water whenever possible, thus building a fuel reserve.

Tony

 

[wally2q]

water useage

It all depends on how many hours you remain active (per day), the rate of your activity, and the environment.

I've used the formula for alpine style climbing trips and have always been in good shape. My daily intake of water is 3.5L though (if you include the water used for meals). The 2L is just for "drinking". We usually run 10-12 hours of active work per day on our trips, but as you can surely appreciate, there is quite often a lot of variance in this.

Note that some people perspire more efficiently than others, some people overdress while engaging in physical activity (thus perspire more heavily), and some people have varying efficiencies of their cardiovascular systems.

Using myself as an example, I find that when I climb with a 45lb pack, crampons, axes, rope handling etc., I hardly ever breathe through my mouth (meaning - no need for high rate of O2 / CO2 exchange), whereas my partner breathes quite heavily. No difference between our performance or abilities - just a variance in our lungs I guess. What that means (I suppose) is that I loose a lot less water through breathing.

Your frequency & volume of urination, and color (density) is the best gauge on whether you are properly hydrated.

anyway - the purpose of the formula is to show fuel-to-water ratio, in below freezing environments. If you want to drink 5 or even 10L per day, you are more than welcome to. Just bring more fuel.

thanks,

the wall........

P.S. if you drink 22oz of coffee - no wonder you need to drink more water. coffee is a diuretic. I drink hot orange gatorade (0.5L bottle).. YUM!!!!, or hot chocolate..... otherwise it's cool water while on the trail.