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Re: How much fuel to melt snow for 1L of water?

Posted: Tue Apr 02, 2019 10:41 am
by limpingcrab
West to east april 15-21st.

Re: How much fuel to melt snow for 1L of water?

Posted: Tue Apr 02, 2019 2:23 pm
by bobby49
OK, I was comparing notes with my old snowcamping partners about white gas usage. Here is the conventional wisdom:
For a trip where you do not need to melt snow, then assume 1.5 to 2.0 ounces per person per day. When snow melting is done, double the fuel usage. However, that was the way that we did it using MSR G, GK, XGK, and XGK-II stoves. There are many variables, so you really have to do your own tests. For one thing, many campers consume a lot of fuel in stove priming. There are ways to get your stove priming very efficient so that there is very little wasted, and stove priming might be 10% of all fuel used. The efficiency of a wind screen is also important. I know that cooking inside a tent can be risky. However, it also helps a lot for fuel efficiency. If the heat shield and wind screens are tight, then that hurts you. If they are too loose, then that also hurts you.

Re: How much fuel to melt snow for 1L of water?

Posted: Tue Apr 02, 2019 2:24 pm
by bobby49
Compare all of those white gas data points to butane data points and see which one makes the best sense for a winter trip.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 9:31 am
by limpingcrab
I agree that white gas would be better but I don’t really want to buy a separate setup that I’d only use on two or three trips per year

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 10:45 am
by longri
I don't agree that white gas is "better". There are trade-offs. I'd personally take a canister stove.

The Jetboil is a little small for melting snow but it will work, especially Sierra spring snow which is going to be pretty dense in terms of water content. You could run the Jetboil inside the tent with a high safety margin. That's a bonus if the weather is funky. The weight of the empty canisters will be greater than empty white gas fuel bottles but for a 6 night trip it isn't a big deal. You can crush the empties, something you wouldn't do with the white gas bottles.

Anyway, it's a moot point since a Jetboil is what Mr. Crab plans to take.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 10:50 am
by longri
How much fuel to melt enough snow for a liter of water? Huh. If you can keep the stove out of the wind it should be on par with what it takes to boil a liter of very cold water, perhaps a tad more. My canister stove can do 6-7 liters with a 110g canister in the summer. That's 16-18g of fuel per liter of water. At home it only takes 10-14g for my stove to boil a liter, depending on how low I turn down the stove (lower flame = less fuel used). The Jetboil is supposed to be more efficient than a standard canister stove so perhaps it will do even better. I can't vouch for that or for its cold weather performance.

You know, you could sort of try it at home. Crush some ice and put it in the Jetboil along with a pinch or two of cold water. Weigh the canister before and after. Repeat it a few times. Then figure that it'll require a bit more in the field because of temperature and wind.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 11:12 am
by bobby49
longri wrote:
Wed Apr 03, 2019 10:50 am
How much fuel to melt a liter's worth of snow?
That was not the original question. I believe that he asked about fuel to melt enough snow to produce one liter of water.

If it is fluffy new snow, then it takes about ten portions of snow to produce one portion of water. If it is very old icy snow, then it takes about 1.5 portions of snow to produce one portion of water.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 11:26 am
by longri
Yes, that's what I meant. You knew it.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 11:31 am
by bobby49
longri wrote:
Wed Apr 03, 2019 11:26 am
Yes, that's what I meant. You knew it.
No, I did not. You wrote your words and I took them to mean exactly what you wrote.

Re: How much fuel to melt snow for 1L of water?

Posted: Wed Apr 03, 2019 12:19 pm
by longri
Either you're a liar or an idiot. Which is it? :-)