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michael coppens
(mtc)

Locale: midwest
alcohol stove vs jetboil weight on 04/24/2011 06:28:13 MDT Print View

doing 5 days with my son this summer -- generally speaking and based on our food plan, i will be heating about 12oz water - 6 times per day. (that's 2 coffees + 2 breakfasts + 2 dinners, daily) so this means 30 boils. i figure this would require around 24oz of alcohol plus "some extra", so say 30oz total. that's almost 2 pounds of fuel! at this point, i'm seriously considering just going with my jetboil for ease and speed? at what point does the lightweightness of an alchy stove lose its advantage?

John Jensen
(JohnJ) - F

Locale: Orange County, CA
Re: alcohol stove vs jetboil weight on 04/24/2011 07:19:23 MDT Print View

There are lots of charts, but these will be a start: Zen's Stove Choices

Will Webster
(WillWeb) - M
Zen chart on 04/24/2011 07:34:16 MDT Print View

The comments on the Zen chart indicate that empty canisters are assumed to magically disappear, but that empty alcohol bottles are packed out. Not really a fair comparison in my mind.

John Jensen
(JohnJ) - F

Locale: Orange County, CA
Re: Zen chart on 04/24/2011 07:41:59 MDT Print View

Well, for 30 boils it would be nice to assume some wood. Then alc or esbit + wood would really come out low.

Ken Thompson
(kthompson) - MLife
Re: alcohol stove vs jetboil weight on 04/24/2011 09:25:04 MDT Print View

What if you went with a regular canister stove and a larger pot so you could boil 24oz at once?

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: alcohol stove vs jetboil weight on 04/24/2011 10:37:10 MDT Print View

Well, so much is dependent on what you cook, how you cook, at what altitude, in what types of winds, type of stove, wind screen, and so on, I tend to ignore what other charts and graphs say except in extreamly general terms.

I look at basic fuel density.
A) heat per weight of fuel
B) weight of fuel carried per volume.

B) is easy. These generally run between .7 and point .8 for Alcohol, WG, isobutatane, or propane. I just use .75 and get close enough.

A) is a bit more difficult, but using the info from http://en.wikipedia.org/wiki/Heat_of_combustion

We find that
Methyl: 9,800 BTU/lb
Ethyl: 12,800 "
Butane: 21,700 "
Propane: 20,900 "
Gasoline: 20,400 "

With the liquid fuels we find that a 3/4oz soda bottle works as a container for about a half pound of fuel. Or, about 1.5oz per pound.
We call denatured alky about 10,000 btu to account for the methanol denaturing agent and the water from distilling it. Inexact, since it will vary from batch to batch, but always a bit more than that. The proportion of fuel to weight is 9.375%.
We see that we get about 9537.1BTU/lb carried. (??? 9375TU/lb)
(EDIT: for math errors)

With gas we need about 3.75oz (about average weight) per 4oz canister...
or about 15oz per lb of fuel. We call the fuel 20,000BTU/lb since it is Isobutanae, not butane, and it is mixed with 10% propane...roughly. (It depends on your canister.)
The proportion of fuel to weight is 93.75%.
We see we get about 10625BTU/lb carried. (??? 9375BTU/lb)
(EDIT: for math errors)

In conclusion to your question, there is no difference in fuel weights carried for any duration trip once you add in for the containers.
(EDIT: Not quite true. Close enough not to invalidate things. It depends on the canister. My first three sets of numbers all were bit more than 100% done with MSR 4oz canisters that weighed ~4.05oz empty. The last set was done on the fly using 3.75oz from a Primus canister...corrected. My apologies for the error, above.)

An 8oz canister is more efficient at roughly 6.5oz for ~8oz of fuel... One of the "depends" I was mentioning. But adding in for the stoves again changes the figures. As does the "step" functions for canisters.

BTW: Doing the same math for WG:
We call WG about 18,500 BTU/lb. (WG is NOT gasoline.) Adding a 1.5oz container gives us about a 9.375% proportion of fuel to weight, as with alcohol.
We see about 17632BTU/lb carried.
(EDIT: for math errors)

Note that only the stove weight really effects the calculations much. The UL alky stoves and foil windscreens (or Caldera Cone system) are my choice for short trips, ie less than 5 nights. For more than that I use a WG stove. When I first did these numbers several years back, I got a LOT of arguments. But, numbers don't throw BS at me. I gave away my canisters and canister stoves.

(EDIT: Same conclusion, my apologies, I blew my computer as I was trying to work up the numbers. Again, my aplogies till I can get a real one back up.)

Edited by jamesdmarco on 04/24/2011 19:45:13 MDT.

Kevin Babione
(KBabione) - MLife

Locale: Pennsylvania
Alcohol Vs. Jetboil Vs. Wood on 04/25/2011 07:21:52 MDT Print View

I just bought a Woodlore woodgas stove from Antig Outdoors to solve this very issue. I also own a Jetboil and two Caldera Cones (one for a 640 ml pot and a Compact CC for a 1 L pasta pot).

The Woodlore nests beautifully in my 1L Ti Pasta Pot and, depending on your alcohol stove, would probably make a very nice windscreen. My 12-10 stove doesn't fit inside the Woodlore but I am looking to find one that will to use as a backup in the unlikely event I can't find enough dry twigs.

For only $28 for the Woodlore stove you may want to consider one. For a 5-day trip I'd probably take my alcohol stove and enough fuel for a day (3 burns) and then count on twigs for the rest of the time. The Woodlore weighs 6.7 ounces - and that includes the base and the stuff sack.

Buck Nelson
(Colter) - MLife

Locale: Alaska
For two people I'd take the Jetboil on 04/25/2011 13:15:37 MDT Print View

That's my rule of thumb. If I'm hiking by myself I'll almost always bring an alcohol stove. If hiking with someone else, I'll use a more conventional stove. You get more heat per oz. of fuel with a Jetboil or white gas stove. With two or more people you're sharing the weight of the stove by splitting up gear. I'm not sure how the grams would actually break down, but at some point performance comes into play. The Jetboil gets it done right now and I suspect if you run the numbers it might actually be lighter for two people.

Diane Pinkers
(dipink) - M

Locale: Western Washington
alchohol stove on 04/25/2011 14:35:58 MDT Print View

I have a Caldera alcohol stove, and backpacking for 10 days last year with my boyfriend, that was all we needed. I *WAY* overestimated how much fuel we would use--I had 5 8oz containers, two we carried with and 3 we stashed partways along the way. Didn't need anywhere near that amount. I would fill the alcohol stove in the morning for a 2 L pot, getting enough for 2 hot drinks and 2 freezer-bags of oatmeal. In the evening, we tended not to drink hot drinks, so I only needed half that amount. I had made a major miscalculation, and thought that the little plastic measuring cup was 2 ounces, not 1 ounce, so I overestimated by almost double.

Mike Clelland, in his new book, had a great estimate for how much alcohol one would need per day per person. I'll let him chime in if he wants to, or encourage you to buy his book!

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: alcohol stove on 04/25/2011 15:20:20 MDT Print View

"and thought that the little plastic measuring cup was 2 ounces, not 1 ounce"

And all along I thought that it was a jigger measuring cup for liquor.

For one upcoming trip, for the number of days, for the amount of boiling I need to do, for the cool weather temperatures, for the weight of the various stove/burners and fuel containers... for everything added up, it turns out to be a wash. Alcohol and butane are about equal. The only fuel that has a slight edge (lighter weight) is Esbit. I'll almost have to change the duration of the trip to make the fuel decision easier.

--B.G.--

Mark Hudson
(vesteroid) - MLife

Locale: Eastern Sierras
jet boil on 04/26/2011 21:35:53 MDT Print View

I have done this experiment, for what you are going to cook, the jet boil wins for overall speed and carry weight.

You have to look at how much fuel the stove uses for a boil of the size you want.

but at some point an oz here or there for the speed and easy use, of a jet boil ... and you are cooking a ton.