Approximately how much alcohol would I need to bring on a 33 day trip boiling 1.5 liters of water a day in a .9L pot?

I'm actually thinking about switching from my trusty Pocket Rocket to the cat can.

The amount of fuel you will need to carry depends on the fuel efficiency of your stove.
If you have to carry all the fuel you will need for 33 days it would be a better weight savings to carry your pocket rocket and the equivalent fuel.

It would depend on your stove. Fire it up and see how much fuel is required to boil a full pot, and then try to calculate that in to how many meals you plan on preparing.

Kinda depends. Altitude, temperture, set-up.
Anywhere from about 1.5floz per day or for 33 days, call it 50 fl oz or about 42oz.
To about 3floz per day or cal it 99floz for 33 days. It will weigh about 82oz. This allows a couple ounces for the container(s.)

Thats 5 pounds of fuel (holy crap) I've never had more appreciation for my little wood burning Ikea stove.

this calculator may help some

http://www.howardjohnson.name/Backpacking/Stove/Stoves.htm

Yeah, I'll stick with my Pocket Rocket.

There are some graphs on the zenstoves sight comparing the weight efficiency of various types of fuel systems: http://zenstoves.net/StoveChoices.htm

Interestingly, the "best" (lowest total weight) system varies depending on the number of meals cooked.

I picked up a Caldera Cone in late July last year and a clearance REI ti .9 pot. I ran it a few times at home and it used around 5/8 - 3/4 oz. denatured alcohol to boil 12 oz. of water. Time was over 7 minutes if I remember correctly. Consistant times also and I was using lake water most of the time. So run your stove at home a few times and see what it uses, I live at 4,000' and bped around 9,600' and higher last August for eight days. Last year was the first time in 7 years? my Pocket Rocket was left at home for a vacation bp trip. The PR uses a small MSR canister up in 8 days, boiling 12 oz. water in the evenings and maybe water for one morning instant oatmeal.
Duane

As others have indicated... it depends on conditions and the stove/windscreen design, and type of pot - wide short typically ~20% more efficient that tall narrow. My experience would suggest that you will need between 1-1.5oz/day (doing 2 .8l boils) assuming a good windscreen and good stove to pot distance).

Build / buy the stove, try it at home with water you have chilled down to the temp you expect it to coming out of the river/lakes you will be pulling it from and maybe a fan to simulate wind. Then take it out into the field to verify your lab experience. There seems to be a lot of variation in efficiency.

That said, if you are doing .8l a boil, my experience is that any decent alcohol stove (or esbits) - a properly constructed cat stove fits this - ends up being lighter than iso butane when you factor in carrying the empty canisters. If it's 33 days without resupply I will second the recommendation using one of the stoves that can burn wood.

--Mark

I agree with Mark. Canisters and Alcohol stoves are about the same overall weight after factoring in the canister weight. There really isn't any difference in weight.

WG is more fuel efficient, with burning about 3/4-7/8oz per day with a SVEA on low. But the stove is much heavier, off-setting the weight savings in fuel. But the bulk is reduced by about 30ci. You can pack a little more food in that. . . at least to start.

Alcohol stove performance is heavily affected by a multitude of external variables. That makes it very hard to nail down real world performance in a controlled setting. My advice would be do practice with the alky stove in a variety of conditions to develop a good "feel" as to how it will perform in real life.

I don't know what your day to day life is like, but if you work, maybe bring it along and cook your lunch on it or make your breakfast before work, etc... Do a couple of shorter trips where you can bring extra fuel along as a safety measure.

To improve consistency you need to isolate the stove (burner unit) from outside conditions as much as possible. That means use a rock solid windscreen (TD Caldera Cone, for example, or a high walled cylindrical setup) and try to insulate the stove from the cold ground. The temperature of the surface the stove is sitting on has a massive affect on the rate of alcohol vaporization. I've been experimenting (not very scientifically) with using a piece of corrugated cardboard wrapped in aluminum foil. The aluminum foil reflects IR radiation, and the corrugations create a small dead air space between the stove and the ground. I don't have any quantitative data yet, but it seems to be a bit of an improvement.

BM

Yes, many, many variables. With my alky, I use 1oz per day for my water needs. For 33 days, I could fit all I need in a 1L Platy which takes up much less volume and weight in my pack than the canisters would. Not to mention that volume would decrease over the trip while canisters won't.