[pct-l] figuring canister use

[rickbb at sonic.net (Rick Beebe)]

A couple of years ago I tested various stove options (Esbit, alcohol, 
canister) and came up with some data on canister fuel usage which you might 
find interesting.  My canister stove is an MSR Superfly, and in the testing, 
I used a small Snow Peak canister, which contained 3-1/2 ounces of fuel (the 
canister weighed 7 ounces full and 3-1/2 ounces empty). A 1-cup boil plus a 
separate 2-cup boil together reduced the weight of the canister by 1/2 oz, 
which is to say that they required 1/2 oz of fuel. I got eight 1-cup and 
seven 2-cup boils on the 3-1/2 ounces of fuel in the canister. So figure 
each ounce of fuel in the canister is going to boil roughly six cups of 
water. Look at your food plans, figure out how many cups of water you're 
going to want to boil each day, and take it from there.
My real-word experience seems to bear this 6 cups/fuel ounce ratio out: on a 
600-mile AT section hike several years ago, I got roughly 5 days on average 
out of a large MSR canister boiling a *lot* of water (probably 10 cups a 
day). Using the rule above, to boil 50 cups would require about 8 ounces of 
fuel, which sounds about right for one of the large MSR canisters (I have a 
full one in the garage that weighs 13 ounces).

Re the altitude issue you raised, I did the above test at 750 feet altitude, 
outdoors but in relatively protected conditions.  After the test, I used a 
canister stove on a thru-hike of the JMT, and although I didn't keep careful 
track, I don't think the altitude made a huge difference.  I suspect that 
whether or not you effectively shield the flame from any breeze would make 
much more of a difference in the long run.

--Snowbird