Number of boils from a gas camping stove

[bikenerd]

I'm trying to work out how much gas I need to take with me on a camping trip, which will last 3 days, cooking twice a day, boiling a litre of water each time.
My stove is a Coleman F1 lite.  It has a gas outflow of 346 g/hour.  It takes 3 minutes under ideal conditions to boil a litre of water.  So, if we say that the boil time is 4 minutes under windier conditions, that is 0.0666 of an hour, which will use 0.0666 * 346 = 23.06 grams of gas.
If I take a 100g gas canister, will I really only get 4 boils from it, or is my logic flawed?
Does anyone have any experience using the smallest (100g) gas canister and a small stove like the Coleman or a MSR pocket rocket?

Cheers, Neil

[mark]

Your math matches mine, so under the exact conditions you tested in you should get 4 boils. Gas flow will quite likely slow down as the container runs low, and boiling time will increase in colder temperatures and with colder water.

Windier conditions can stretch the boiling time quite a bit, so bring a good windscreen like the ones MSR offers for their liquid fuel stoves (sheet of aluminum wrapped around the pot and stove, basically.

If nothing else, a larger canister would provide a more stable base, reducing the chance of the stove and pot tipping over.

[andrew_s]

Wind can make a lot more difference than the extra 30% you allowed for. It could easily double, and could even treble.
When using windscreens on gas stoves, you want to ensure that enough air gets in at the bottom for efficient combustion (CO poisoning if in enclosed space), and that the canister doesn't overheat (bang).

I generally reckon on about a week for a 220g canister. Morning tea, pre-dinner tea, meal, post dinner tea, using about 400ml for tea and whatever it takes for the meal.

Where does the 346g/h flow rate come from? If that's full blast, to match the 3min boil time, you are wasting a lot of heat up the side of the pan. You will get better value turning the wick down a bit.

[bikenerd]

Where does the 346g/h flow rate come from? If that's full blast, to match the 3min boil time, you are wasting a lot of heat up the side of the pan. You will get better value turning the wick down a bit.

That figure is from the manufacturer's spec, not something I've measured and I guess it is max flow rate.  I cook with a mini-Trangia pan, so I wouldn't be using the full blast of the stove as, as Andrew says, the heat would be lost up the side of the pan.

The question is really: I'm going hiking in the Cairngorms for 4 days, should I take a 100g or 250g gas canister?