hey everybody Katie with REI here today we are going to be talking about how
much fuel to bring on a backpacking trip this is a really common question and
something that's really tricky to guesstimate and something I've been
wanting to do for a very long time so today we are going to do an experiment
and get to the bottom of it for science
all right so first things first in order to figure out how much fuel we need to
bring on a trip the first thing we have to figure out is how many boils we're
going to need to do over the course of that trip so if for example I'm going on
a three night solo backpacking trip I'm gonna need to boil water for three
rehydrated meals for dinner and three hot drinks in the morning I attend a
cold breakfast so that doesn't need to factor in for me but in sum for my three
night trip I'm going to need to boil six total boils your average rehydrated meal
is going to take 500 milliliters half a liter or two cups of water and my hot
drinks in the morning are about the same so each boil that we're going to
calculate here is 500 milliliters of water
so for each 500 milliliter of water we're going to figure out how much fuel
it takes to boil that amount of water we can do a little bit of math at the end
of the video here to extrapolate if it takes X amount of fuel to boil 500
milliliters of water how many total boils do we have in the can one caveat
here is that if you cook rice or pasta or anything that requires cooking time
rather than just boiling the water and pouring it in a bag to rehydrate as we
do the experiment here you're also going to look at burn time for one boil
alright so in our experiment today we are trying to figure out how much fuel
it takes to boil a half liter of water we're gonna go ahead and do that by
weight this is a 100-grand canister of fuel and that 100 grams refers to how
much fuel is in here but for this experiment to work we actually need to
get the total weight of the fuel and the container it's in so you can do this by
using a kitchen scale at home or this handy-dandy dangly scale that I have
here so this one and I'll turn this around for you in a moment
looks like 217 grams for the fuel and the container it's in so we're gonna go
ahead and write that down 217 grams is our total starting weight
so as I get this set up here we're gonna talk about a couple of caveats to the
experiment we're doing number one is that these are ideal
conditions when you go out into the field those conditions are going to
change and it's good to keep that in mind but our ideal conditions today will
give us a baseline to calculate off of the other thing to keep in mind is that
this experiment is going to give us numbers for this particular stove this
is just an old MSR stove I have it's a couple years old but if you're doing
this experiment at home by all means use your stove your fuel so that you get
numbers that are most accurate for your gear setup the last thing that think
about here is science though it may be we are not being super precise with what
we're doing here today so this is about 500 milliliters of water and when we
boil this water here I'm gonna set a timer going and I'm gonna start and stop
the timer about when the water boils but I don't have a thermometer in here
telling me exactly when it hits the right number of degrees to be boiling
I'm just looking for rolling bubbles so keep in mind there's a margin of error
but that being said let's get this experiment going alright so we've boiled
our water we let this cool down a little bit but since we've got our numbers here
we'll start with this in order to boil our half liter of water here it took us
2 minutes and 12 seconds so for one boil we have 2 minutes and 12 seconds of burn
time now what we want to figure out is how much fuel it took to boil that 1/2
liter of water so in order to do that since we weighed our fuel canister
beforehand we're gonna weigh our fuel canister again and see what numbers we
get so our canister now weighs 209 grams which means we used 8 grams of fuel in
our process to boil 1/2 liter of water now we can do a little bit of math we
know that this canister when it's full and brand-new has a hundred grams of
fuel in it if we divide a hundred grams of fuel by eight grams used for one boil
we get 12.5 so that means that this canister has 12.5 total boils of worth
of fuel in the canister there I'll tell you a secret while you weren't looking
we actually did this experiment and through an entire can of fuel as it
turns out our number of 12.5 boils per hunter grande canister was pretty
accurate we got 12 full boils of a half liter of
water and on the 13th boil the fire sputtered out part way through before
our water was done so 12.5 boils we could also do a little bit of math with
our time to figure out how much burn time is in this canister so since it
took us 2 minutes and 12 seconds to do 1 boil we can multiply that number by 12.5
to get the total amount of burn time in this canister ideally the thing to keep
in mind is that this is an unregulated stove and so what that means is as you
do each successive boil as the fuel depletes in this canister the pressure
of the fuel in the canister also decreases which means it takes a little
bit longer with each boil to get your water boiling so if you were using a
regulated stove our numbers here 8 grams of fuel 2 minutes and 12 seconds of burn
time times 12.5 in this entire canister would be pretty consistent all the way
until the canister was done all right so conclusions we got 12.5 boils out of
this 100 gram canister of fuel but remember that's in ideal conditions when
you go backpacking when you're out in the field their conditions will not be
ideal that's the fun of it but just to play it safe we're gonna go ahead and
say there are 10 solid boils in this 100 gram canister of fuel if we think back
to that hypothetical 3 night solo backpacking trip in which we need six
boils in order to have hot food and hot drinks every morning for 6 boils if we
go this canister has ten solid boils in it this one single small hunter gram
canister will do just fine for our trip if you're like me and you have lots of
partially empty canisters laying around in your gear bins go ahead and check out
some of our next videos to figure out how much fuel is in that half empty
canister until then have fun and we will see you next time