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View Full Version : Estimating Food, Time, Distance.



JAK
2007-06-24, 12:56
I've got this new idea for estimating food, for a given trip, or alternatively for estimating time for a given trip. It might seem oversimplified, but I am wondering if it might work for most people once it is calibrated with better data. It works something like this:

FOOD[lbs] = (DISTANCE[miles]/12 + GAIN[km]) x WEIGHT[lbs]/200

where:
FOOD = weight of food in pounds
DISTANCE = distance travelled in miles
GAIN = cummulative elevation gain in kilometers
WEIGHT = average weight of hiker plus gear plus consumables

Most notably it doesn't worry about how fast you are travelling, or how long you are stopping each night, or how fit you are or even how much body fat you are burning. It assumes you are travelling at a pace that is about right for you, but that you are more intent on covering distance than camping too much along the way. Campers might add a pound of food per day, which they tend to do anyways. The reason I think it might work well is those of us that are overweight tend to travel slower and perhaps rest longer and so we probably burn more calories when stopped relative to the distance we travel each day, but we also tend to have more fat to burn and more time to burn it, so I think these two things tend to cancel out. The other assumption is that the food is about 3-4 kcal/gram, or 1300-1800 kcal/pound. Again, fitter people might have less fat to burn, but they can include more fat in their diet which increases the kcal/gram, so it might work out even, more or less.

Anyhow, the same formula might be used to estimate how much time a segment might take. Most people eventually figure out how much food they are capable of eating each day. For most people it might be 2 pounds/day, but for naturally larger people, or even smaller people well trained, this could go up to 3-4 pounds or more. So instead of estimating food for a given leg, based on estimated duration, you might be better to estimate the duration based on the estimate of food requirements for that segment.

e.g.
60 miles with 5 km cumulative elevation gain.

Hiker#1
220 pounds of hiker, gear, food, water, on average.
say this hiker needs 2.2 pounds/day at their prefered pace.
FOOD = (60/12 + 5) x 220/200 = 11 lbs of food
TIME = 11/2.2 = 5 days (12 miles/day)

Hiker#2
150 pounds of hiker, gear, food, water, on average.
say this hiker needs 2.5 pounds/day at their prefered pace.
FOOD = (60/12 + 5) x 150/200 = 7.5 lbs of food
TIME = 7.5/2.5 = 3 days (20 miles/day)

Would this simple formula work for most people with some tweaking? Is there a database available with hiker weights and food consumption for various segments of the Appalachian trail, or other trails or trip reports?

JAK
2007-06-24, 13:25
The other thing that might be done with this formula, once calibrated, is that someone might be able to use it to estimate how far they might be able to travel starting out with a given load of gear and food and body weight. Again, they don't count the fat burned as food since it only cancels out the calories burned while resting and sleeping, but it does effect the weight carried. Little more complicated but not much. What is less predictable is the first few days of full load, if you over do it, so we will keep it reasonable.

Hiker#1 = 145 pounds lean body mass.
Terrain averaging 1km cumulative gain per 10 miles travelled
180 pounds start, 160 pounds finish, 170 pounds average
20 pounds of non-consumables
60 pounds of food start, 0 pounds finish, 30 pounds average
Total Weight = 220 pounds average

DISTANCE/12 + DISTANCE/10 = 60 x 200/220
DISTANCE = 297.5 miles

sailingsoul
2007-06-24, 16:53
JAK ! Your talents maybe wasted on some but not me . I'm with you, keep up the good work..... I do have 2 questions about your formula. Shouldn't the values all be either metric or standard not both. Like Miles and Weight in metric or Gain in feet? And what is the reason for dividing miles by 12 ? I do like the new thread. One never knows what benefit will be had by asking questions and exploring concepts. This is excellent. SS :captain:

JAK
2007-06-24, 19:43
Thanks. Sometimes I think sobriety is wasted on me. Yes it probably should be all metric or English I suppose. I guess it depends on what sort of map or data you are working with what sort of units you should use. As for the coefficients, I have a nasty habit of fudging numbers so they work out to even integers. I must have been a Pythagorean in a former life. I will try to find more data, then come up with a final emperical formula, for others to play with and fudge for themselves of course.

Seeker
2007-07-22, 01:59
dude, you've got way too much time on your hands... :albertein

what if you just go somewhere, and then take a zero day once you get there. no miles, but you still need food.

i just go with 2lbs a day/person. i actually break it down to individual meals when i plan, but it comes out to about 2/day.

but if you insist on continuing to do the math that mixes english and metric measurements, just remember to add 20% more time, distance, and weight when camping in canada. something about the exchange rate... maybe turk can chime in here... :D

Seeker
2007-07-22, 02:23
for example,

1) if HOI is watching Seeker scraping magnesium off Turk's firestarter block to add to their alcohol stove fuel, using Iceman's small 4" knife, from 6 meters away, how long will it take for seeker, turk, and iceman to blow themselves up?

or,

2) given the above scenario, but while the action is occuring in canada, HOI is safely across the border in, say, minnesota.

or,

3) combining both scenarios but asking how many fingers will Seeker lose in the process?

in most cases, all measurements must be converted first into english (if in the US) or metric (if in canada). in the case where the observer stands in one country and the action takes place in the other, it doesn't matter. the border guards on both sides are pretty mellow, so you can just 'average' it out by using neither system. you fall back on the old-style swags (thumb length, cubits, nose-to-middlefinger length, feet (use Turk's. Iceman's throw the average WAY out of whack), time estimates, and degrees Kelvin. that way everyone's happy.

by the way, the answers are:

1) We don't know. Seeker's wife stopped them before they got hurt. But we've have had a pretty good fire going there in another couple minutes...

2) We still don't know. Probably about as long as it takes to down a Sam Adams, a Molson, and a couple shots of Wild Turkey.

3) Just 1. But if we staple it back on, maybe add a little duct tape, it won't matter.



anyone remember where we put that thread on the possibilities of nuclear, magnesium, and alcohol powered ION stoves?

(if you still don't understand, neither do i. note the time and chalk it up to sleep deprivation).

no alcohol was involved in the creation of this entry.

Take-a-knee
2007-07-22, 02:24
JAK can't help himself, he's an engineer. Glad to see you back around these parts Seeker.

Seeker
2007-07-22, 02:28
good to be back, thanks. work's been busy, haven't been out in the woods since march, and now it's almost too hot out to go hiking...

hey, you were a medic, right? maybe you can figure out the part about how to put a finger back on... just kidding. sometimes i have no idea where stuff in my head comes from...

jimtanker
2007-07-22, 05:05
JAK - I like the idea. Great stuff.

Now we need someone who is an Excel guru to do up a worksheet for this to do the auto calc. Actually two sheets, one for metric and one for the real world.

JAK
2007-07-22, 06:17
LOL. I tried bringing an excel worksheet into the field with me, but got a nasty shock and burn when I tried to use it as TP. :nurse:

Iceman
2007-07-22, 11:07
JAK, you are supposed to light it AFTER you wipe, not before.

Seeker, are you sure there was no alcohol involved, must have been impaired by something !:biggrin:

Besides, why all the concerns about attempting to predict what you are going to need, or eat, or spill on the ground, or leave in the freezer at home, or burn in your pot, BEFORE a hike? Sort of takes the fun out of it! Not me, my contingency plan includes enough extra grub to start a Zoo or UN feeding station or similar. Oops, sorry, didn't mean to associate these two...

jimtanker
2007-07-23, 09:04
We need a new entry into the Lexicon.

Iceman - the opposite of ultralight