>> True, but we were trying to equalize the thresholds for ease of attaining a pack that light  not ease of carrying it.
Well then we're talking about subtly different things. I sort of thought it would encompass a bit of both, ideally, since the whole point of going UL is to have a pack that is easier to carry. But, yes, after some thought I will agree that what you are saying is a more accurate characterization of the whining that we hear from the sasquatch people.
I will graciously concede. :o)
So, I guess we have to figure out a way to flatten the slope a bit? Any ideas on how to do that? Bearing in mind that we must have sound theory to back up whatever mechanism we come up with?
I guess that what we should do is survey 10pound base weight packs of 5'10" individuals and see what percentage of the weight is considered "height dependent". Then we can further modify the formulae. For instance, if we decide that half of the average pack's weight is height dependent, then we can construct a formula that ignores half of the difference in height between the standard hiker and the actual hiker. (I actually think I can figure out how to do that...)
Who's up for performing the survey? :o)
Also, speaking of geekoff:
I was unhappy with the artificial origin of the 'standard Avoirdupois hiker' height, so I looked up some true average heights... Average human height worldwide is, coincidentally, 4'11" or so. But I didn't think that basing the PWI formula on that was really in the spirit of the thing since most of us are admit it western males.
So, ignoring extremes of age the average western male height seems to be about 5'10" or so. (The Swedish are a little taller, the French are a little shorter, etc.) With this as the height of the standard hiker the constant in the PWI formula should be 490, rather than 500, to make the average hiker's 10pound pack result in a PWI = 1.
500 nonetheless results in a pretty good SWAG, and is easier to remember. But the "official" constant is now 490.
I could, of course, develop a similar constant for the PMI to correct for average height. As a matter of fact, if I'm going THAT far I could also make the constant such that a 5'10" hiker with a 10pound pack produces a PMI = 1, so that it is identical to the PWI...
Do think it's worth the trouble? Or should I keep the metric formula "clean"?
EDIT
Well, heck, it actually wasn't much trouble. The PMI constant would be 0.701, which I suppose we could round to 0.7 to make it easier to remember. We'll call that the "normalized" PMI, eh?
Actually, I guess that if I'm being intellectually honest then the PWI formula above is "normalized", too. I have adjusted the nomenclature in that first equation appropriately. Without the constant (be it 500 or 490) the Avoirdupois formula produces some very cumbersome numbers. (Even if you use feet instead of inches, UL is defines as about 0.3.) At least the nonnormalized PMI formula (without the constant) produces wieldable numbers, as long as we are willing to concede the 5'8.5" 'standard metric hiker.'
I really like setting UL at unity, though! :o)
I will go further and clarify that unless otherwise specified, PWIn means BPWIn and PMIn means BPMin, and that by definition these ALWAYS factor in any item that is neither worn nor actually held in the hands while hiking, but including the weight of the actual pack, and less consumables. Thus, the gram weenies can't cheat on their BPMIn/BPWIn by having stuff in their pockets!
I invented it, so I can define it however I like. So there! :o)
So, now the normalized PMIn and normalized PWIn should be equivalent, with UL defined as unity. Or, you could multiply by another factor of ten, to produce a Height Adjusted Pack Weight Equivalent (HAPWE). In such a case, UL = PWIn x 10 = 10. Get it? It will produce a number equivalent in pounds to the weight of your pack for a 5'10" person. Then you can use whatever definitions you like for UL, SUL, or whatever. HAPWE may be cumbersome to calculate, but everyone will understand the value produced intuitively.
Yeah. I think I'll run with that...
Somebody please check my math. Better yet, somebody produce a proof that the two equations are equivalent... :o)
Edited by acrosome on 08/19/2009 13:19:03 MDT.
