Corporal Si Klegg has made a serious miscalculation, his pack is unbalanced, heavy and has no hip belt. An excerpt from Corporal Si Klegg and his “Pard”, by Wilbur F. Hinman.
For
soldiers of the late 19th century, the biggest problem with the
knapsacks they carried, was how the weight of the knapsacks fell near the back
of their necks and shoulders, shifting their center of gravity backwards. This forced them to
bend a little forward to bring their center of gravity back over their feet. Bending forward, and the fact that all the
weight of the soldiers’ knapsack hung from their shoulder straps, except with
the Merriam pack, which had a partial hip belt and a frame to transfer some of
the weight to the hips, made marching tiring.
And
as we discovered in last week’s article, HERE,
in our modern world, just like in those days gone by, where you put the things,
and what you have to carry it in, is as important as how much weight you are
carrying.
Center of
gravity
Your center of gravity shifts depending on what you do or carry, drawing by the Author.
Your
“center of gravity” is the point in or OUT of your body, at which your
whole body and what you are carrying and wearing, balance. A line drawn through your center of gravity perpendicularly
downward, connecting your center of gravity with the center of the earth, is called
the “line of direction”.1 Your
center of gravity is the point at which your upper and lower body weight is
balanced over your feet, and it shifts with changes in your posture, body
weight, activity, and what is being carried, and where.
When
standing erect, with your arms at your sides, your
center of gravity is at a point about 56% of your height up from the
ground. If you’re a man standing erect,
this is usually a point slightly above your belly button, opposite your second
lumbar vertebrae, and about two to three inches, (five to seven cm) in front of
it. If you’re a woman, it is just below your
belly button and halfway between the lower back and belly.2
An excerpt from Well’s Natural Philosophy: New Edition, 1879
Since
your body’s natural center of gravity is just above your hips, if you load the
weight of your backpack or knapsack over your shoulders, your center of gravity
shifts upwards and to the rear, and you will start to tip backwards. To regain your balance, you will have to bend
forward, tensing your muscles, and shifting your center of gravity forward to a
point outside of your body.
An excerpt from Well’s Natural Philosophy: New Edition, 1879
When
walking on a level surface, your center of gravity shifts forward, compared to
a standing position; just as when walking uphill, or upstairs, it shifts even
further forward, to a point outside of your body; and when walking downhill, or
downstairs, it shifts it backwards, to a point behind your body.
The soldier’s center of gravity and how it shifts backwards to a point behind the soldier, as more weight is carried on the shoulders, an excerpt from Manual of Military Hygiene, page 255.
As
Dr. Valery Harvard wrote in the Manual of Military Hygiene, 1909, “...the
center of gravity of the load and that of the body should correspond as closely
as practicable ( Fig. 94). This is best
accomplished by distributing the weight around the body over as many points as
possible; such distribution has the further advantage to bring all available
muscles into play without overexerting any special set”.3
The
weight of your equipment when carried, to be properly balanced, should be as
near to your line of gravity (“x” in the illustration above), and as
close in height to your center of gravity as possible.
When
the pack you are carrying or the activity that you are performing, such as
walking uphill, causes your center of gravity to shift far forward or backwards
from your body’s natural center of gravity, the constant tensing of your
muscles will cause you fatigue.
Which soldier is standing straighter and has a center of gravity closer to his line of gravity, the soldier with the M-1910 knapsack on the left, or the one carrying the blanket roll on the right. An excerpt from “The Lessons of Our Past Wars”, The World’s Work, February 1915, by Frederick Louis Huidekoper.
Getting the
right backpack and adjusting it today
An excerpt from “How to Size and Fit a Backpack”, by REI, HERE.
First
off, you need to get the correct size of backpack and hip belt, and to do that you need a partner measure the length of
your torso and the distance around your hips.
To find the length of your torso,
first find the 7th cervical or the C7 vertebrae, which is at the
base of your neck, and the top of your hip bones, or your iliac crest. The C7 vertebrae is the bony
bump, where the slope of your shoulders meets your neck, that you feel when you
tilt your head forward to put your chin on your chest. The C7 is close to the collar of your tee shirt
when your chin on your chest.
To
find your hip bones, slide your hands down your ribcage to the top of your hip
bones, and with index fingers pointing forward and thumbs pointing towards your
spine, and have your partner trace an imaginary line between your thumbs to the
lumbar portion of your spine. While
standing straight, ask them to measure from your C7 vertebra down to this
imaginary point on the lumbar portion of your spine, across from your hip bones.
In
any case, remember to make sure that the padding is long enough to cover your
hip bones. If there is too little padding,
then the weight of the pack will not properly transfer from your shoulders to
your hips.
For more information go HERE.
Now
that you have the right size of backpack and hip belt for your torso and waist
size, you need to adjust the side compression straps (if any), the hip belt, the
shoulder straps, the load lifter straps (also known as load-adjuster or
stabilizer straps), and chest or sternum strap, so that the weight of your pack
is evenly distributed on your shoulders and on your hips, and the weight of the
load is brought in line with your body’s center of gravity.
The parts of a backpack, an excerpt from Royal Eagle Road website, HERE.
The
website for Royal Eagle Road trekking packs has a great section on adjusting
your backpack to that the load is as close to your body’s natural center of
gravity as possible. For more read “Trekking
Backpack Guide: How to Adjust Backpack Shoulder Straps, Hip Belt and Load
Lifters”, HERE, but
here are some highlights.
· Tighten
the compression straps to compress the backpack and to keep it from shifting.
· Next
with the backpack supported on an elevated spot, such as a log, rock, or table,
lean forward to adjust the hip belt so that it is just above your hip bones. If the hip belt is too high it will be
uncomfortable for your stomach, if it is too low, too much weight will be on your shoulders, and it will be in your way when walking.
· After
adjusting your hip belt, come back to a vertical position and adjust your
shoulder straps, so that they are tight.
· Pull
the load lifters until they are 45o from the horizontal. Tight load lifters pull the weight forward
and up, closer to your center of gravity, and provided better stability on
rough trails.
· The
chest straps keep the shoulder straps in place and help distribute the weight
of the backpack.
Packing your
backpack...
An excerpt from the 1970s era “How To Travel Light”, from Camp Trails, talking about how to pack a backpack.
So
how do your pack your backpack or knapsack so that its weight is evenly
distributed on your body and as near to your center of gravity as possible?
Backpacks
with frames, either internal or external, work best when low density, bulky
items, like sleeping bags, are squeezed into the bottom compartment, or securely
strapped to the bottom of the pack frame, over the hip belt. Bulky, but light gear, like cook kits or
clothing go in the lower and middle portion of your pack. Heavy items, like food, and your tent, should
go into your pack at shoulder height and as close to your back as
possible. On top of all of this, just
under the pack flap, or in an outside pocket, pack your first aid kit, your
rain gear, a flashlight, toilet paper, etc.
For
more on packing backpacks and knapsacks, read “Knapsacks and Rucksacks ©”, HERE,
and “How Heavy is Too Heavy? ©”, HERE.
So, hopefully, you won’t make the
same a serious miscalculation that Corporal Si Klegg made. Hopefully your pack will be balanced, no heavier
than it has to be and will have a hip belt
Don’t forget to come back next week and read “Building a WWII
Emergency Sustenance Vest, Type C-1, Part Two©”, where we will talk about what went
into pockets one, two and three and why they are important for survival.
I
hope that you continue to enjoy The Woodsman’s Journal Online and look for me
on YouTube at BandanaMan Productions for other related videos, HERE. Don’t forget to follow me on both The
Woodsman’s Journal Online, HERE,
and subscribe to BandanaMan Productions on YouTube. If you have questions, as always, feel free
to leave a comment on either site. I
announce new articles on Facebook at Eric Reynolds, on Instagram at
bandanamanaproductions, and on VK at Eric Reynolds, so watch for me.
That
is all for now, and as always, until next time, Happy Trails!
Notes
1 From,
Well’s Natural Philosophy: New Edition, 1879, pages 36 to 45, by David A
Wells,
2
From the Manual of Military Hygiene, page 257, by Harvard Valery
3
From the Manual of Military Hygiene, page 257, by Harvard Valery;
30 Minutes of Everything; “Where is Your Center of Gravity”; and from “Equilibrium Considerations for the
Human Body”, Physics in Biology
and Medicine (Fifth Edition), Paul Davidovits.
Sources
30 Minutes of Everything;
“Where is Your Center of Gravity”, [© 30 Minutes of Everything], https://30minutesofeverything.com/where-is-your-center-of-gravity/#:~:text=Your%20center%20of%20gravity%20is,slightly%20above%20the%20belly%20button,
accessed December 2, 2022
Atlas
Packs, “How to find the right size”, [© 2022, AtlasPacks], https://atlaspacks.com/products/hip-belts-included-with-packs,
accessed December 10, 2022
Buck,
Albert Henry, MD, Editor; A Reference Handbook of the Medical Sciences, Volume 5, [William Wood and Company,
New York, NY, 1902], pages 798, https://books.google.com/books?id=JpQplgCyEC0C&pg=PA797&dq=weight+%22blanket+bag%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiwz9mRodz7AhUhKFkFHfBsAF4Q6AF6BAgFEAI#v=onepage&q=weight%20%22blanket%20bag%22&f=false, accessed December 2, 2022
Carus, Paul, Editor; The
Open Court, Volume 39, [Chicago, The Open Court Publishing Company, 1925], page
478, https://books.google.com/books?id=YbdZAAAAYAAJ&pg=PA478&dq=%22center+of+gravity%22+walking+uphill&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjwnJD_mO37AhVdLFkFHSgRBg04ChDoAXoECAcQAg#v=onepage&q=%22center%20of%20gravity%22%20walking%20uphill&f=false,
accessed December 9, 2022
Davidovits, Paul; “Equilibrium
Considerations for the Human Body”, Physics in Biology
and Medicine (Fifth Edition), [Academic Press, 2019], https://www.sciencedirect.com/topics/physics-and-astronomy/center-of-gravity, accessed December 2,
2022
Harvard, Valery, MD; Manual of Military Hygiene, [William Wood and
Co., New York, NY, 1909], pages 255 to 257, and 261 to 264, https://books.google.com/books?id=DlA3AQAAMAAJ&pg=PA262&dq=%22field+equipment+of+the+U.S.+infantry+soldier%22+1909&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjhq_G74Yv7AhUJD1kFHf8cDEcQ6AF6BAgHEAI#v=onepage&q=%22field%20equipment%20of%20the%20U.S.%20infantry%20soldier%22%201909&f=false,
accessed November 29, 2022
Hinman, Wilbur F.; Corporal Si Klegg and his “Pard”, [The N. G.
Hamilton Publishing Co., Cleveland, Ohio, 1895], page 160, https://archive.org/details/corporalsiklegg00hinmgoog,
accessed December 1, 2022
Huidekoper,
Frederick Louis; “The Lessons of Our Past Wars”, The World’s Work,
February 1915, Vol. XXIX, No. 4, [Doubleday, Page &
Co., 1914 , 1915], page 398, https://books.google.com/books?id=y5zNAAAAMAAJ&pg=PA398&dq=%22it+weighs+nearly+ten+pounds+less+than+the+old%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjD5rq14Iv7AhVHF1kFHf8LAdQQ6AF6BAgHEAI#v=onepage&q=%22it%20weighs%20nearly%20ten%20pounds%20less%20than%20the%20old%22&f=false,
accessed November 29, 2022
Marquardt, Will; “Easy
Guide for Measuring Backpack Torso Size”, March 20, 2017, [© OutdoorsGeek], https://www.outdoorsgeek.com/backpack-torso-size/,
accessed December 10, 2022
Panico, Benjamin; “How to
Wear a Hiking Backpack”, November 11, 2022, [2020 Resort Outfitters], https://www.broadmooroutfitters.com/how-to-wear-a-backpacking-pack/,
accessed December 9, 2022
REI,
“How to Size and Fit a Backpack”, [© 2022 Recreational
Equipment, Inc.], https://www.rei.com/learn/expert-advice/backpacks-adjusting-fit.html,
accessed December 10, 2022
Royal
Eagle Road; “Trekking Backpack Guide: How to Adjust Backpack Shoulder Straps,
Hip Belt and Load Lifters”, [© Royal Eagle Road
2020], https://royaleagleroad.com/how-to-adjust-a-backpack/,
accessed December9, 2022
Wells,
David A.; Well’s Natural Philosophy: New Edition,
[New York and Chicago, Ivison, Blakeman, Taylor, & Company, 1879], pages 36 to 45, https://books.google.com/books?id=fLMAAAAAMAAJ&pg=PA44&dq=backpack+%22center+of+gravity%22+%22bending+forward%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiQneuwkO37AhV8hnIEHfdKDd4Q6AF6BAgHEAI#v=onepage&q=backpack%20%22center%20of%20gravity%22%20%22bending%20forward%22&f=false,
accessed December 9, 2022
Werner,
Philip; “How to Fit a Backpack”, March 26, 2022, [© Copyright 2007-2022, SectionHiker.com
and Fells Press LLC], https://sectionhiker.com/how-to-fit-a-backpack/,
accessed December 9, 2022
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