[pct-l] Bag/Quilt Warmth

[CHUCK CHELIN]

Good afternoon, Ned,

*The PCT Hiker’s Handbook* section on sleeping bags, Jardine’s paragraph on
Loft Degradation says:

*“Reduction of loft is a major consideration with sleeping bags.  The first
time you ram pack your new sleeping bag into its stuff-sack it loses perhaps
8% of its loft.  Forever.  Those imprudent enough to use a compression sack
can bid an additional 10” goodby.  That 18% loss is the damage incurred
during the first occasion.  Add another 3% for each subsequent hyper
compression.” *

Following his stuffed-but-not-compressed formula, a down bag with 3” of loft
would be 2” thick after 12 days, 1” thick after 34 days, 0.25” thick after
81 days, and less than 0.03” thick at the end of a 150-day hike.  Add the
compression loss everyday and the final thickness becomes 0.02”.

Like much of what Jardine writes I believe only about half.  While I
certainly agree that compression, or even stuffing, is a bad idea I don’t
believe his percentages.  I suspect Ray pulled those numbers out of his
exhaust system to illustrate a point.  I don’t have actual thickness
reduction numbers based upon experience, but my impression is the loss will
be more like 25% over 100-150 days of having been moderately stuffed.

Steel-Eye

-Hiking the Pct since before it was the PCT – 1965

-http://www.trailjournals.com/steel-eye

-http://www.trailjournals.com/SteelEye09


On Tue, Jul 26, 2011 at 11:26 AM, <ned at mountaineducation.org> wrote:

> Here's a related question...
>
> Has anybody thought about how a bag used from the start, about a month in
> at
> KM, since it has been compressed daily for all that time and gotten dirty
> and oily during nightly use, will have a worse temperature rating than when
> they started and this is at the very place where hikers need a bag rated
> for
> colder temps as they go up into the high sierra snow?
>
> Might be a good place to bring in a new, colder rated bag?
>
> Have any previous thrus noticed that they were sleeping colder once they
> left KM and before they hit the snow because the nighttime temps were
> colder
> there?
>
>
>
> "Just remember, Be Careful out there!"
>
> Ned Tibbits, Director
> Mountain Education
> South Lake Tahoe, Ca. 96150
>    P: 888-996-8333
>    F: 530-541-1456
>    C: 530-721-1551
>    http://www.mountaineducation.org
>