Overstuff existing bag?

[Jesse Anderson]

I have an REI sub-kilo I bought a few years ago that I really like but doesn't quite keep me warm enough as I get into the shoulder seasons. There is plenty of baffle space left in the bag and I would like to overstuff the top of the bag, leaving the underside in it's original state.
So here's the crux of my question, how much down should I plan on using to moderately overfill the top side of a sleeping bag? Not sure of the original fill rating, but I'd probably use ~800 fill to do the overstuffing.

[Justin Baker]

Western mountaineering won't overstuff my bag more than 2 oz, hopefully that helps.

[John Smith]

I love this bag too, and have used one for years. It is time for major work on it to bring it back to standards and maybe even a bit more.

As for your bag, I would venture a guess that you have lost loft in your bag so you may be able to get far more loft into it than a WM bag. WM bags typically fill their baffles fuller than the sub-kilo did when new. SO I am guessing another 4 oz wold be good, I know it would work in mine.

[Steven Adeff]

I looked into this a while ago and the general consensus I read was that 10% over the standard fill gets you roughly 5F gain in insulation and that beyond 35-40% it's diminishing returns.
so see what you need as far as an increase in insulation vs the added weight you are willing to accept.

I'd bet Tim Marshall has some good thoughts on this, might be worth contacting him and asking?

[David Franzen]

adding down to a bag: You will pick up ~2.6F for every ounce of 850-fill that you add. http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=27480&skip_to_post=227472#227472

There is another post by Richard Nisley where he progressively overstuffed a sleeping bag. IIRC, warmth returns did not start to diminish significantly before overstuffing by 100%(probably because the percentage of fabric weight, which does not add significant warmth, decreases). unfortunately I can not find the link any more.

edit: found the link: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=16189&disable_pagination=1
see post on 10/13/2008 21:13:15 MDT

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