Over filling a down bag

If things work out or whatever, is it worth getting, if available, a down bag over filled? I have heard you can order an over filled WM bag. I have been knocking around the idea of getting yet another WM bag, maybe a Summerlite and selling or using my Caribou as a car camping bag. I would really like a 30 degree bag, but not gain any weight over my Caribou 35 degree bag. If the Summerlite was over filled an oz. or two, is that going to compress the down too much? I see the WM Megalite, 30 degree bag has the same dimensions as the Caribou and I thought the Megalite was for bigger folks. I could live with the Megalite, but you know, always trying to shave more weight when upgrading. Any other 30 degree opinions that are less than a pound and a half? I don't want to sleep in my clothes using a half bag. I looked at FF last week. Off to the Winds later next week for a solo trip.

I can't address the overfill question, not having tried it. I'd be very hesitant to head for the Wind Rivers with a 30* bag, unless you are taking a down parka and pants with you to supplement it.

I take a 20* bag (WM Ultralight). I note from her book that Wandering_Daisy takes a 10* bag. Of course we women tend to sleep colder, but it is quite possible to have nighttime temps in the low 20's or even upper teens even in early August.

I'm looking forward (with envy) to your trip report!

I saw that about the 20 degree bag. I have an Apache, a 15 degree bag, no 20 degree bag. My logic is temps will be similar to the Sierra, I may bring my jacket instead of my down vest. I did see some photos that gforce on TT posted. They got snowed on.

I have not backpacked in the Sierra, but from the descriptions it sounds warmer than the Winds. Certainly the weather in the high Rockies is definitely more severe and more apt to be below freezing than in the high Cascades of Washington and Oregon. In the Winds you can get snow and temps down to the mid-teens even in midsummer. Last summer it snowed almost a foot in Titcomb Basin on Aug. 8 and again on Aug. 15. At Elkhart Park the morning of August 9, the temp was 20 degrees, and that's just the trailhead. In the Winds, you can expect a daily round of thunderstorms starting mid-afternoon. I don't believe that's true in the Sierra; I know it's not true for the Cascades.

Hopefully Wandering_Daisy, who is very familiar with both places, will chime in!

You could call WM and ask them about the warmth of an overfilled bag.

Three things (at least 3) happen on overfilling a down bag. The loft increases a little which adds warmth just from thickness. The down compresses a little which means the density goes up a little and that means that the thermal conductivity decreases a little which adds warmth. The weight of the bag goes up by the amount of overfill, and the warmth to weight ratio can be changed by an unknown amount. Oh, the cost goes up too.

Your best bet is to call WM and ask. Or, hear someone talk about personal experience. Or buy a bag made to 30F or 25F or 20F specifications.

Thank you OM, I'll at least bring my down jacket. The pictures gforce linked to showed his group hanging out with jackets on a few days. I was looking at the NOAA weather for Pinedale, days are cooler during the day than where I live and night temps about the same. Chance of thunderstorms all week. Can be that way here in the Sierra. I may use the Elkhart TH.

It probably depends on how much the standard fill, fills the chambers--loose fill will benefit more than packed fill. Bags with continuous baffles might benefit more from overfill than bags with smaller, divided baffles.

I could envision adding fill to my Ultralite because there's spare room to move down within the side baffles. I have an overfilled Dakota winter bag and it practically stands in the corner by itself. I never saw one with standard fill to compare.

Cheers,

I know Hermit's Hut in Redding used to offer a deal, free overfill on WM bags since they can't put them on sale. I wonder how other stores can offer them on Ebay. I picked up my WM jacket this winter on Ebay, a third off was my winning bid. Makes sense, some bags are better than others depending on how they were sewn.