Sleeping bag help

What does a 15 bag do that your 0 doesn't? Seems to me that if you're looking at temps well below freezing, it's matters little if you take the 0 and just vent it once or twice throughout the night.
A 30 with proper clothing will take me into the mid-upper 20's, and I'm sure as you approach the teens the 0 bag would easily cover the gap.
I guess if you were hell bent on a bag in that temp range, any of those would work.

Thanks Daniel. I'll have to try it out and see. I tend to get really hot in the 0F when it's 15F outside, though I have not tried the 30F bag at 15F to see if that direction would work well too.

If it turns out that I don't need a bag in the middle, I get to spend that cash of a lighter tent!

Kevin

agree w/ the above poster, I have a 15 degree bag (Helium) and also a 30 and a 0, if I was forced to get rid of a bag it would be the 15 degree bag- as said above if the rating is accurate for your 30 degree bag you could easily stretch it into the 20's and anything below low 20's could easily be handled by the 0 degree bag

my 15 degree bag is a luxury item :)

Obviously everyone is different, but I would think that using the 0F bag like a quilt would be perfect in the between temps. Just unzip it and lay it over you with your feet in the box. If you get hot flap a side, if you get cold roll it up and use it like a bag again. I do this all the time with my Somnus 30 it's been good for me at every temp from the upper 50s to the upper 20s.

I'd personally be hesitant to push the 30 too far into the low 20s but was fairly comfortable at 26 with baselayers, hiking pants, socks, LS tee and a down sweater inside the bag.

+1

I only have 1 bag (REI Sub Kilo 20) and have used it from -2 to 70.

maybe save the money on a new bag and just get a liner to supplement the 30F bag when needed? or as others have said, just use the 0F and vent it or use it unzipped like a quilt.

Liners do not work that well compared with an extra layer of clothing. I would disagree with that. They keep the bag cleaner on a long trip, hence, it will provide better insulation. But it takes a while to pay. A down sweater and pair of slightly oversized thick wool socks does better for warmth, IMHO. Bag liners are heavy for the 6-10 degrees of comfort I get and can be difficult to get out of at night. Bulk is generaly pretty good, but the 4-5oz(120-150grams) is usually better spent on a down vest or sweater.

I have two bags I use, like Daniel, a 0F and a 32F. Generaly, down has somewhat better temperature ranging than synthetics. I use the 0F for below 20F and have never needed to flap the bag. I skip the extra socks, pants and sweater. For warmer temps, most bags will, also, provide a vent at the bottom. And, I don't have to cover my feet and shoulders. So it is possible to defeat an overheat.

One of the older style military bags also provides a zip in liner. As I remember this was good to about 0F to 45F depending on the configuration. I can use either alone, or together. But it weighs about 4.5lbs total. My 0F bag is about 2#10.

Anyway, get the tent. With a bit of work on your kit, a 10-20F bag is not really necessary.