I already own a Western Mountaineering HighLite sleeping bag and love it for 3 season use down to freezing. However, I have some longer trips planned this winter and was hoping to supplement my current Western Mountaineering bag with a top bag or quilt to take me down to zero degrees fahrenheit. I know it's a bit more complicated than just adding or subtracting ratings and was hoping someone in the know or with experience might be able to make some recommendations. Thanks.

I would compare loft if I were you. I'm not sure how many inches a properly rated 0F bag has, or how many yours has, but thats probably a good starting point, and you try to make up the difference with a quilt. You might even be able to go a bit under because of the layers of fabric and dead air space between the two.

You might also want to consider synthetic because the dew point will likely lie somewhere within the outer layer. Your sweat vapor will condense inside this layer, best if it isn't down.

I'd also go for a synthetic quilt, for the reasons named above. Your options include the BPL UL 240, MLD Spirit, some enLIGHTened equipment quilts, Kick Ass quilts and if MYOG is your thing, the RayWay quilt.

Jorgen Johansson from Fjaderlatt has used two quilts - one down, one synthetic on top - to -18 C on his last winter trip to Sarek NP in Sweden. You might want to check his site for the article!

Edited by skullmonkey on 11/16/2010 02:13:23 MST.