base + MB inner + rain jacket = ? (min temp)

Craig,

OK Dude this is short and sweet. It donna make any diff about BMR because we is all brow and besides the insulation amount automatically varies with different size jackets. It donna make any diff if you just remember that MET is different than METH. In utter words rather than saying I was chillin at about -10 let tell um what you was actually doing when you was chillin.

Ok Richard if I understand you, I should have added to my original post-
Original Post >Last October I hiked in a light weight long sleeve merino wool 1/4 zip t-shirt and a Montane Litespeed windshirt, regular hiking pants. After arriving to our campsite, in the dark the temp was 24*. I put on my Montbell inner under my windshirt and a OR fleece windstop cap, and fleece gloves. I was warm and comfortable with the above on, though I was only standing around and cooking for about 1 1/2 hours before going to bed.<
This should have been added…
I ate a hot meal, set up my tarp, Collected wood, build a small fire, and then checked on my scouts to see if there shelters were ok, sat around the fire and talked for awhile, then went to bed.

Would this have given better information?

Tad,

Yup… For example when you were collecting squaw wood for your fire you would have generated 3.5 times the amount of heat as a star gazer. Someone cooking dinner over an Esbit would generate .5x more heat than the star gazer. If you generate 3.5 times the heat, you need 3.5 times less insulation to stay warm at the same temp.

Most of the historical forum posts just say something along the lines of, "I was toasty in my 7.36 oz XYZ ensemble at some temp while inactive after a day of UL backpacking". Your revised post is much more valuable to others who want to learn from your experience without interjecting any potentially confusing technical terms.

Richard,

As always, you're full of great info–thanks! I would like to say that I think that your comment

"There seems to be a large number of the BPL forum participants who believe we are each so unique we each need different insulation amounts for the same MET level."

is a bit… skewed, for lack of a better word. I think it's a bit silly to say that we all need, or at the very least perceive the need, of different degrees of warmth. To greatly oversimplify calculations, if we consider your statement that individual BMR varies ~20%, and if we rounded up to 100*F ideal temp–individual needs would vary by about 20*F difference. To me, that could be a significant difference in insulation choice. Again, I realize I grossly oversimplified, but I think the general idea is sound… Cheers-

Thanks for your thoughtful responses.

To summarise, it seems there are some folks who can use the base/inner jacket/shell combo down to freezing, or below (!). Meanwhile others only feel comfortable down to 40-45F. Richard is suggesting that much of the difference is probably accounted for in the activity levels of the campers. Those who are more active in camp will require much less insulation.

There are so many factors which can affect how warm you feel that I guess you can't really know until you get out there and test it yourself. In the past I've usually needed 4 or 5 layers to get down to near freezing (35F)… but my mid-layers have been a heavy fleece jacket plus a couple of extra baselayer long-sleeves.

It's the mid-layer that I am finding to be a challenge. A montbell inner jacket on it's own doesn't seem much. If I want more warmth I then have to carry an extra layer, so I might as well carry a light alpine down jacket as a single layer. Sigh. I strongly suspect that, like Ben suggested, I will end up with two jackets — a UL inner jacket, and a light alpine down — and choose the one most appropriate for the conditions. Can't afford 2 jackets right now though!

I'd have to agree with Jamie's comment that conditions are usually coldest (or seem coldest) early in the morning before the sun hits camp. I've been bitterly cold in the French alps at 10am in summer, waiting for the sun to creep over a mountaintop and on to my side of the valley.

But it seems not many of you carry a montbell alpine light jacket (or equivalent) for 3 season trips, and instead just go with an UL inner jacket (or equivalent). Having just those 3 layers with the UL jacket as a mid-layer is a bit of a leap of faith for me, because it has been insufficient on past trips where my mid-layer has been a heavy fleece.

I use a cheap-o "champion" (target store) brand baselayer, looks like a road bike shirt I guess.. nylon/spandex blend. over that, a Down inner VEST and over that a 4oz windshirt. Like you say, when using a watchcap and light fleece gloves I am fine to 40. I would add a layer below 40 but pro'lly not necessary until 35°
Im sure a rain shell (being less breathable) like a marmot precip could take me down to 35 with ease. and, im skinny.