I'm looking to make a light jacket for night hiking in temps down to 20F or so.

For insulation down is out because of sweat, so APEX or Primaloft (others?) are in.
What weight insulation should I consider? 5oz? 2.5oz?

What should I be concerned about for shell/liner fabrics and which are best suited?

I'd like this to stay under 12oz.

I hike in my down sweater and down coat often at those temps (really, anything from 40-0F is pretty common). If you're worried about moisture, a breathable shell would take care of it.

Most folks don't use more than a baselayer and windshell of some kind down to 20. Ideally you'd have just enough wind protection, thus maximizing breathability.

Insulation for standing around in those temps is another question.

If you're looking for extra insulation while moving, a fleece vest is a super easy project and would be better than syn insulation. You can get Polartec/Malden Mills Hi-Loft fleece (same stuff in patagonia R3) from Rose City Textiles.

https://www.fabricline.com/searchResults.php?a=1&keywordSearch=hi%20loft%20shaggy

Aaron Sorensen had suggested to me that down would not stay lofted on an overnight hike.

As it is, I'm nearing completion of a down jacket (should be ~12 oz) with plenty of loft. The shell and liner are both M90. I suppose I should see how that dampens under some long mileage.

I want to get started on a synthetic version to have options. The fabrics have me concerned for durability and moisture function.

I've hiked in base+fleece and that got cold & wet real fast in fog. Not very thick though.

I also just picked up a golite shell (from Aaron in fact) so I'll try that too. It got a little clammy on the arms on a short hike without sleeves on the base layer. I'm considering dropping the underarmour t-shirt for a full sleeve base. Better for the sun anyway.

All of this is in prep for a JMT fasthike. I'm set to do a test run at the end of June (Happy Isles to Florence fast, then slow to Whitney w/family) Then the whole thing in September, prolly NB, aiming <5 days.

It is hard to tell you which weight to use. I would say the 2.5 ounce if walking but maybe you are chilly and would want more.

The M90 fabric is good. It is much easier to work with than the M50. The M50 is thinner and you will save weight, but I decided the weight saved for a vest or something of a similar size was not worth the cussing. There are some threads with tips about sewing really thin material like M50, if you decide to use it.

A vest might be a thing to think about. A vest under a shell is warm. If it is chilly enough to want a vest, I would want something on my arms under that shell and would wear some kind of long sleeve shirt rather than the t-shirt.

I don't hike/work in my vest, but I do wear it under a wind jacket while walking around and I like it. The wind jacket has a hood and the head has a wool cap. Fine for me strolling in the low 30's. Maybe fine hiking in colder temps.

A vest is easier to make than a jacket. If you have sewn much before, that won't matter. If this is a fairly new hobby, vests are a good starting point.

There are threads with ideas about accounting for the extra length when quilting and etc.

PS - If I remember correctly, the M90 is more breathable than the M50... I don't have either with me now, but I think I could draw more air through the M90. This was using the sea lamprey test. Someone will correct me if I am wrong.

Edited by Tan68 on 02/10/2013 12:55:54 MST.

I always find that if I hike in synthetic or down insulation I am far too clammy after about 5 minutes unless I am going downhill or barely moving (maybe if with a slow group) I find base layers and lightweight fleece mid layers to be far more comfortable.

But my wife is bale to hike in a 100gm2 primaloft jacket, go figure :-)

> night hiking in temps down to 20F or so.
If there is enough light that you can move at a fairly normal speed, then daytime clothing is close.

I would have a light thermal layer (light Capilene?) under a windshirt for those condition without wind. I would have an uninsulated light EPIC jacket on top for wind. For 'bad' weather I would have more of course: maybe a 200 weight fleece top instead of the windshirt.

Travel cool at all times. Down and synth is XS.

Cheers

Thanks for the pointers. It's so different squeezing out the ounces. Used to be I had multiple ways to stay warm. Now I think I go with long-sleeve base (6.3) + WPB shell (9.3) for wind/rain. Add down jacket (12) for campsites. 27.6 oz total. Still a very sizable chunk of my 9.1 Lb base weight.

"Most folks don't use more than a baselayer and windshell of some kind down to 20. Ideally you'd have just enough wind protection, thus maximizing breathability.

Insulation for standing around in those temps is another question."

+1