Did my first field test last night with the full (well, so far) version of my modular under-insulation system. It needs a bit of tweaking, I think. Back to the drawing board for some of it, and a simple addition to another.

Location: Super Secret Test Site #1 (my front yard)

Met Conditions: Temperatures ranging from 48* F to 42* F, winds ranging from 5 to 10 MPH (windchill from 44* to 36*), RH ranging from 93% to 100%, occasional light precipitation.

Clothing: Patagonia Capilene 3 longsleeve top; mil surplus polypropolene "Drawers, Cold Weather" bottoms; wool watch cap; Darn Tough hiker socks as liners; vapor barrier bags (Publix vegetable bags) over liners; thick, loose Wigwam wool socks as primary insulation socks.

Top Insulation: Mil surplus poncho liner used as top quilt.

Tarp: Standard tiny asym diamond.

Underquilt: 20* DIY 7-chamber, differentially-cut down quilt. M50 shell, 4" nanoseeum baffles (before seam allowance; ~3.5" after sewing), 14 oz of 850 fp down.

Undercover: 30d sil poncho, vented at head hole and ends.

Test Subject Information: I had a fairly easy night at work last night; I was sober, well-fed (an individual size pizza at ~2 hours before bed), and well-hydrated.


Results:

I slept very well and warm for the evening. I woke once due to my neighbors coming home at ~3 AM, but aside from that slept straight through from ~1 AM to ~7:30 AM. I woke and checked my underquilt by sticking my hand between it and the undercover. It was very damp from condensation, and I got up to make coffee before making any other observations.

An hour later, I went back outside to check on the quilt. I removed the undercover from the hammock, and discovered that the edges of the quilt towards the top were less damp than the bottom. However, there did not seem to be any loss of loft (I think this might've been eaten up by the ~20% overstuff I did on the quilt, along with M50's lack of water permeability). I wiped down with a dry bandanna, removing what I could, and skinned the hammock and insulation before taking everything down.

I'm going to set it up again tonight (the forecast is for ~39* F tonight with considerably less humidity) and see if there's any noticeable loss of loft or temperature rating.

As of right now, my first impression is to add suspension attachment points to the underquilt, rather than the hammock, to allow the UQP to hang lower (and therefore not actually in contact with the underquilt). We'll see if that's truly necessary, or if the total amount of condensation in/on the quilt is worth worrying about.

The other option is to drag along my space blanket and fit that between the underquilt and the hammock. But that would mean sleeping on a vapor barrier, and I am very leery of doing it. The few times I've tried that in the past, I've woken up damp and cold (though spot vapor barriers, like what I wore on my feet last night, have worked for me so far).