And it explains why I use a full sock when I can, both for a RR or a GE. It’s sort of like a suspended single wall tent. The interior surface of the sock can get frosty - depending upon how much venting I allow - but the quilts stay pretty dry. And what knocks off in the morning can be pretty easily brushed off the Quilt.
In order to see what few have seen, you must go where few have gone. And DO what few have done.
Originally Posted by blgoode
I think Y'all are right. If that article is correct, bug netting(in addition to the tarp or any tree cover or clouds) would act as over head cover, and reduce the tendency of the inside surface of both the hammock and quilt shells to drop a couple of degrees below air temp due to radiant cooling, and thus drop below the dew point. It would also help keep the air inside the net a bit warmer, possibly reducing condensation.
But, this must be weighed against the experience of quite a few people inside socks, who complain of much increased condensation. All of this has me thinking of my very dry +6F night inside the "sock" of the HHSS with over cover. I can't remember with absolute certainty, but in addition to the 6" diameter vent hole near my face, and the frost bib, and the VB clothing, it seems most likely to me that I had the net closed, with the over cover over the net. I wish could remember for sure. Because, if I did, this would have formed a sort of double layer, with at least a tiny layer of air between the net and over cover. Just 1 more layer to prevent the surfaces inside the "sock" from dropping below air temp due to radiant heat loss. And in fact, the over cover would have reduced the tendency of the net from doing any of that. All of which may have contributed to my dry night.But, I can't remember for sure.
I definitely keep a section of the zipper path (both side of the sock if it has them) open for some ventilation.
In order to see what few have seen, you must go where few have gone. And DO what few have done.
I can't imagine staying dry while breathing inside a nylon coffin all night. But I definitely need to try if it's working for some.
Bug net is easiest to try. Makes since what he said about temps causing it vs your moisture. Heat rises so you have more eat at lower portion of you since footbox is higher.
Also an example of the climate causing condensation and not you is when I take guns inside or outside when it is drastic temp changes they become very wet and need wiped down. The gun isn’t producing moisture but the climate conditions and differences are causing the condensation.
Over the weekend, I was fine one night. Wet the next.
The first night was 30 and very damp after raining/mist most of the day, but I slept dry. I think it was the 5-10mph wind all night.
The second night was clear and dry but DEAD calm. 30° again. If I was backpacking and had to stuff that up, I would have been screwed unless it was a sunny evening to dry things out.
Just out of curiosity, did you pitch your tarp the second night or no? I was at a local hang a couple years back, and most folks decided to camp w/o their tarp, since it was clear w/ no chance of rain. I chose to still pitch my tarp though. In the morning, everyone who slept w/o the tarp was soaked from condensation, not from rain. I stayed perfectly dry because the moisture condensed on my tarp, and not on me.
Yes I did my usual porch mode. My dad slept in an oldschool Gander Mountain backpacking tent with rain fly (new in package from the 90s!). He said it was also really damp.
The example cited ignores the two conditions that matters, which is the humidity, specifically the relative humidity and the dewpoint.
Relative humidity is the amount of water vapor that the air at a specific temperature is able to hold.
What is dew point? (Calculator.net)
Dew point is defined as the temperature at which a given volume of air at a certain atmospheric pressure is saturated with water vapor, causing condensation and the formation of dew. Dew is the condensed water that a person often sees on flowers and grass early in the morning. Dew point varies depending on the amount of water vapor present in the air, with more humid air resulting in a higher dew point than dry air. Furthermore, the higher the relative humidity, the closer the dew point to the current air temperature, with 100% relative humidity meaning that dew point is equivalent to the current temperature. In cases where dew point is below freezing (0°C or 32°F), the water vapor turns directly into frost rather than dew.
One point of reference is that temps below 32-degrees F mix with the ambient temp of your sleep environment to provide a swirling mix of (at your lowest temperature example - of which I chose to use deg-F) moisture laden air vapor and frost which travel to landing places in your immediate area (top quilt/face covering/etc.).
25-degrees (I will choose deg-F as my reference) So check the Psychrometric Chart: 10-15 grains of water per lb. of ambient air between the temps of 25-degreeF and 38-degrees F. See the chart below. One pound of air is a 2.3 foot cube.
NOTE: the 10-15 grains of water is equated to each and every exhale during sleep. (put an 8-hour video feed of your top quilt condensation).
http://www.truetex.com/psychrometric_chart.htm
25-degree
26-degree
27-degree
28-degree
29-degree
30-degree
31-degree
32-degree
33-degree
34-degree
35-degree
36-degree
37-degree
38-degree
Note that the dew points at these 14-temperatures represent the amount of water vapor that the air is able to hold, until the relative humidity at THAT temperature reaches 100%. Now, under this specific condition, for every molecule of water vapor exiting your skin and your lungs represents a molecule of water vapor which must float away - BUT the air is at 100% Relative Humidity at that specific temp and therefore a molecule of condensed water will form on whatever surface it encounters, along with the 100% water vapor saturation embedded in the ambient air as well.
The surface of the material that is available for capturing that molecule of air vapor is your top quilt surface that is exposed to the cold temperature. As your lungs exhale the vapor condenses against the cloth covering your mouth/nose, and forms a wet condensation. When this condensation reaches the saturation point of the cloth, the cloth can no longer absorb the vapor, and that vapor is now forced outward to be condensed against whatever surface is at the dew point temperature of the ambient air. This is why the open porch mode of the tarp assists in the stirring of breezes to move the vapor molecule to a surface.
That specific capture/contact area for water vapor and frost is your midsection, which is presumably lower than you head. Gravity seems to assist the mid-section accumulation. As others have said, that portion of your body is the engine, where the body stores its heat reserves, letting the extremities become colder.
The vapor molecule is heavier that the ambient air is able to support and so it settles against the surface of you top quilt not as a vapor molecule (that has already escaped your mouth/nose covering forced out by the exhalation of your breath), it now forms a molecule of water deposited against your top quilt.
Stabilize the air movement under the tarp, and the water vapor molecule is limited in the distance it travels. So this where you provide a landing zone for that 10-15 grains of water vapor which the dewpoint of the air can no longer hold (for every 2.3 cubic feet of air), and it is forced to deposit as a water molecule. Give it a landing zone, or it will find its own.
Increase the air movement under the tarp and you will assist the water vapor molecules to pass beyond the hammocks boundary layer of warmth.
Last edited by joe_guilbeau; 05-12-2021 at 23:11.
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