PDA

View Full Version : Tarp users: Does it ever rain under your tarp?



TwoForty
11-12-2005, 21:59
Last weekend I had my siltarp pitched a-frame style, but before I could even crawl in, it was covered in condensation/dew. It was a very wet area. It was very windy and it rained lightly in the morning.

I woke up around midnight and my bag and ground sheet had a nice layer of wetness. When I woke up from the rain in the morning, I could actually feel it raining (lightly) inside!

I really doubt the rain was blown in and I had the sides pitched low to prevent splashback. It wasn't a heavy rain, so I don't think it went straight through the tarp. Could the wind have blown the condensation from the tarp onto me? Could the rain have also knocked condensation onto me?

I have used this tarp (campmor 8x10) and a lunch shelter in stronger rains and I stayed perfectly dry.

swede
11-12-2005, 22:21
I have had that experience as well. Rained crazy the first two days of our trip in the Smokies this past July. If moisture condenses on the underside, rain can certainly knock it onto you. The humidity won't allow much evaporation, so we just wiped the walls down occasionally.

TwoForty
11-12-2005, 23:02
I have had that experience as well. Rained crazy the first two days of our trip in the Smokies this past July. If moisture condenses on the underside, rain can certainly knock it onto you. The humidity won't allow much evaporation, so we just wiped the walls down occasionally.
Where in the smokies were you?
I'll be there again in the summer and I am not sure if I will use a tarp or a tent.

peter_pan
11-12-2005, 23:10
This sounds like the fog that is thick enough to cut scenaro. Yes? If so, this is fairly common in the mountains under the right temperature inversion and dew points... Couple of years ago on a March start for the southern 600 mile I carried a space blanket, folded in half lengthwise with the bottom and bottom 24 inches of the side tape with packing tap to form a foot box... I put this over my quilt to prevent wet out fron the dense fog and condensation forming then dropping from the underside of the tarp...when I got up for natures call I would then reverse the space blanket so as to reduce the trapped vapor from me to a minimum... each morning, or as soon thereafter as practical, I had to wipe down the space blanket.

Ground tarpers can use bivies to solve this problem .

The JRB Weather Shield Top which is waterproof, windproof and breathable was specifically designed to solve this problem, at 9 oz it is heavier than a 2 oz mylar space blanket... But the breathability feature makes it absolutely dry and a no brainer to use... currently on sale at 40 percent off....works in hammocks, shelters and on the ground...Note, as designer and maker I'm biased.

Pan

TwoForty
11-12-2005, 23:23
This sounds like the fog that is thick enough to cut scenaro. Yes?

Yeah. I forgot to mention that you couldn't see 5 ft becuase of the fog!
I suppose it could have also drifted in and condensated directly on me. This would explain the wetness arounf midnight.
I doubt that is what caused the morning "rain" though. I guess the rain knocked the water off of the underside of the tarp onto me.

swede
11-13-2005, 00:35
Where in the smokies were you?
I'll be there again in the summer and I am not sure if I will use a tarp or a tent.
We were near Cherokee(Mile High Campground) camping after my wife spent a week at Teacher Academy at WCU. The ridge was in the 5000' range. We were using a single wall tent, plenty of clouds coming over that ridge with the rain.

TwoForty
11-13-2005, 01:11
We were near Cherokee(Mile High Campground) camping after my wife spent a week at Teacher Academy at WCU. The ridge was in the 5000' range. We were using a single wall tent, plenty of clouds coming over that ridge with the rain.
Ah.
I'll be sure to stick to shelters at high elevation and use the tarp in the lower, less exposed areas.

general
11-21-2005, 20:23
oddly enough, if you raise the sides or side of a tarp when the humidity is high you can create a little more air movement under your tarp therefore decreasing the ammount of condensation on the underside. that being said, when the humidity is 100% on the outside it's 100% on the inside too, not a whole lot you can do.

SGT Rock
11-21-2005, 20:26
Ah.
I'll be sure to stick to shelters at high elevation and use the tarp in the lower, less exposed areas.
Since we are talking about water vapor, you would be just as exposed in a shelter wouldn't you.

smokymtnsteve
11-21-2005, 20:30
Since we are talking about water vapor, you would be just as exposed in a shelter wouldn't you.

back in 1999 I was living in Cherokee NC in My Airstream,,,I rained heavily for about 2 weeks ...super high humidity,,,things were even damp inside the Airstream from the humidity so YES the high humidity would make the inside of a shelter damp also