My thoughts on the vented overcover.

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My thoughts on the vented overcover.

#1

Post by Scuba » Thu Feb 18, 2016 1:22 pm

I like it but I think it suffers from a design flaw.

I recently used mine when temps got down into the low 20s and woke up to find the inside of the overcover completely covered in frost from condensation. The problem, I think, is that the warm moist air I am exhaling isnt escaping through the net venting. Like most of us, I sleep with the foot end slightly higher than the head end. The exhaled warm moist air is this traveling AWAY from the vented area and towards the middle of the hammock and then the foot area. I think the overcover would perform better if the vent was moved more towards the middle of the overcover and made into a maybe 12 inch wide by 24 inch long mesh window that sits atop the ridgeline. I will break out my mad MSPaint skills and try to show what I am talking about.


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Re: My thoughts on the vented overcover.

#2

Post by Scuba » Thu Feb 18, 2016 1:32 pm

Sparrow2.jpg
I used the picture of my most recent purchase, a DH Sparrow to show what i mean by the new placement. Have the vent sit 24 inches long and 12 inches wide, or 6 inches on either side of the ridgeline.
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Re: My thoughts on the vented overcover.

#3

Post by Scott » Thu Feb 18, 2016 3:46 pm

I have not used an over cover, but if you are using it to keep the warm air in to get a bump in temp, would the new placement defeat that purpose by letting the warm air out?
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Re: My thoughts on the vented overcover.

#4

Post by bobamos » Thu Feb 18, 2016 5:27 pm

This is an interesting subject. I have wondered just where the perfect opening could be placed (or openings). Openings will vent moisture but will also vent heat. Perhaps the answer might be in the materials used?
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Re: My thoughts on the vented overcover.

#5

Post by PapaSmurf » Fri Feb 19, 2016 10:13 pm

Hi Scuba,
Sorry to hear of your condensation problems with this one. It definitely sounds like more and better venting was needed under these conditions.

This is where the ThunderBird and DangerBird has an advantage. They have the ability to upzip the overcover more and provide a larger opening to vent moisture from inside the hammock.

Since the Sparrow's zippers start at each end, providing add'l venting at the ends is more difficult. The Sparrow does have the advantage of being able to open up one or both sides to encourage more airflow and combat condensation. In our original Sparrow video, I showed how it's possible to open up either side by attaching a small weight to the velcro zipper seal and flipping the overcover back. What I didn't show was the ability to partially open up the sides. We have been experimenting with hooking a short length of shock cord to the hole in the zipper seal and hooking it to the ridgeline. With the correct tension on the shock cord, you can unzip the cover slightly and open up an adjustable vent right near your face. We are also looking at the possibility of adding a small piece of grosgrain ribbon to the asym point of the overcover that will make this extra vent area more effective.

While it would be possible to adjust the size or change the positioning of the vent, I don't know that it would be the right choice for all users in all conditions. I think for that we have to look at being able to open the zippers to provide more venting when the situation calls for it. I'd be happy to send you down a couple shock cord & mitten hook thingies we have if you'd like to experiment with opening up the sides.
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Re: My thoughts on the vented overcover.

#6

Post by Scuba » Fri Feb 19, 2016 11:05 pm

No need to send me goodies, you already have spoiled me and ruined me from using anyone else's products. I honestly didn't think about cracking the side zippers on the sparrow. I never had the issue on my T-Birds because of the ability to unzip the ends like you described.

Good answer, Randy!


PS, expect another order soon of a Robic Sparrow.
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Re: My thoughts on the vented overcover.

#7

Post by Fastmatt » Wed Apr 20, 2016 1:17 am

How about increasing the size of the vent and using a lil extra Velcro and material to allow the user to customize the size of the vent while laying in the hammock as situation changes. You could leave a permanent opening and then use this to make it larger. Idk just an idea. It would add a very small amount of weight but very minimal as its not load bearing at all so both Velcro and material could be on the skimpy side

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Re: My thoughts on the vented overcover.

#8

Post by PapaSmurf » Wed Apr 20, 2016 7:58 pm

Fastmatt wrote:How about increasing the size of the vent and using a lil extra Velcro and material to allow the user to customize the size of the vent while laying in the hammock as situation changes.
This is pretty much how the ThunderBird works now. You can simply bring the zippers down and change the size of the opening at the head end.

We currently have a few other ideas in the works, but precious little time to work on them at this point.
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Re: My thoughts on the vented overcover.

#9

Post by BillyBob66 » Wed Apr 20, 2016 8:25 pm

When I set my all time personal best a couple of years back at 6F, I was using an HHSS including the Over cover, which has a maybe 6" diameter vent near my face. But because I had noticed that it I felt an increase in the apparent humidity occasionally when I would use the OC in not so cold conditions, and sense it would block some of the wind if I had any, I was expecting a ton of condensation at this near zero temps.

But 2 things were different this time:
1:for the 1st time, I was sleeping in vapor barrier shirt and pants/socks.
2: I rigged up a fleece frost bib that hung from the RL in front of my face.

I was pretty surprised the next morning. Though the frost bib was pretty soaked, everything inside and under the hammock was bone dry, no sign of moisture anywhere. I was really surprised.
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Re: My thoughts on the vented overcover.

#10

Post by G_Man » Sun Apr 24, 2016 8:34 pm

Interesting discussion, I'm learning a lot! I've stayed away from socks or an overcover because of the condensation issue. Venting location seems to be less important, as long as there's airflow. I'm surprised a frost bib helps as much as it did BillyBob.
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Re: My thoughts on the vented overcover.

#11

Post by TXyakr » Mon Apr 25, 2016 11:39 am

When sleeping outdoors there are a lot of variables to adjust for, generally speaking hammocks allow for more adjustments than a tent. I have not tried these vented over covers but I agree with Randy's assessment. When it is below freezing for most of the night there are very few bugs so a bug-net isn't required. Therefore just unzip the over-cover until you get enough ventilation to suit the conditions. Even an over-cover half way open should still trap some of your body's heat and block the wind better than just a tarp. The only over-cover (in addition to a tarp) I have used is a a military poncho hung over the hammock's ridgeline, it seems to help trap some heat and is multipurpose. I purchased a zip-on fabric over-cover (in addition to bugnet) with one of my hammocks but have never used it. I just don't like zippers if they aren't necessary. I'm not concerned about critters joining me while I sleep when it is close to freezing. Can happen, but unlikely. In warmer weather I have woken up with various things crawling on me, I didn't panic just gently brushed them off, but that may just be me. I grew up with a lot of critters, have been stung and bitten by many but none killed me, not even the really bad ones that hurt for days. ;-)

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Re: My thoughts on the vented overcover.

#12

Post by BillyBob66 » Mon Apr 25, 2016 12:35 pm

G_Man wrote:Interesting discussion, I'm learning a lot! I've stayed away from socks or an overcover because of the condensation issue. Venting location seems to be less important, as long as there's airflow. I'm surprised a frost bib helps as much as it did BillyBob.
Me too, surprised at the amount it helped, apparently. But condensation is often a mystery that happens for some combination of reasons that is hard for me to calculate how they are all going to come together for a soaking wet result. For one example of many, one time while camped beside a river in the uber humid rain forest of western Olympic National Park, using my HHSS(same set up as in above post about the bib at 6F except no over cover just netting), first night of the trip it was only supposed to be high40s to low 50sF. We set up camp late in the dark, so I did not bother placing my space blanket(SB)/vapor barrier under the hammock on top of the pad. (I was pretty new to this stuff then, and did not quite realize how important that SB was to this system. When I got up the next morning- though I slept very warm and comfy- I discovered to my dismay that the foot of my synthetic sleeping bag and the foot end of the HHSS open cell foam under pad were pretty soaked. Luckily they were nice and dry by the end of the day, and I used my space blanket on all othrr nights and was nice and dry.

So OK, I well understand now about the importance of the SB/VB for minimizing condensation with this system(HHSS). And I paid the price that night for ignoring this principle. But, why was virtually all of the condensation at the foot end of the bag and under pad? I have heard from one or two others over the years who had a similar foot end condensation experience. What part of condensation magic accounts for that? Is it because the feet put out lots of vapor? But surely not more than breathing. Maybe even then I hung with the foot end slightly higher, and all of the vapor I breathed out rose towards the foot end before condensing? But, if it was breath vapor condensing, why did just adding a space blanket keep it from condensing on the sleeping bag and space blanket? It is a mystery to me. I have also heard and known of guys using light down bags in tents and the first thing to get wet and loose loft is the foot end of their down bags, even though there was no evidence of rain getting into the tent, nor of significant condensation elsewhere.

I am not surprised my frost bib had a lot of condensation on it, but I was surprised there was none at all elsewhere. Now another 1st was vapor barrier clothing torso to toes. So that would stop any vapor from the body from migrating to the outside of(or outer layers of) the top quilt and condensing inside the over cover(or inside the TQ). But, if that was a factor, I guess I am surprised it helped much since it seems like that would be a small amount of vapor compared to my exhalation. But bottom line and for whatever combo of reasons, dry as a bone(and very warm) inside an under and over cover at 6F, except for the frost bib. Also, don't forget there was about a 6" diameter vent hole near the left side of my face/lt. shoulder. The bib hung immediately above my upper chest.

I can't help but wonder how I would have done without the bib and VB clothing, depending only on the vent hole. But, I don't think I have heard of anyone else being quite so dry inside a sock/over cover/ under cover at those kinds of temps. You can see I was pretty well covered up by this picture from another rainy day:
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