This device consists of about 3 yards of silnylon with a drawstring stitched along each of the 9' sides. The drawstrings should extend about 2' on each side so that they may be tied to the hammock’s support rope.

Setup

Entry

Results

It helps a lot and doesn't weigh much. The silnylon around the body will help stormproof the bottom. I didn't miss the side pulls much. The hammock feels a little collapsed, but I didn't feel this was a problem. With this configuration, I think the head end is more storm-resistant than the foot end, so I'd pitch it about 45 degrees head into the wind.

Questions & Answers

The insulator has two basic components, shell and insulation. The questions are grouped into these sections. Comments about performance are at the end.

Shell

The purpose of the shell is to shed water, block wind and hold insulation against the bottom of the hammock. It seems to me that 30D sil-nylon is ideal; however, some have suggested just using other stuff. Here are some questions that have been asked about shell materials.

Yes, it is just a rectangle. I used the material just as it came off the bolt of fabric. (usually 58 or 60 inches wide)

I think the characteristics you want for the shell are light weight, windproof and waterproof. Tyvek meets those requirements. In fact, since it comes in wider sizes, you could fashion it so that it covers as much of the hammock's netting as you wanted.

The material in the pictures is a nylon fabric that was in the bargain bin at Walmart. For the 'final' product, I'd recommend 30 d sil-nylon. With the drawstrings, that would weigh about 9 oz. The plastic bag would weigh in about 4 oz. or less depending on thickness. you would also have to bring some tape to patch holes. I'd estimate about 14oz for the whole thing (shell, plastic bags & tape).

Couldn't a silnylon poncho (long pack cover style) be adapted for this for dual use?

Assuming it wasn’t raining, this would be an ideal use for it. Some short cords tied to the corners would serve as the ridgeline drawstrings. A longer cord tied to the middle of the foot end would be the draw cord. Good idea!

Insulation

Trapped air is a good insulator, and plastic trash bags are a good, cheap way to trap some. The plastic bag would weigh in at about 2 oz. or less depending on thickness. You would also have to bring some tape to patch holes. There are many good ideas about alternative insulators.

The air bags work surprisingly well, are very light, and pack small. I tried no insulation (just the shell), synthetic insulation (a sleeping bag), down (a sleeping bag) and the air bags. The sleeping bags worked well, but are too bulky and heavy to carry. So, other things are warmer, but the airbags work well by themselves.

Without some containment, the leaves would tend to slide out of the shell. Leaves in a plastic bag would be fine. If using leaves you wouldn't have to worry so much about punctures in the bag, since the leaves would trap air around themselves.

>>> I wonder if instead of the "air bladder" in your design, you could simply throw shoes, clothing, other essentials through the entry slit, into the 'taco' and elliminate my thermorest? Have you tried just stuffing 'stuff' into the taco?

yes. I tried various stuffings: none, poly insulsation (a cheap sleeping bag), down (an army feather bag), and the ultimate trapped air gizmo the plastic trash bag. The 'taco' by itself helped insulate some, and really is a good place to throw stuff you didn't want to put on the ground. The miscellaneous stuff would act as a spacer between the hammock bottom and the taco shell, assuring a volume of semi-trapped air was held.

I'm wondering if the plastic bag might be eliminated by using a spacer system of stuff already in the pack? We'd discussed throwing boots, clothing, etc. but I wonder if an even spacing of maybe 1" uniformly under the entire taco might allow the dead air space to come up a bit in temp. I find my HH is warmest when the mylar space blanket is luffing out a little. The seal is the problem if it's windy.

On a hammock I built, I rimmed the thing in velcro patches every foot. I can attach bug netting, storage bags, guy lines, whatever, all the way around the thing. It's made from uncoated ripstop and very light. Wondering if your taco might be velcroable around the perimeter of the hammock to form a good seal and allow uniform spacing? Gathered and tied at the ends, of course.

Regarding (>>> I wonder if an even spacing of maybe 1" uniformly under the entire taco might allow the dead air space to come up a bit in temp. I find my HH is warmest when the mylar space blanket is luffing out a little. The seal is the problem if it's windy. <<< ) This is the main advantage of 'bagged air'. It creates a rather uniform blanket of trapped air that is not subject to wind currents.

The shell encapsulates the body of the hammock. If you put a slit in each side of the taco, the pull outs could be used. If done, some gasketing as suggested by Dryer above would (probably) be beneficial.

Multiple airbags help reduce the probability of failure of a single bag, but would increase weight and take longer to set up (takes longer to inflate lots of bags). A single bag can be filled, tied and installed in about 30 seconds.

Rick had tried the insulator at below freezing temps and reported that his back was too cold. He guessed the temp was 50-60 degrees on his back. In the interest of science, I borrowed my wife’s indoor/outdoor thermometer and taped the 'outdoor' sensor to the middle of my back. I tied the thermometer body ('indoor'sensor) to my belt and spent several hours measuring temps (all farenheit). Upperbody clothing was a cotton tee shirt and a UNC sweatshirt (go heels). ower body clothing was 100wt fleece and dockers cotton pants. Socks were smartwool. All testing was done without additional insulation. I just had the t-shirt/sweatshirt lying directly on the target surface.

(I would like to corroborate Rick's impression here. Sustained contact with 78*F feels too cold. It can be tolerated, but isn't comfortable.)

OK, with the improved airbag, we are in the ballpark with lying in bed in a heated house! Subjectively, your back feels 'warm' at 88 degrees, and the hammock was quite comfortable in this configuration.

Improved air bag

Space Blanket!

Johnny_Swank (@Lightweight Backpacking) suggested using a space blanket instead of newspaper. A single well wrinkled space blanket can be loosely rolled about 5 layers thick to do the same thing the newspaper does. It is light and doesn’t absorb water. This is what I will be using from now on.

Performance

The Insulator shell has been tested under various conditions, and some of the test results are listed below. Generally, the shell by itself is sufficient down into the 60's. Below that some additional insulating material must be positioned between the shell and the hammock bottom.

13*F and breezy

I dressed in fleece (100wt top, bottom, & socks), inside a FF rock wren bag. Insulation was 2 partially filled trash bags. Inside the hammock after temps stabilized, the temp was 33*F on the surface of the sleeping bag, so there was about a 20*F warmup above ambient. My back was not cold, but there was a slight coolness that I didn't care for. Maybe a survival blanket thrown on top of the air bags would help. Also, I carry a 30x40x1/4" foam pad in case I sleep in a shelter. I'd use that inside the hammock, which would certainly take care of the problem.

40*, calm

I dressed in fleece (100wt top, bottom & socks). Insulation was 1 partially filled trash bag (a big one) with a mylar survival blanket thrown on top (between the air bag & the hammock bottom). The hammock was comfortable with no additional insulation (no sleeping bag).

28*F calm (test by Rick -- geoflyfisher)

I had the privledge of spending about 4 hours hanging in my HH last night out in the front yard. During that time it snowed about 2 inches. Temp about 28-30F, very little wind. I read about half of Ed Speer's new book and did a little napping. Trying to explain to my kids and wife that I had not gone around the bend was the hardest part of it!

I had added a layer of air insulation to the bottom of the hammock by constructing a Garlington Insulator as previously posted. For details you may want to check out my site at http://www.flyfisher-kayaks.com/ultralite/ultraindex.htm

The hammock was comfortable... no aches, no pains, able to stretch out flat across the center line, able to sleep on my side... all the stuff people claim.

I was wearing the same outfit I had hiked in before supper. Nylon shorts, nylon (home-made, uncoated) wind pants, cool max socks. Cool max undershirt, fleece top, wind jacket. Homemade fleece baklava.

I was using a home-made quilt of two layers of polarguard which loft only about an inch, but it is big enough that there was a lot more real loft in the hammock than the thickness would indicate.

The Garlington insulator with a single partly inflated plastic garbage bag was warm enough for only about 2 hours at this temperature. The bottom of the hammock was much warmer than the outside, but much cooler than I was comfortable with for an overnight sleep... Maybe something like 50-60 degrees??

I added a Wal-Mart egg shell closed cell pad and was in seventh heaven. Nice and warm... but man that thing stick to every surface and refuses to move around. I have not been able to even unroll it in my ruck sack because it sticks to everything... so I think I am going back to Wal Mart to buy the cheap $6 mat and try that.

With the mat I was comfortable until I decided to go inside and snuggle for the night. I think I would have been comfortable all night.... Now tonight, it is to go to 10 degrees.... I wonder...

Rick

5*F, breezy Test done by Rick – geoflyfisher

Synopsis: It works! I was warm.

Weather in Dayton: 2 inches of fresh snow. 11 degrees F at 1030 PM when I went to bed... 10-15 mph winds... ("wind chill" of -2) 0530 when I got up, 5 degrees, "wind chill" of -10. It did not rain.

Hammock set up: HH (ultralite asm stock) with Garlington insulator "taco shell" and 3 partly inflated black garbage bags. Jardine tarp (9 x 10 feet plus peaks) instead of HH tarp.

Inside: Walmart egg crate closed cell pad, Target 3/8" closed cell pad. Both full length. Home-made quilt a la Jardine, 1-1.5 inches of Polar guard 3D. (But the quilt bunches up on top, effectively increasing the thickness.) Sleeping directly on the pads, with the quilt coming down to the pad but not under me.

Clothing: Nylon hiking shorts, Coolmax tee, Medium wt fleece top, light weight fleece pants. Light weight (home-made) fleece baclava. Coolmax socks and Snakeskinz socks.

Note: I would normally have all this with me with the exception of the second (egg crate) pad... I also had in reserve my nylon wind pants and top, FroggTogs rain suit and polypro long underwear! Did not need it!

This was my first night in the hammock. It was a little too cool on my feet to stretch out across the midline for very long...(My feet compressed the quilt against the outside wall where it is not protected by either the insulator or the pad) so I spent most of the time in fetal position on one side or the other. Next time I will cut some of the corners of the pad off so I can get it further up under my head. I had no pillow, and was occasionally mindful that my hair is not long enough to insulate my head inside the light baclava. (Active duty AF sort of thing.)

In the fetal position, I occasionally had some ache of the upper knee and found relief by crossing my feet and getting the knee into a more normal anatomic position.

Middle of the night I got up for the necessaries and just wore my sealskinz out on the snow without putting my shoes on... Felt warm, but some ice stuck to the outside of the sealskinz and I had to scrape it off with my thumbs... next time I will slip my shoes on.

This morning, there was a tiny bit of moisture which had collected on the hammock fabric about where my face was. My breath had condensed on the fabric. Inside the GI at the same spot, there was a little frozen condensation. The quilt had no condensation on it that I could find.

So that's it... Only one cheat (second pad) and this is considerably colder than I would normally think of hammock camping. For the spring when it might occasionally get down to 15 as a surprise, I believe I would not only survive, I could be pretty comfortable. I did not need to resort to putting the hammock down on the ground. The GI seemed to really do its job to the extent that the pad never seemed cold at all.

V/R

	A pull cord (about 6' long) is attached to the middle of the foot end, which allows the shell to be closed after entry. In the picture, the cord is simply tied to the middle of the material. Note: Rick (geoflyfisher) came up with an improvement by making a draw string along the entire foot end of the insulator shell which ‘escapes’ from the fabric in the middle of the bottom. The pull cord is attached to this foot-end drawcord. This enhancement draws the excess material more tightly against the hammock bottom sealing it more effectively against drafts.
	A loop of light cord is attached to the hammock’s ridgeline, inside and as far toward the foot end as possible. The drawstring from the foot end of the insulator shell passes through this loop.
	An air bag, air mattress, plastic/mylar/poly bag or other lightweight airtight contraption is used as the actual insulation material. These are just plastic trash bags that have been slightly filled with air and tied off with a twist-tie or rubber band. Enhancement: Get about 6 double-wide sheets of newspaper. Crumble each one into a tight ball to put a large number of wrinkles into each sheet. Unfold them, stack them lightly, and arrange them to fit into your plastic bag(s). Alternatively, and probably better, wrinkle up a ‘survival’ blanket and loosely fold/roll it into a 20” wide by 40” long blanket. You should get about 5 layers. Put that into your bag, then add air and tie off.
	These bags are placed between the insulator shell and the body of the hammock.

	1. Disconnect the hammock's side pullouts. They will not be used.
	2. Tie the Insulator's drawstrings to the hammock's support ropes at the head end and at the foot end. 3. Gather the excess material at the head end of the Insulator; and tie it around the support rope at the point where the hammock body starts.
	4. Slide the silnylon towards the foot end (along the drawstring) until it lies smooth.
	5. Run the middle drawstring at the foot end through the hammock's entry split and through the loop (on the ridgeline, inside foot end of the hammock).
	6. Catch a little air in your air bag and tie it off. (I used a leaf bag and a twist-tie.) Throw the airbag between the hammock body and the insulator support. Position the airbag(s) as desired.

The Garlington Insulator for the Hennessey Hammock

(1/16/2003)