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.
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.|
At this point the hammock body is inside a large silnylon 'taco' with the foot end of the taco sagging toward the ground.
1. Push the Insulator’s center pull to the side & get in normally.
2. Then pull the foot drawstring until you see or feel the airbag touch your back. (If you can't see or feel it then just put a slight amount of tension on the drawstring.) Tie or clip the drawstring to the ridgeline.
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.
The insulator has two basic components, shell and insulation. The questions are grouped into these sections. Comments about performance are at the end.
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.
I gather it's 9 feet long, but is it a rectangle? If so, how wide?
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)
Any thoughts on using tyvex.
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.
What's the material and what does the whole hammock system end up weighing?
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).
From: Gregg Spoering <gspoerin@s...>
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!
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.
--- In firstname.lastname@example.org, "Ed Speer" <info@s...> wrote:> I've used dry leaves in sealed trash bags to under-pin my sister's mobil
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.
ResponseI think you could put most of the stuff from inside your pack into the shell. That would keep it out of the weather and it could trap some air for insulation. If you were going to put velcro around the perimeter, you could probably cut a piece of silnylon to fit the bottom with the sidepulls in use (on the hennessey hammock). That would reduce the weight carrying capacity as far as filling the bottom with stuff from the pack, but you would get to use the sidepulls again.
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.
sitting on a leather couch: back 90-92
lying in bed: back 90
in HH with air bag insulation: ambient temp 32, back temp 78
(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.)
in HH with improved air bag insulation: ambient temp 30, back temp 88
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.
Newspaper!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). I currently am using one large bag (about 50 gal size). I laid them out with about a 4" overlap in the middle and slid them into the bag. Trapped a little air, tied off the bag, and slid the contraption into the shell. Voila! My plastic bag & 6 sheets of newspaper weighs in at 6oz. I thought the airbag by itself worked well.... this is magic.