Poncho Liner Hammock Under-Quilt

[SGT Rock]

Here is a new little tip I have picked up while here in Baghdad. It is a way to make a field expedient under-quilt for the Hennessy Hammock using some simple material and easy to get items. As many of you may know, I have scoffed at the idea of an under-quilt for the Hennessy Hammock in the past. When I got the hammock, I decided to play with a quilt to see if it could be effective since I would get a lot of nights to play with different set ups. After using a quilt with the hammock, I am sold on the concept.

To make this quilt you will need:

1. About 1’ of 550 cord.
2. About 3 feet of elastic cord or elastic straps.
3. A poncho liner, preferably a Thinsulate liner
4. A sewing needle and some thread.
5. A pocketknife or scissors.
6. A two small stick about 1” long.
7. Optional: some fleece material.

Before I go on, I must say that even though it costs a little more, if you are looking for a poncho liner the extra loft and warmth of a Thinsulate poncho liner over a surplus liner is definitely worth the extra money. This project could be done with a surplus liner, but I can’t vouch for the warmth and performance my Thinsulate liner has given me. The Thinsulate liner weighs about the same 20 ounces as a surplus liner, but is about ¼” thick when lofted, and it compress and lofts again very well.

I figure this design would be something any hiker out there that finds they needing an under-quilt in a hurry and can get a poncho liner sent could produce on the trail.

[SGT Rock]

The first thing I do is cut an 18” long slit in the liner to form a head hole. As an option you can finish the neck with some fleece material. In this case I sacrificed an old pair of Army polypro pants. When used under a jacket or poncho, these liners can give you a lot of extra warmth. In this case, the liner also serves as a cold weather-clothing item. It would be the same as having a 10-ounce pad under you and a 10-ounce fleece jacket for pack weight except the liner is warmer than 10 ounces of pad when used with the hammock, and it is a lot warm if used right under a poncho or rain jacket than a 10 ounce fleece top would be.

Then I fold the liner into thirds along the longest part. The Total length is about 58”. I am 68” tall, so this leaves about 10” under my feet that aren’t covered, but that hasn’t been an issue yet. The main thing is it gives ¾” insulation under my head, shoulders, back, butt, and upper legs. The width after folding it into thirds is about 28”.

[SGT Rock]

To make the corners stay in place, I poked small holes in the edge trim of the liner using a knife that I could pass the strings of the liner to tie it and hold the shape. Next I took a 2” long piece of 550 cord and removed the guts to make a flat cord loop which I sewed to the center of the side that does not have a tie on it, swing all the way through the material. In the future I would probably put some material on the other side to make a tougher anchor.

Then I took the elastic and made six 6” long elastic ties which I simply tied into the base of the original strings at their center point at the four corners. At the sides I tied it the same way to the side that has the original string, and on the 550-cord loop I created it was fastened there.

[SGT Rock]

There will be a little sewing on the hammock, but nothing that will tear it up. I learned a couple of lessons the hard way on what doesn’t work. Take some more 550-cord and remove the guts. Make five 2” long loops then sew them to the edge of the hammock where the net and the hammock body meet. The best method I found for this was to place the loops with one end on top, and the other end on bottom there should be four of these, distances are given from the center pull out:

[SGT Rock]

To attach the quilt, start at the head and tie off the elastic using a bowknot, just like tying your shoes. Don’t tie it tight; there should be some slack. Then do the exact same thing at the foot end to both sides. Finally take a couple of twigs and use them as toggles to tie to the ends of the elastic on the sides and pass them through the side tie outs. These will also be a bit loose.

The entire quilt is now secure. It will take a little practice to get the correct lengths, and if you wanted to add some plastic hooks later once you have it figured out, then that would probably speed things up a bit. If the quilt is a little slack under the hammock, don’t worry, under weight it will tighten to your back. The Quilt will pull into a hexagon shape under weight with the center expanding to about 34”, but you will still have ¾” directly under your back and shoulders.

[SGT Rock]

There hasn’t been a lot of cold weather here to test the quilt, but there have been some nights where the temperatures have gotten down into the mid to upper 30’s. On these nights I tested the quilt by wearing only a long sleeve shirt and a pair of nylon running pants.

The first night I tried the quilt, I used it with a car sunscreen on the inside of the hammock and the temperatures were as low as 37 degrees. By the morning, my back was sweaty and cool against the sunscreen, but not cold enough to wake me up.

The next night the temperature was about the same, but I left the sunscreen out, sleeping in just the hammock and quilt, which was very comfortable. I slept fine all night long despite the temperature being a degree or two lower and a slight breeze blowing around me. I was sold on the hammock quilt on that test.

The major concern I have had is rain splashing the quilt. I figured I would have to design a tie on barrier out of Tyvek or mylar that could double as a splash guard and a ground cloth for when I had to use the hammock as a bivy tent. But we had another night recently where the temps were around 39 degrees with 40-knot winds and hard rain. The wind and rain manhandled my tarp and got me a little wet until I got up and changed the pitch for the storm. In the morning my quilt was dry on the inside by my body, with a little splash on the outside of the quilt - but no water soaking into the insulation. The only major difference I was using that night was a foam pad that I was testing for the shape.

Based on my experiences I plan to try and build a down under-quilt like CanoeBlue has displayed over on www.thru-hiker.com <http://www.thru-hiker.com>. For half the weight of my Thinsulate quilt, I can have twice the loft protected by a DWR shell. I think that using a draft tube like piece, I can make that same under-quilt design also double as a poncho liner, but that is something to try later when I get back.

By the way…

In case you think that the humidity and winds here in Baghdad isn’t a good test for the trail conditions of places like the AT, here is a picture of my hammock after a storm three months ago. If you notice in one of the earlier pictures, there is a cargo pallet under my hammock, which I put there as a pier to get in and out of my hammock after rain storms when the place turns into a swamp.

[schrochem]

Sgt Rock,
First of all thanks for all the information on your site and in this forum. I have been here countless times for information so thank you for providing it.
I have decided to invest in a Hennessy Hammock for a variety of reasons and look forward to receiving it (B-day gift :))
Anyway, I have been reading about staying warm and like you've said in this post, an underquilt seems the way to go. I just posted over on whiteblaze the same idea, but noticed you mentioned the possibility of using tyvek in the underquilt. Do you think there would be added benefits of using aluminized tyvek for its reflective properties.
Just tossing the idea out there, b/c I am a pretty cold sleeper and was hoping for a feasible (and light ;)) solution to start with.
Thanks,
scott

[SGT Rock]

I tried to answer this while I was in Baghdad and had no luck.

I presonally think that aluminized tyvek wouldn't help any at all.

[brian]

Im going to start experimenting with making down underquilts. Ive got the down (FF 800 fill...paid $4 an ounce instead of $8), no-see-um netting, and I just ordered some 1.1oz ripstop. I will be posting my results of my projects here:) Hopefully I can learn fairly quickly how to handle the down...and get it right the 1st or second time.


Rock, are you still interested in a tarp when you get back (for good)? I can probably get you whatever color (solid) you want for no additional cost. Or the silver grey which I make all my tarps out of.


Brian
oes "at" hvc.rr.com

[SGT Rock]

I am highly interested in it. If you figure out how to make an underquilt and decide to start selling those, let me know too.