View Full Version : hennessy underquilt project

06-01-2003, 06:28
After a lot of reading and thought I concluded that an underquilt was the best way to insulate a hammock so I started some experimentation.

The first problem was to find the correct shape/pattern to make the quilt. I used some cheap polyester material and 1 inch foam for the test and was very pleased with the results. No more pad inside to deal with and no cold spots to worry about.

Using what I learned from my prototype I converted a cheap sleeping bag into a underquilt as follows...


determine and mark both vertical and horizontal center lines. these are used as a referance for all other markings.

along top and bottom sew a single line about one inch in.

for a 4x9 ul asym the quilt needs to be 47" wide or so. from the longwise centerline mark each side 23". sew a single line here to trap the insulation and cut the excess off leaving a one inch margin (24)

after both sides are done you should have a 48 " wide piece with the zipper removed and about 1 inch of loose material all the way around.

The next step is to make 2 v shaped cuts on each end to gather the ends together. (it is easier to make a v now and cut it out with the foot end then try to install one later.)

mark a line 9 inches inside of each of the longwise lines sewn earlier or 13 " from the longwise centerline. It should run from the bottom or top edge inward for 30 inches parallel to the longwise centerline. on this line mark a point 24 inches from the outer edge of the bag.

for each of the four lines fold the piece in half and flatten best possible. At the outer edge mark 4 " from the seam just formed. Using a straight edge create a triangle and mark/sew. cut off the excess material and finish joint with a cap piece or oversewing.

at the head end along the longwise centerline make a similar v cut stopping 12 inches from the shortways centerline. Use the same 4" width for this longer triangle.

If I have explained this correctly you should see a distinct football shaped curve present with one cut obviously missing.

On the original I cut a slit 6 inches off the center and ran down the footend longwise centerline. Then I sewed the end tips together so it worked just like the opening on the Hennessy. It worked fine except I could figure out an easy way to finish and reinforce the inside end of the cut.

For this prototype I marked, sewed and cut away half of the left side at an angle so the quilt can be pushed aside again leaving a one inch margin. I started the cut at the outer edge 12 inches from the shortwise centerline and ran it down and in to a point 24 inches from the shortwise centerline on the longwise centerline. This left a 12 inch end peice where I normally would park my feet. The exact cut has not been determined and needs to be experimented with yet.

As you may have noticed there are only two things left to do. Install a system to fasten the quilt to the hammock and finish the outer seams.

For mine I sewed loops on my hammock spaced 12 inches apart along the joint between the netting and the botton. Along the edge of the quilt I sewed loops of 3/4" elastic arranged to fall inbetween the loops on the hammock and attached the quilt to the hammock by running shock cord though each loop running along the side and tying the ends off to the main hammock support ropes. I also knotted the shock cord at the ends of the quilt so that it could be pulled tight. Safety pins could be used instead of sewing loops If your squeemish about sewing the hammock itself.

You could also use elastic and clips for attachment but I havent tried this arrangement. You may need to make the quilt an inch or two narrower to allow the elastic some stretch room.

Once you have determined how your going to attach the quilt finish all outer seams and inspect.

The original bag for this try was a 20 dollar el-cheapo with 3 lbs of hollow fiber fill and had a starting weight of 3 lbs 12 oz. The finished weight for mine was 1 lb 8 oz. and should be suitible down to 30 degrees (maybe). A better bag may have yeilded improved results but I havent had to confidence yet to chop up an expensive one to test. It may be possible to Use this with a mummy bag or a down bag but I would try the elcheapo version first.

more then one quilt can be used at one time to increase tempature rating.
The bag I used was 75" long but length doesnt seem to affect the overall fit that much. For other sized hammocks the size of the triangles can be increased to tighten the fit or elastic installed at the head end.
On mine I had intended to add a space blanket inside of the bag and removed the stitching used to stabilise the insulation. After I was halfway done I realised I had forgot to put the blanket in....DOH!

06-03-2003, 12:57
Sounds like a great plan. I've been using an old cheapo sleeping bag for a quilt myself. My summer weight bag's zippers blew out about the second season so I cut away the zipper all around and left the elastic bands on that were used for rolling it up. When I'm hammock camping it's a fairly easy move to tie these bands to the foot end of the hammock and then wrap the bag around you diagonally (like a wonton).

08-16-2003, 00:44
Very nice description....I just posted about buying a down comforter at Overstock.com and applying the process...thanks for the 'how-to'.....I'm thinking a down-underquilt for temps to 20degrees should possibly weigh in at 10-12oz....any thoughts on this or is it pie in the sky?

08-16-2003, 00:49
sounds very doable... let me know how it works

08-16-2003, 02:18
D.O.M.....so far I am satisfied with my sil-nyl taco and the Radiantek liner in it...it too has a slit that matches up with the HH slit....the Golite Fur would certainly do when the temp drops but like a lot of us I want a down model to save the ounces....I will report.

09-27-2003, 05:00
just a followup on the quilt...been overseas for 3 weeks but am soon to return to the underquilt project in down...contacted Nunatak Gear and they said to send them a model and they would gladly reproduce it in down and shell material of your choosing...they warned me it would be expensive but that a 10-12oz underquilt should be doable

09-27-2003, 13:11
sounds interesting, Im on hold for now as it is too warm out to do a proper test...

09-28-2003, 17:01
Make sure you get plenty of pictures.

09-28-2003, 21:40
speaking of pictures....i already have many of the 'taco' and the golite fur but when i tried to upload them they were all too big, these pics were from a real camera (advantix film) that I developed at Walmart and had loaded onto CD.....I guess I need to use the digital camera and set it on the smallest size?
also took a pic of of the Golite Cave in use above the HH I wanted to share but also too big to upload.

09-28-2003, 22:37
Originally posted by Simva the Medicine Man
speaking of pictures....i already have many of the 'taco' and the golite fur but when i tried to upload them they were all too big, these pics were from a real camera (advantix film) that I developed at Walmart and had loaded onto CD.....I guess I need to use the digital camera and set it on the smallest size?
also took a pic of of the Golite Cave in use above the HH I wanted to share but also too big to upload.


What I do is use software to process my digital pictures so that the image size is smaller. I reduce the quality as well so that the overall file size is acceptable for uploading to this site. I am no expert on this, but the software I use can be found at http://www.irfanview.com/. After you have downloaded and installed it, somewhere in the menu list is a 'batch processing' option that allows you to do this. I suspect that other people have different software to do this and some may be better/easier to use.


09-28-2003, 22:51
Tell me this, if i get this software can it modify a file off a the cd's I mentioned that were processed by Walmart? If so I am in the game.

09-29-2003, 06:53

I would think so, it handles all the different formats that I have had a need for. It doesn't cost any money to try it out.


Rain Man
09-29-2003, 12:27
Originally posted by Simva the Medicine Man
Tell me this, if i get this software can it modify a file off a the cd's I mentioned that were processed by Walmart? If so I am in the game.


Are you sure that your photo CD you get back doesn't have some photo editing software already on it? I thought they all did.

If not, there are plenty of freebie and cheap photo editing softwares out there. Once you get some (if not already on the CD), adjusting the pic pixel size and the file size too are slam dunks.

You do not need a digital camera to edit digital photos.

Rain Man

09-29-2003, 21:45
Well if it is on the Walmart CD already then I will be really embarassed! I will play with it when I get off this week. Thanks
to all.

09-30-2003, 23:22
After using the underquilt that I described in http://iemedia.ca/dk/home.htm in a wide variety of conditions I am more convinced than ever that underquilts are the only way to go with Hennessy Hammocks.

I use a larger fly than normally supplied with the H-Hammocks, and with the dwr outer layer, rain has not been a problem. Nor has condensation, which was a problem for me with the reflective pads or a Z-Rest inside of the hammock.

I don't know what the comfort range of an underquilt like this is, and certainly it is affected by whatever else you are wearing while you sleep, but I haven't found the limits yet (not sure that I want to either).

I just returned from a canoe trip that served up a variety of nasty weather, with sleet, high winds and temperatures low enough that my socks froze on the line. I was sleeping with a home-made quilt similar to the back-country blanket on top, and the underquilt below. On the coldest of the nights I added woolen long underwear and a light jacket - and ear plugs to block the howling of the wind. In conditions like that perhaps a little thicker fill would have been in order, but this has not generally been a problem.

FIT of the underquilt is important. On the few occasions in high winds that a gust would find it's way between the hammock and the underquilt I could feel the chill. It didn't happen often and it was only fleeting - but it was enough to make the point.

10-12-2003, 06:00
I know what you mean about fit being important -I string my quilt to the hammock with bungee cord so it is held against the bottom tightly.

I recently had a chance to try out a new cut for the quilt and it seemed to work well with no noticable cool spots. instead of a split for the opening I went from halfway up the opening to the mid point of the quilt on the diagonal. a cleaner cut might be a curve from the bottom end center point to the a foot below the mid point on the unused side but I was being sloppy..... The cut knocked a few extra ounces off and I didnt notice any differance as I never put my feet over there anyway. Cant wait for real winter to get here :D

as to comfort I didnt notice it being overwarm as I just vented with the blanket... I suspect there isnt a too warm under quilt - just too-cold ones.

:-? :banana :cool:

10-12-2003, 07:26
I did have a too warm experience with the underquilt...it was the modified Golite Fur suspended underneath via a taco and it was July! My back and the bottoms of my legs were sweating like pigs but my chest was cool via a breeze....
you have to admit it is a fun puzzle to try to beat, using the hammocks in cold weather

10-13-2003, 12:24
fun yes but still a ready made package would be nice

10-13-2003, 23:03
D.O.M.....I'm thinking that premade package is the Speer deal, I just dont want to pay that much if what I've got can emmulate same...plus I think his Pod is too heavy for the temp rating (and the price)-thinking he should offer it in down for the weight savings and temp increase....the Crazy Creek Crib has shipped so by the end of the week I will know if the WM Ponderosa is big enough to wrap around the hammock with no compression....
so the numbers are:
Ponderosa 2' 14oz
Crazy Crib 16oz
Close Cell Pad 5oz
GoLite Cave 18oz
___________________total 6' 5oz.....

my fingers are crossed that the Ponderosa and the Crib will
work....6' 5oz. is a touch heavy but we hammockers have agreed that awesome comfort has a price.
Compared to my Spring,Summer,Fall setup:

HH 1' 15oz
Arc Alpinist 1' 4oz.
Underquilt 16oz.
Golite Cave 18oz
_____________tot. 5' 5oz.

So a pound more for winter use, the extra foam pad is with me anyway in shaping the Mithril or the Speed, and I haven't included the weight of the WM Flight I have always carried and used as extra insulation in the taco/underquilt since it will be carried year around.

If this was the past (i.e. sleeping on the ground or in a shelter) and using the Arc Alpinist and a closed cell pad and the Cave I would have a sleep system at 2' 4oz, looking at the numbers the weight difference is hard to swallow but waking up with the back of a newborn when hiking instead of someone in a body cast is worth it.....

10-27-2003, 00:10
Helpful directions from Dirtyoldman. Here is the way I made a template for the quilt: Using a door knob and a sturdy piece of furniture, hang the hammock in your living room. Take a piece of a plastic drop cloth found in the paint section of a hardware store. Drape it over the center line of the hammock. With a magic marker or pen, trace the outer edge of the hammock on the right then left side of the center line. Remove the plastic, lay it flat, and cut out along the magic marker lines. You have what looks like a large turtle's shell. Draw straight lines to sqaure off the ends. Check out the measurements next to those suggested by DirtyOldMan. Voila! PS The only concern I have about a down underquilt is rain.

10-27-2003, 00:30
concerning rain and the underquilt, use Pertex as a shell (if you can get it, check with OWF), and (though a weight penalty of around 8-10oz) you could also use a sil-nyl taco under the down underquilt for gauranteed waterproof/windproof underlayers...

SGT Rock
10-27-2003, 03:30
I've been playing with an underquilt although it is way too hot here yet.

I took a thinsulate poncho liner and folded it into thirds. This gives me about 1 1/2" under the hammock in a 27"x60" underquilt and the ability to use the liner under a packa or as a blanket poncho in colder weather. I plan to replace the tie strings on the liner with elastic when it gets here. According to the highly inaccurate scales I have here the liner weighs about 19.6 ounces, but I think is is lighter than that.

On the hammock I sewed 5 buttons as attaching points. I plan to replace these with cord or elastic. I put them into place by pinning a safety pin in the correct spot from the inside while laying in the hammock. To ensure it was correct I tied the liner to the outside. I always lie in the same spot inside the hammock so this gives me a good wide spot. My feet don't seem to need extra insulation and I usually use a filled stuff sack for my head, so hanging off both ends insn't a problem.

Then I took a space blanket and cut it 29"x62" to hang under the blanket and reinforced it with 100mph tape. This will serve as a wind block/vapor barrier/splash guard on the hammock and also serve as a ground cloth if I need the hammock like a bivy. I figure it weighs about 4 ounces. I may replace this later with a sil nylon piece about the same size for better durability at about the same weight.

Then I have a trimmed Army closed cell foam pad. The weight on the innacurate scale is 17.3 ounces.

I figure the system should work something like this:

50+ just a liner as a blanket inside the hammock with the groundcloth as a backup.

30-50 Pad and down quilt with the groundcloth as a back up.

below 30 under quilt, pad, groundcloth, and down quilt. If it is below 30 in camp I can use the poncho, liner for clothing until bed time then hang it for extra insulation. This makes the under quilt a dual use item. I have a little bit of sewing left to finish before I get some pictures made.

It may not work at all, but it is fun to play.

I have also been experiementing with some new tree hugger straps I had made.