Monday, March 03, 2008

Back to the Future - SUL - SUL Bottom Insulation for a Hammock

Back to the Future - SUL - SUL Bottom Insulation for a Hammock

Sleeping Pads as Clothes.

I really like sleeping in my hammock. My SUL - Cuben Hammock "hanging" weighs in at about 7 ounces. That in itself is very light, however, it is almost always necessary to add some type of bottom insulation to the hammock to keep my backside warm.

It is easy to just throw a sleeping pad into the hammock and climb in. The sleeping pad normally squirms and wiggles until I get settled and then I seldom have any problems with it.

If I wanted to add a bit of extra weight (NO) I could make another hammock with a double bottom and slide the sleeping pad between the two pieces of fabric that the hammock is made out of. This works really well and a lot of hammock users do the double bottom trick. Even if I used another piece of Cuben fiber it still adds weight to my gear list.

I have been spending a lot of time in my Cuben Hammock lately trying different sleeping pads when it gets cold enough. If I do any hiking this year is will be between late spring (end of April) to early fall (early Sept). I don't expect really cold weather during this time and may not see anything much below 40 degrees "F". I have been testing with one or more Gossamer Gear pads as necessary for what ever the temperature happens to be outside.

I was laying in the hammock early one morning and saying to myself "think what to do - think what to do". If you recall that is what the "little man" kept saying to the guy trying to defuse the bomb in Mel Gibsons car in "Mad Max Beyond Thunderdome". One of my favorite movies.

I have tried a lot of weird and funny things in my quest to make my gear lighter. What I decided to try was sewing pockets into the back of a set of hiking pants and shirt and cutting my sleeping pad into pieces to go into these pockets. My rational was that if this worked I would reduce the sq inches of sleeping pad by some amount and that amount would be weight saved. If this worked I would also get rid of all the squirming and wiggling of the sleeping pad when I get in or get out of my hammock. There are several other minor side benefits that I will not go into at this time.

I had a pair of pants I had used for a patten to test this idea with. I made a pattern for the sleeping pad pieces for both my legs and for the butt area and cut them out. I then sewed two pockets on the back of each leg (one above and one below the knee) and one larger pocket across the back (butt area). The sleeping pad pockets are on the inside of the pants and shirt. I did a test fit, put the pants on to see how they felt. Ok so far. I then found an old shirt and repeated the process.

With the sleeping pad pieces in both the pants and shirt I got into my hammock. It was only about 50 degrees "F" but my backside was warm enough.

The idea works and I was able to reduce the amount of sleeping pad sq inches by about 40 to 50 percent. The weight of the sleeping pad pieces used in this way add up to 4.157 ounces. This weight might come down just a bit when I get another 3/8" pad from Gossamer Gear and replace the blue pad pieces with it.

What is equally important is the ease of getting in and out of my hammock and having the added insulation in my shirt and pants for sitting around camp or wearing the extra insulation during the day if necessary. The pockets are just a little big so I have enough room if I had to double up my sleeping pad pieces or use a thinner pad as the weather requires. I am going to add another small pocket on the outer edge of my legs so I could lay on my side if I wanted to.

I can see many benefits and have several ideas to try and I also have a few for really cold weather but will leave that for another time.

I have a few pictures of what my first prototype looks like. For the leg pads I am using some blue Wal Mart sleeping pad as I didn't have enough extra 3/8" Gossamer Gear pad.

For a real test version I will use some Pertex Quantum for the pants and shirt.


Blogger samh said...

Bill - Why Pertex? It is the obvious choice for breathability but what about durability? - Sam

Monday, March 03, 2008 12:25:00 PM  
Blogger gerzson said...

For the hammock why don't you use the hammock through sleeping bag method. This way you will have insulation above and below, provided by the sleeping bag. No pad needed at all. I've been sleeping this way down to -20C.
At first I've put the hammock through the head opening and having a double zipper the foot end went out through a small opening at the that end. In the last years I have made small cuts in the hood and foot end to let the hammock in and out. This worked really well.

Tuesday, March 11, 2008 1:51:00 AM  
Blogger gardenville said...

To Sam,
I have the Pertex and breathability and light weight of the material is important in this application.

You know for me it is all about weight and hiking on the AT isn't like bushwacking.

My pants and shirt pattern are very simple ones and easy to make or to make a new one if I wear the first one out. On a really long hike I would have back-ups of all my major gear items in case I needed to replace something or just change it out as it gets warmer or cooler.

Durability to me is like condensation, I just deal with it if when I have to. I do carry a small repair kit and can make some repairs on the trail.

To gerzson,
I know that there are a lot of ways to stay warm in a hammock. I have tried many of them over the years. Most are bulky and heavy. They also are almost always a one purpose piece of gear.

To reduce my pack weight I try and have as many multi-purpose items as possible. I sometimes come up with things that may seem weird but I don't care about that as long as it works.

The bottom temperature I am looking for with this idea is about 40 degrees "F" or about 5 degrees "C". When I need to go below this temperature range I go to a Down Air Mattress for bottom warmth in my hammock.

Wednesday, March 12, 2008 10:52:00 AM  
Anonymous Anonymous said...

you are an inspiration, for sure !

This winter I have become a "hanger" and purchased a new sewing machine. Gish, am I having fun.

I do think it's time to stop searching WallMarts for rip stop $1.00 a yard fabrics tho.

I'm thinking my next project will be a cuban tarp to cover my hammock.

What is your experience with Cuban tarps? My design is 8' x 10' that I can close the ends with a blowing rain strom.

And where are you purchasing your Cuban?

Thanks for what you do ... especially lighting up the web with your fabulous photos.

Indiana Dave

Saturday, March 22, 2008 11:00:00 AM  
Anonymous Anonymous said...

I've been searching your sites for where you suggest one purchase ultra-lite fabrics such as cuben fiber. NO can find. Do you have your sources posted somewhere?
New sewing maniac and "hanger"

Monday, March 24, 2008 4:25:00 AM  
Anonymous Anonymous said...

why not make the pockets from:
- soft mesh
- attachable/detachable with un/tying short cords.

BTW, one of the best blogs, keep going & thinking. You can go lighter. I'm trying.

Friday, March 28, 2008 1:25:00 AM  

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