Hammock Under quilt Project

Summer 2020 has involved a lot of domestic exploring. I bought a Hennessey Hammock early on in the season with the intention of spending more nights under the stars.

Hanging out under the trees.

I soon realised the need for some insulation from below. Even on warmish summer nights a little wind cools you down quickly when being suspended by a single layer of fabric. A regular sleeping bag was not ideal as you end up lying on and compressing the insulation, making you cold and vulnerable to gusts.

Searching led me to Reddit and the unsurprisingly amazing and detailed myog and hammockcamping subreddits with many stories of ‘cold butt syndrome’ (CBS) and ways of solving it.

My first attempt was with a number of reflective heat pads. Made out of the kind of material that you’d use in a car windshield reflector. I wanted to keep everything small and light so I opted for a number of smaller ones (intended for sitting on) and added some velcro fasteners at each corner so that they could be crudely linked into a reflective sleeping mat.

The pads addressed the problem of feeling cold against the hammock fabric, but didn’t exactly stay put during the night. Even the slightest movement or turn would displace some (or all) of them and you were back to being cold on a new body part.

I decided, eventually, on an under quilt. They seemed a little bulky to begin with, more potential weight and bulk to bring with me on a trail or bike. But reading more reviews and guides sold me on the idea. They’re simple to construct, fairly multipurpose (at the end of the day it’s just a light insulated blanket), and hopefully fun to make.

I became intrigued by the kit sold at Ripstop By The Roll for making an under quilt with Climashield Apex insulation. It seemed fairly cheap and easy to build and so I went with that (and their great instructions). Unfortunately, now residing in Sweden, it made it a little difficult to order from a US site, but the excellent extremtextil.de came to the rescue and I ordered everything there.

Materials/weight wise, I ultimately went with:

  • 133g/sqm, 4oz/sqyd Climashield Apex
  •  40den, 45g/sqm ripstop nylon in yellow (inside) and green (outside)

My plan wasn’t to make it warm enough to camp in the snow, but to make something suitable for 2.5 seasons.

Construction was quick, only taking a couple hours. The trickiest bits were manoeuvring the large swathes of fabric around the small sewing machine. Threading the grosgrain channels also proved a little frustrating on one side as I had made the channel a little bit too tight! But it was all solvable.

Linelocs to hold everything in place!

The instructions encompassed a nice amount of adjustment with linelocs and cord locks, so in theory this should be able to work with my asymmetrical hammock. The under quilt attaches to the hammock suspension with a simple carabiner at each end and then can be pulled tight and cinched as needed.

Small but functional!

With a little of the leftover ripstop that I have been amassing recently I made a simple stuff sack in grey and red to hold the quilt when in my pack. Total weight: just under 660g.

My first test was later that evening (on an unseasonably hot day which made the under quilt seem rather inappropriate). It was easy to set up, and seemed pretty warm from a first try – though the real test will come one night time soon.

The finished product!

I think that there may be future challenges keeping the quilt asymmetrically in place as it didn’t hang quite at the right angle. Looping the ground tie outs through the under quilt suspension make it a little better, but didn’t seem quite right, so I’m probably going to investigate adding some grosgrain loops along the long side to hook onto the hammock tie outs. Probably something I should have added during initial construction, but I will definitely consider it for a V2.

All in all, a great first under quilt. I still need to test the real world performance, but I have high hopes.

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