There’s a number of different options here and I can honestly say we’ve thought about, designed, and tried a fair few now. The difficult thing to decide is ‘what works best?’
As I see it there’s 3 choices;
- Toughen up! (Not my favourite option)
- A hammock underblanket of some sort
- A roll mat
The underblanket and roll mats both have their pros and cons and depending on your weight/size restrictions they can range from sauna like to a bit chilly.
The roll mat is a simple solution and cheap, lightweight and reasonably easy to carry around. It doesn’t matter if it gets wet and is versatile. In the hammock it provides good insulation on the bottom of the hammock and as long as you’re lying on it you’ll be relatively warm. My first night in a hammock was on a single closed-cell foam mat. The biggest downside I found was that as it’s only a single mat you could easily slide off it through the night. The width of the hammock obviously being wider than the mat meant it moved around quite a bit and when you’re arms/torso came in contact with the outer hammock they soon got cold. I did try a double self inflating mat which was the same size as the full width of the hammock thinking it wouldn’t move around and could wrap round me better. In the centre of the hammock it worked great but at each end where it bunches together the width of the mat just made it pop out and became very annoying. Got up twice through the night to put it back in place. Maybe a double closed-cell foam mat cut to shape a bit would work, but I’m tired of trying mats and think there’s a better way.
Moving on to the underblanket which is a much more complex and far reaching option. As most of us with hammocks are doing so to reduce weight and bulk of our kit let’s set the criteria as aiming for the lightest option providing most warmth. Bear in mind I personally think this is the holy grail of ‘hammocking’ and it’s very difficult to achieve the ultimate in both at the same time.
Underblanket Mk1 was one Michael made which is a good 3/4 length underblanket in full DPM Gore-Tex material. It’s the one Chris used on our 2nd Kielder trip and did keep him warm down to around 0 degrees with the only downside of your feet get a bit cold and it’s pretty bulky. It has toggles at the centre on each side which can be tightened to lift the underblanket up which should make it warmer. The thing we’ve learned from this one was shock cord used all round the underblanket gives way too much stretch and it is difficult to get it to fit really snug against the sides of your hammock so looses a bit of warmth.
Mk2 was a simpler design using an old sleeping bag and down filling from a pillow. Another 3/4 length underblanket but this time made with little pockets of down which reduced the size considerably. The shape was also changed slightly on this one to try and fit closer around the hammock. Again though the limitation is the length and still not fitting brilliantly against the hammock with the shock cord.
In between Mk2 and Mk3 we experimented a little and made a full ‘pea pod’ system which was made from a very thin sleeping bag but as it was full length and sealed felt very warm. It must be said it hasn’t been tested overnight though. We’ve also bought some emergency blankets (the shiny foil kind) and were very surprised at the heat that radiated back in them. A fleece blanket was also tried in the bottom of the hammock, however just moved around and folded up too much to be of any use.
Mk3 underblanket is now almost finished, which started life a two sleeping bags. Measuring approx. 190cm in length one full plus half of the other gives a full length underblanket for our 2.7m DD Camping Hammock. Stitched together and left in a basic rectangular shape to copy the shape of the hammock will hopefully mean that once each end is gathered it created a tight fit against the hammock sides. And at only 5cm narrow in width should cover all of the sleeping area. If it still gapes a bit we’re going to add small loops to the hammock sides and toggles along the underblanket which would hold it in place.
Mk4 is already in design with some additions to the Mk3 version. These being a windproof/waterproof cover for the outside with one of the emergency blankets stitched to the inside to give multiple layers from outer to inner of windproof/waterproof – heat reflector – insulation – warm air – hammock. Sounds like a winning combination to me! The plan is to also make this one with down filling for extra warmth while being able to compress more than synthetic materials.
With each underblanket revision we’ve learned some important things along the way; it needs to be well fitted against the hammock sides, full length is better than 3/4, down compresses more than synthetic, limited shock cord use provides more structure. Our solutions are getting smaller and more compact each time as we find new and more effective ways to add warmth without the bulk. Will be back with photos of Mk3 and Mk4 when they’re finished and a review of what works and what doesn’t with… One thing being certain, we’ll be testing these properly in May on the canoe trip.
