In a hammock, you’ll need bottom insulation, when you used to sleep on the ground this was taken care of by your sleeping pad (inflatable or closed cell foam), and if you like you can use it in your hammock as well.
You might think “i don’t need any padding in the hammock, and I have a very warm sleeping bag also, so I don’t think i’ll need any bottom insulation”…Well, Think again. If your sleeping bag is made of compressible insulation (like down or highly compressible hollow fiber synthetic) the part underneath you will compress to almost zero thickness wherever you are laying on it, rendering it mostly useless in those locations, and the more compressible your sleeping bag insulation is, the less it will insulate where it is compressed under you.
In general, without any real bottom insulation under you at all, you’d start to get a cold backside after a few hours in temps as high as the high 60’s and low 70’s. It gets this cool on many summer nights so you’ll normally need something for bottom insulation year-round.
Your three options are: closed cell foam pad, inflatable camping pad, or an underquilt. They each have their pros and cons…
An underquilt is used as bottom insulation as a replacement for a sleeping pad. It consists of sleeping bag insulation that is suspended underneath the hammock where it can insulate the bottom of the hammock without being crushed under the occupant’s bodyweight.
The “Yeti” is our torso-length ultralight underquilt. The idea is that many backpackers are already carrying a short piece of ccf foam anyway to use as a sit pad, pack frame, fire fanner, emergency go-to-ground bottom insulation ect. As such, it can be used as bottom insulation for the lower legs as well and allow you to cut a good deal of bulk and weight from your underquilt (6-7oz). The leg pad and torso-length underquilt combine to give you full head-to-toe bottom insulation.
A short pad under the lower legs doesn’t come with the negative characteristics associated with full-length pads, such as uncomfortable pad buckeling, difficulty with proper placement, and bulkiness. In fact it’s so easy to deal with a pad under your lower legs that you don’t even need to bother putting it between the layers, in fact many find it easier not to. In warmer weather the torso length underquilt may be warm enough on it’s own without a need for a leg pad.
Many people prefer a full-length underquilt for it’s simplicity over a torso-length UQ plus leg pad.
The main downside to an underquilt is the cost (the weight of full-length underquilt is similar, possibly slightly heavier, to a similarly rated air pad, but UQ’s are often almost twice as wide as the air pad, not to mention convenience and comfort being much better with an Underquilt)
Pads (torso or full-length): You’ll want either high-quality closed-cell foam, or an inflatable.
CCF is available by the yard so you can cut it to your exact specifications and it’s cheap, however it doesn’t compress at all so it can be harder to pack and will have more issues with condensation on the warm side of the pad than an air pad or UQ. (check local upholstery shops for quality closed cell foam by the yard) If the foam is high quality, 1/8″ can be enough for summer nights, 1/4″ thickness for milder weather (down into the low 50’s), 3/8″ for cooler weather (to freezing or below) and 1/2″-5/8″ down into the single digits and below.
Inflateable camp mats are available at most outdoor camping stores and come in full-length and torso-length, the latter makes a good compact leg pad for use with a torso-length underquilt.
Most folks prefer an air pad to be only about half inflated when used in a hammock. Air pads are much more compressible than CCF but are also more expensive.
Full-length pads (ccf or air) can be tough to get positioned properly, and they buckle, bend, and poke near your hips (especially with end-gathered hammocks) and as result most people find them to be uncomfortable because of this. This is the only reason underquilts exist. (The Ridgerunner (bridge-style hammocks in general) are an exception to this rule, not suffering from these issues to a large degree). Inflatable camping pad normally come in 2 different widths, 20″ and 25″ wide. The 20″ width is very narrow for a hammock, and many feel the 25″ pads are only slightly better (an underquilt is generally 40″ or wider as a comparison)
As far as bottom-insulation goes, you can use any of the bottom-insulation options (ccf pad, air pad, or underquilt) or any combination of them to cover yourself from head to toe and stay warm at just about any temperature, provided you choose an appropriately rated pad or quilt for the air temp. (don’t worry about windchill, you’ll be blocking the wind with an appropriate tarp).
We recommend an underquilt for anyone using an end-gathered style hammock (if you can afford it). This includes the BB, the XLC, and our Traveler hammocks as well as end-gathered style hammocks from other manufactures. Alternatively, anyone using a Ridgerunner can pretty much use an underquilt or a pad with equal ease/convenience/comfort.
All prices are in USD