The Hennessy Hammock Supershelter contains three components: an Undercover, an Underpad, and the Overcover. The Undercover is a waterproof, windproof, Silnylon layer that provides another layer of material under the hammock protecting your back from the cooling effects of the wind (9.0 oz). The Underpad is a foam pad (8.3 oz) that is sandwiched between the UnderCover and the Hammock, and the OverCover is a Silnylon layer that covers the no-seeum netting on top of the hammock (with the exception of a ventilation hole), blocking heat loss and providing another wind barrier.
I’ve tested the UnderCover and UnderPad on a number of long backpacking trips in Vermont and New York State over the past year in nighttime temperatures ranging from the mid-twenties to the mid-fifties (F), but I can’t say that I’m completely satisfied with them. I just received the OverCover from Hennessy and will be testing it when temperatures drop in a few months.
The UnderCover, like the Hennessy Hammock itself, has a birth canal style opening that you poke your head through to enter the hammock. To install it, you loop it under the Hammock and thread the Hammock ridgeline through its ends. There are elastic bands at the ends of the UnderCover that you then loop over the hooks attached to the ridgeline and adjust to tension it. The UnderPad shown in the picture below, is a foam pad that you roll up for storage in your pack. To install it, you unroll it between the UnderCover and the Hammock, again attaching elastic bands over the ridgeline hooks. However, unlike the UnderCover, the UnderPad does not have a birth style channel making it very awkward to get in and out of the hammock.
Hennessy claims you can just simply slide the pad out of the way to enter the hammock, but it is impossible to grasp it once you are inside without putting your hand right through the foam material, as shown in the picture above. Since you can’t reposition the pad, it stays under half of the hammock and you end up getting chilled at night.
After much experimentation, I discovered a solution to this problem. I fold the UnderPad in half and position the upper half that is located above the birth channel split, between the UnderCover and the hammock, as intended. Getting in and out of the hammock at night to pee is easy and I don’t have to fumble with the position of the UnderPad when I get back in. The area under my legs remains uninsulated but my sleeping bag has enough insulation to keep me warm. In addition, I don’t tie-in the UnderPad to the UnderCover using the hammock side guy lines and it stays in place. I’ve found that using the guy line tie-outs is a major contributing factor to UnderCover and UnderPad misalignment and you are better off not using them at all.
This layout works well down to the mid-thirties, except that in the morning, there is a noticeable amount of condensation on the inside of the UnderCover and soaking the UnderPad that you need to let dry or towel down before you pack up for the day. In colder weather, I also slip a small pad that I carry under my sleeping bag inside the hammock and under my back if I need a little more insulation under my core.
The lack of a birth channel and these condensation issues make the UnderPad solution a sub-optimal solution in my opinion. I like the JRB Nest, a down filled under quilt with a birth channel split much better for insulation down to the high thirties. I have not layered an UnderCover below the Nest yet, but plan on trying this later in the year.
Disclosure: The author owns this product and purchased it using their own funds.