A lightweight poncho or tarp, brightly-colored, with grommets or tie-down-loops spaced around the edges, is an indispensable item. It can be used in so many different ways, limited only by the user’s imagination:
A poncho is basically a tarp with a hood sewn into the center, and snaps or fasteners down each side. The allows a user to wear it for rain or wind protection, yet also employ it for tarp-like duties if needed.
A bivy sack, as intended, is a wind and water-resistant outer layer designed to go over a sleeping bag. As any outer layer should, bivy sacks trap body heat for warmth, and help keep the wearer dry if the environment is damp.
The perfect bivy sack is constructed of a durable fabric such as nylon or woven polyester that incorporates a breathable membrane such as Gore-tex or Dry-Plus.
Choose a lightweight sleeping bag with a woven nylon or polyester shell, and synthetic insulation. Down-filled bags, while lighter, must be dry for insulation value. When wet the down turns into a useless, soggy mess.
Bags have minimum temperature comfort ratings. Note that using a bivy sack makes a lighter bag warmer. Choose a rated bag accordingly.
A ground pad is a padded, water-resistant insulation barrier between the body and the ground. Ground pads aid in preserving body heat for warmth, and provide comfort if the ground is hard.
Most lightweight, inexpensive ground pads are constructed of closed-cell plastic or rubber foam, are full or 3/4 body length and width, and are around 3/8 to 1/2 inch thick.
The generic term space blanket applies to multi-use blanket-size squares, rectangles, or envelopes made of thin, synthetic material, silver-shiny or “reflectorized” on at least one side. In theory, the shiny side, when facing the body, reflects a high percentage of body heat back to the wearer.
A space blanket is lightweight, waterproof, and windproof, all necessary shelter qualities. It can be used as a shade cover, reflecting the sun’s heat with the shiny side facing out. Additionally, the shiny side is highly visible to aircraft and ground searchers.
A standard, full-size blanket is constructed of durable, reinforced material, and has grommet holes for use as a tarp, barrier, or shelter-fly.