Keeping Moisture Out and Letting It Out. One of the most perplexing problems for Backpackers (Scouts are no exception) is keeping things dry—both themselves and their gear. There is no one solution to this dilemma and you should not think to this problem as a single dimensional one. Rather, approach it as a multidimensional task and attack it on several planes at once. You must have multiple, redundant moisture barriers. Described below is "a system" of steps you can take to keep things dry. For example, the combination of properly fitted pack cover, water resistant pack fabric, and waterproof zip-lock bags provide good assurance against moisture spoiling hike in the rain outweigh the added weight of a few plastic bags. Besides, dry gear is a lot lighter to carry than that which is water soaked. You can be comfortable for a long time under adverse conditions with just a water diverting canopy (dining fly, tent fly, or poncho), and a dry sleeping bag to keep you warm and cozy. Without it you are miserable before very long and possibly at risk of hypothermia.
Things to consider about moisture (getting wet) while backpacking:
Water resistant pack fabric. Quality packs will have some kind of coating to make the bag moisture resistant, but don't count on it keeping everything dry by itself. Few packs totally waterproof, at least not at the seams and compartment openings, so a pack cover is a necessity. Further, the best assurance of dry food, clothes and sleeping bag is to pack them in zip-locked bags or "goose necked" plastic bags.
Pack cover. Your pack cover is one of those essential pieces of gear. It should always be readily accessible. Nylon coated ones are available in most outdoor equipment stores. In an emergency, even a heavy garbage bag can be fashioned into one.
Hang your pack under a cover. Water will run off. A pack on the ground may accumulate water. Below are photos of a completely waterproof way of hanging a pack or bear bag using a garbage bag, two feet of cord and a "bulb" end with a hole. The first one shows three types of "bulbs"; a plastic lid with a hole; a complimentary hotel shampoo bottle with a lengthwise hole (attached to pack); and an roll tape core. After the bulb is attached to the pack, the bag is placed over the bulb and pack and a rope is placed around the bag below the bulb (where it won't slip), then hung from a tree. Because nothing passes through the bag itself, there is no hole for water to get in. For an added measure of protection, use a long bag and tie the bottom shut.
Bear bag. Hanging the bear bag under a plastic cover can help keep contents dry. Contents that might be damaged should already be in water proof bags and the redundant layers will help. It will also discourage rodents from coming down the rope to the bag.
Ground cloth. A ground cloth under your tent does two things: (1) it provides a moisture barrier between the cold ground and your warm body and (2) it smoothes out any imperfections in the ground under your tent and helps protect your tent floor from jagged rocks and sticks. Here too, a military-type poncho is useful. It can be folded out nicely as a ground cloth for at two person rectangular tent (5'x7').
Sleeping pad. It acts as a moisture barrier, but also elevates you above any moisture that might seep into your tent. Self-inflatable pads are convenient and very comfortable but can be heavy, especially the full-length ones (2-3 lbs.). Closed-cell pads are light weight (10-16 oz.) and cost about one-quarter of what a self-inflatable one costs, however, they are bulky. Some newer closed-cell designs fold like an accordion. In spite of the weight and cost, I still prefer the self inflating variety; nothing beats a good night sleep after along day on the trail.
Avoid the low ground. Consider the terrain around your tent. Be careful not to set up over an indentation because water will accumulate there and standing water is likely to penetrate your tent before water that is running off. Setting up on a slight "knob" results in water running away from your tent. Also, be careful not to camp too near streams that could rise in a flash flood or where the valley is narrow but drains a large area. Although you want to avoid low ground, you may also want to avoid the tops of bald hills when there is the possibility of lightening striking.
Full-coverage tent fly. The tent fly puts a barrier between your sleeping compartment and the rain. Water will "bead" and runs off a properly coated and placed fly. This process is interrupted only when a "wick" is provided to draw the moisture through the minute fabric holes of the fly ("seam sealer" or "taped seams" is to block water from coming in around the bigger holes made when the fly was stitched together). An object pressing against the inner wall of the fly provides the "wick" to draw moisture in. A partial ("umbrella") fly leaves a single wall between you and your gear and the rain. Anything touching the wall will provide the wick to draw in moisture. Full-fly construction puts a full barrier between you and your gear and the wet fly. The full coverage fly also helps drop the water off a little way from the tent (which somewhat keeps it from running back under the tent). Full-coverage flies come in two general types of construction; one, like our Eureka's, use a tent pole attached to the fly across the top to create an "awning" over the door and rear window (for ventilation) and the other stakes the fly directly to the ground all around to create a covered vestibule (storage area) in front of the door. Full coverage usually costs a few extra ounces in weight but if you plan on a wet outing (or even if you don't) this is one of those really nice things to have.
Dining fly. A military-type poncho (with corner grommets) used in lean-to style provides an excellent dining fly (a small polyethylene tarp works well too but can add a little more weight to your load). Either way it is an optional item to take with you, but one which comes in handy for shelter when you need to wait out a flash downpour. During a persistent rain, this may be your only place to meet, prepare, and eat food. But don't even think about using your stove under a backpacking dining fly (e.g., nylon poncho); all fire sources should be kept well outside the edges of the fly.
Synthetic-fill sleeping bag. Don't take chances with keeping your sleeping bag dry. Use a synthetic-fill bags so that you can recover quickly if it gets wet. This is more in the category of "getting the moisture out" once it is in. Synthetic fill tends to dry quicker, retain some insulating properties even when wet, and retain less water weight than down or cotton fill.