How to Turn a Watch Into a Compass
If you are in the northern hemisphere and your watch is still on your wrist (and still works!), the cardinal points can easily be deduced. Point the hour hand at the sun. Then form an imaginary line directly through the center of the "wedge" that is created between the hour hand and 12 o'clock. This is your south–north line. The height of the sun in the sky and the time of day will then show you which end of the line is north and which is south, remembering that the sun sets in the west and rises in the east. In the southern hemisphere, point the 12 o'clock mark at the sun and bisect that with the hour hand for the north–south line. (From his 2008 book 'Man vs. Wild.')
How to Build a Log Armchair Raft
This is one of the simplest and most effective flotation devices there is. Select two branches or the trunks of young trees. They should be as straight as possible and at least 18 inches thick. Lash them together with vines at both ends but leave about two feet of slack vine between them. Either cover this area with a tarp or sit directly between the two trunks armchair-style and float downstream. A long straight pole can be used as an oar: Either pole along or use it like a canoe paddle.
How to Build a Snow Trench
The simplest and quickest type is a shallow scrape deep enough to give protection from the wind and wide enough for air to circulate around you. The snow you dig out can be piled around the sides and compacted, then covered with a tarpaulin for a roof, which can then be covered with more snow. Leave one end of the trench open for an entrance and block the other with a rucksack or more snow. If the snow is compact enough, a more elaborate construction can be made by carving blocks of snow like thick paving slabs (about two feet thick). Lay them flat over the trench or lean them against each other for an A-framed roof that will give more headroom. If no tarpaulin is available and the snow is the wrong consistency for blocks, make a three-foot-diameter snowball, cut it in half, and lay both halves over a narrow trench. Then burrow in from one end and dig the trench wider the deeper you go.