In 1942, Waldemar Semenov and the crew of the Alcoa Guide, an unarmed merchant ship positioned about 300 miles off the coast of North Carolina, found themselves in a tight spot. A German U-boat had surfaced and opened fire, using the ship as “target practice,” according to Semenov. With the ship aflame and on the verge of sinking, Semenov and some of his crew managed to get to the lifeboats. Using a small compass, the survivors sailed west by northwest for three days until they were rescued by an American destroyer ship. Semenov’s compass is now on display in the National Museum of American History.

Even if you never find yourself in escaping enemy fire on the high seas, Semenov’s story is a testament to the importance of the compass. While modern GPS units have made navigating the wilderness easier, many experts recommend the tried-and-true method of a compass and map for navigating the backcountry, or, at the very least, they suggest it as a backup to an electronic navigation system.

But what if you find yourself in an extremely unlucky situation where your compass becomes lost or broken and rescuers won’t know where to find you? There’s the old moss trick, of course. But that’s fairly unreliable. Turns out that a traditional, analog watch outdoors can double as a compass. Using one as such is an old trick that’s even taught in the U.S. Army Ranger Handbook. In fact, some watches even feature a compass bezel that makes the process easier, though any analog watch with a 12-hour scale will work. It isn’t perfect, but it could still mean the difference between life and death. That counts for something.

If you’re in the Northern Hemisphere, find a nearby area with a clear view of the sun. Take off your watch and hold it horizontal in your hand so the twelve o’clock marker is facing left, then point your hour hand in the direction of the sun — true south should be located approximately between the hour hand and the twelve o’clock marker. Before noon, you’ll need to measure clockwise from the hour hand; in the afternoon, measure counterclockwise from the hour hand. So, for example, if it’s four o’clock in the afternoon, point the hour hand at the sun, and south should be located at the two o’clock marker. If it’s noon, the hour hand will be pointing south.

If you’re in the Southern Hemisphere, the method is essentially inverted. You’ll find a spot with a clear view of the sun, take off your watch and hold it horizontally, but you’ll point the twelve o’clock marker towards the sun. North should then be at the midpoint on the watch between the twelve o’clock marker and your hour hand.

For more accuracy, the U.S. Army Ranger’s handbook recommends placing a small stick in the ground, which will cast a more definite shadow. The process is otherwise essentially the same, but instead of pointing the hour hand or twelve o’clock marker towards the sun, you’ll point it towards and along the stick’s shadow. This process takes slightly longer but if time is on your side, it might be worth it.

Keep in mind that this method only works during the daytime when the sun is visible. It also will only work in the temperate zone, as the closer you get to the equator, the harder it is to discern the movement of the sun. Also be mindful of daylight savings time. If you’re currently practicing it (i.e. during the summer months), either set the hour hand back one hour or use the midway point between one o’clock and the hour hand instead.

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