BYPASSING OBSTACLES USING THE DETOUR METHOD USMC
  1. During the planning stages of any mission, patrol leaders must always conduct a careful recon of the area the patrol will be moving through. Maps, aerial photographs, physical recons, S-2. and debriefs will provide the information needed to make a route plan.
  2. While moving toward the objective, the patrol may encounter enemy positions, danger areas, or natural obstacles of which there was no prior intelligence, forcing the necessity of a deviation from the course. The objective will be to bypass the obstacle and get back on the original course.
  3. The detour method to bypass obstacles is nothing more than a series of 90 degree right and left turns. A good working knowledge of the lensatic compass and pace counting is necessary to accomplish the bypass. If possible. the entire bypass should be calculated on paper in a secure position before actually conducting the bypass.
To conduct a 90 degree bypass, follow these steps:
  1. Record the primary route pace count and assign a pace counter for the detour legs.
  2. Determine the method that will be used to bypass the obstacle, right or left.
  3. If the obstacle bypassed is to the right, add 90 degrees to the present azimuth. If the obstacle is bypassed to the left, subtract 90 degrees from the present azimuth. A simple rule to remember is the acronym. RALS (right add, left subtract).
  4. Proceed on the detour azimuth until the width of the obstacle has been cleared. Ensure a pace count is kept on the detour leg.
  5. At the end of the detour leg, turn right or left (using RALS) to travel the length of the obstacle. This azimuth should be the same as the original azimuth. When traveling the length of the obstacle, the pace is added to the original pace count by the primary paceman.
  6. Once the length of the obstacle has been bypassed, turn left or right (using PALS) to travel the width of the obstacle again. This will be the second detour azimuth and it is a back azimuth of the first detour azimuth. The distance of the second detour is the same as the first detour leg.
  7. At the end of the second detour leg, turn left or right (using RAL S). This will be the direction of the original azimuth. Keeping track of the detour pace count will ensure that the sniper is at the spot where he would have been if he had walked right through the obstacle.
  8. The primary paceman still has a good count. The sniper should be on his primary azimuth. Now he can continue his movement.