This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ainer and the
gross weight of the container and its contents. Planners find this calculation useful for designing anchors,
but it should not be relied upon for actual emplacement. To avoid hurried improvisation during
emplacement, emplacers should always test buoyancy in advance by actually submerging the weighted
container. This test determines only that a submerged cache will not float to the surface. Emplacers may
need to attach additional weight to keep the container from drifting along the bottom. As a rule, the
emplacer should add at least 1/10th of the gross weight required to sink the container and even more
weight if strong currents exist in the area.
D-98. Planners must first determine the submersion depth of the container to calculate the water pressure
that the container must withstand. The greater the depth, the greater the danger that water pressure will
crush the container. For instance, the standard stainless steel burial container buckles at a depth of
approximately 4.3 meters. The difficulty of waterproofing also increases with depth. Thus, planners should
only use the minimum depth necessary to avoid detection. Generally, 2.2 meters is the maximum advisable
depth for caching. If seasonal or tidal variations in the water level require deeper submersion, planners
should test the container by actual submersion at the maximum depth it must withstand.
Depth of the Water
D-99. Emplacers must accurately measure the water depth at the emplacement point. If planners design the
cache to rest on the water bottom, this depth is the same as the submersion depth. Planners may design the
container for suspension some distance above the bottom, but the emplacer must know the depth of the
water to determine the length of moorings connecting the container to the anchors.
High- and Low-Water Marks
D-100. Emplacers must estimate any tidal or seasonal changes in the depth of the water as accurately as
possible. They must consider the low-water mark to ensure that low water will not expose the cache. D-16 TC 1...
View Full Document
- Winter '14