1. The ideal beach for landing craft and amphibian operations is one with deep water close to shore, a firm bottom of hard-packed sand and gravel, minimum variation in tides, and a moderate to gentle (1:15 to 1:60) underwater beach gradient. It also has no underwater obstructions to seaward and no current or surf. Although such a beach will be rarely exist in the area of operations .
Beach Composition
2. Beaches can be classified according to the surface materials which it is made of silt, mud, sand, gravel, boulders, rock, or coral, or by combinations of sand and boulders. The ideal composition for beaching landing craft and amphibians is a combination of sand and gravel. Silt, mud, or fine sand may clog the cooling system of landing craft. Rock, coral, or boulders may damage the hull or the underwater propulsion and steering mechanism. Firm sand provides good beach trafficability for personnel and vehicles. A beach is usually firmest when it is damp and when the material is of small size Gravel has good bearing capacity but poor shear strength. As a general rule, the coarser the materials, the poorer the trafficability.
Beach Gradient
3. Beach gradient or underwater slope is expressed as a ratio of depth to horizontal distance. For example, a gradient of 1:50 indicates an increase in depth of 1 foot for every 50 feet of horizontal
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Waves are created by local and offshore winds and other meteorological phenomena. There are two types of surface waves called wind waves and swells. Wind waves are generally steep with a short period and most of the time crests break in deep water. Swells cause from storms distances from the coast. Swell have a long, smooth surface and these waves never break in deep sea. Swell may have very long period. As wave approach shallow water, wave heights increase and wavelength decreases. Consequently, wave steepness (H/L) increases. The waves become unstable when height is about eight tenths of the water depth and forms a