Shore-to-shore operations use Army landing craft, amphibians, and LACV-30s to transfer cargo from one beach terminal to another along the same coastline. Water transport units may be called on to support combat forces conducting shore-to-shore assaults. They may also be requested to ferry cargo across or along rivers and between islands in routine resupply operations. Except for the fact that shipping is not involved, the operational techniques for water transport units in logistical and tactical shore-to- shore operations are identical to those described in Chapters 4 and 5. However, because of the nature of the terrain and the differences in control requirements, some basic planning considerations for shore-to- shore operations and particularly for river crossings are covered in this chapter.
During tactical shore-to-shore operations, the water transport unit commander does not select the final landing site. However, he does advise the tactical commander of the requirements for specific areas and indicates any conditions that would adversely affect the operational efficiency of the unit.
In shore-to-shore operations, there is normally sufficient time to prepare at the site to ensure mission success. In general, the site selection factors described in Chapter 3 must be considered when evaluating areas for shore-to-shore operations. Another factor to consider for river crossing operations is the location of crossing sites. Crossing sites must be located downstream from bridge sites to reduce the chance of disabled craft and floating debris damaging bridges.
Control points normally required for lighterage units in shore-to-shore operations are--
- Lighter control center.
- Loading area control point.
- Near-shore beach control point.
- Far-shore beach control point.
- Discharge control point.
These points operate in the same manner and fulfill the same functions described in Chapter 3. However, the loading area control point replaces the shipboard control point and a beach control point will be added on the far shore. In some cases, it may be expedient to move the lighter control center closer to the waterline and to eliminate the beach control point on the near shore.
The commander of the supported unit must consult the commander of the water transport company before designating assembly areas to be used in a shore-to-shore operation. Desirable characteristics of an assembly area include-
- Location as near as practicable to the crossing
- Easy entrance from the rear and good exits to
the crossing site.
- Sufficient space to permit dispersion of lighters
and to provide an adequate loading area.
- Defiladed so that the enemy cannot observe assembly
- Terrain firm enough to permit amphibians to pass
without using excessive power and its accompanying noise.
- Located as near as practicable to a safe harbor or inlet to protect the watercraft in a storm.
Planning for river crossings requires careful consideration of the characteristics of the body of water to be crossed. Each bank should have a 40 percent or less slope; that is, 40 or less feet of rise for each 100 feet of forward horizontal distance. The slope should gradually drop off at the water's edge. During operations, amphibians should use multiple routes into and out of the water to avoid forming deep ruts that would cause the craft to belly down. Earth-moving equipment may be used to decrease the slope of high banks and to level off entrances and exits.
Also consider the type and consistency of the soil at the crossing sites. Avoid marshy, swampy areas and soils with a clay base. When no hard-packed sand entrances and exits are available in the operational area, pierced steel planking, brush, and netting may be used to increase traction. Earth-moving equipment may be used to improve the trafficability of the entrance and exit routes at the crossing site.
Ideal conditions for a crossing site are a sandy shoreline with a gradual slope; clear, deep water; and a clear river bottom. However, these conditions are not often encountered in the field. Mud, the most difficult terrain to cross in an amphibian, is the type of soil usually found in and around rivers. Shallow rivers with soft bottoms are particularly difficult for these craft. If the river is too shallow to float an amphibian, its wheels will sink into the muddy bottom immobilizing the craft and increasing the danger of capsizing in swift currents. A shallow river with a bottom of large rocks presents similar problems for amphibians. Using underwater bridges constructed of sandbags can sometimes remedy these conditions.
Operation in rivers with swift currents (more than 4 mph) requires highly skilled, experienced operators. When exceptionally swift currents are encountered, it may be possible to rig a cable from one bank to another to assist craft in crossing. If this cannot be done, amphibians should back into the stream so that the rudder and propeller enter the water first. This approach gives the operator maximum control of the craft. It also causes the stern to float first so that it swings around and heads the bow into the current as the craft becomes waterborne.
It is unlikely that obstacles will be encountered in the center of the river, but conventional antitank, antipersonnel, chemical, and antiamphibious mines may be laid below the high waterline. Early reconnaissance by the tactical unit should locate mine fields in the area of operations so they can be removed or avoided during crossing. Water transport unit personnel must be trained to look out for mines and to mark and report their location. Naval mines probably will not be encountered in river crossing operations unless the river is deep enough for navigation by seagoing vessels. However, crew members must be alert for floating mines used to destroy bridges.
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