CHAPTER 10 PONTOONS

When the United States entered World War II, our Navy was faced for the first time with the problem of landing and supplying large forces in areas where traditional harbor facilities were controlled by the enemy. Navy Lightered (N.L.) pontoons were developed in 1942 to meet this difficult situation. They were designed for erection by naval personnel and shipment aboard Navy vessels. These pontoons pro-veal to be an invaluable asset and were used extensively in operations during World War II, the Korean conflict, and again in Vietnam.

P-SERIES PONTOONS

P-series pontoons were used throughout the Republic of Vietnam in combat conditions. Although originally designed to meet the requirements of the Advanced Base Functional Component (ABFC) System, they have been used successfully in many other fields due to their inherent versatility and ease of erection. Large structures are easily and quickly disassembled then made into smaller structures, and then the smaller structures can be quickly and easily reassembled into larger structures. The light draft, structural strength, mobility, and adaptability of pontoon structures made them extremely useful for shallow water passage and tactical deployment in the Mekong Delta. They allowed movement of heavy weapons and shifting of firepower throughout otherwise remote areas. Many structures not discussed in this manual, such as armored barges, helicopter pads, mortar barges, and barracks barges, were constructed in the field for use in special situations throughout the waterways of South Vietnam.

TYPES OF P-SERIES PONTOONS

Five basic types of P-series pontoons are in use today, designated Pl, P2, P3, P4, and P5. These pontoons are specially designed, internally reinforced, welded steel cubes. They are tested to withstand an internal pressure of 20 pounds per square inch (psi). All pontoons have plain deck plates covered with a nonskid coating, and all are, fitted with a 2" plugged hole for air, drain, or siphon connections at the top and bottom of one of the end plates.

The P1 pontoon is cubicle in shape. (See fig. 10-1.) The deck of the P1 is 5'3/8" x 7', and the sides are 5'3/8" high. The side, end, deck, and bottom plating is 3/16" thick. The P1 is the most common and widely used pontoon in the P-series. Its usage is required in every structure of the pontoon system.

The P2 pontoon has the same depth (5'3/8") as the PI, but it has a 7' square deck and a straight-line sloping bow. (See fig. 10-2.) The side, end, and deck plates are 3/16" thick. The sloping bow plate is 3/8" thick. P2 pontoons are used on the bow and stern of various pontoon structures.

Figure 10-1.-P1 pontoon.

Figure 10-2.-P2 straight-line sloping bow pontoon.