The P3 pontoon has an inclined deck5'1 3/4" long and 7' wide. (See fig. 103.) The deck slopes from 4' 11 3/8"to3'8 1/4" high. The bottom is horizontal. All plating is 3/16" thick The sloping deck is fitted with five 1" square ribs 5/6" long, evenly spaced and secured by welding, with a covering of nonskid paint applied between the cleats. The P3 is used in conjunction with the P4 to form a gradually sloped ramp for causeway ends and ramp barge bows.

The P4 pontoon has a deck 5'1 3/4" long and 7' wide inclined at the same angle as that of the P3 pontoon. (See fig. 10-4.) The after end is 3'6" high; the forward end, 1'. The bottom is horizontal for 8" on the after end, then slopes upward. The deck, side, and back plates are 3/16" thick; the bottom, or bilge, plate is 3/8" thick. Five evenly spaced, 1" square ribs are welded to the sloped deck, and a coat of nonskid paint is applied between the cleats. Used in conjunction with the P3 pontoon, the P4 forms a continuous ramp for causeway ends and ramp barge bows.

Figure 10-3. - P3 sloped deck pontoon,

Figure 10-4. - P4 ramp-end pontoon.

P5 pontoons consist of P2 pontoons with quick-lock hinge connectors fixed to the bow. The P5M is a P5 with a male connector; the P5F is a P5 with a female connector. (See fig. 10-5.) P-series 3 x 15 pontoon causeways are connected end-to-end by alternate P5M and P5F pontoons; so are barge sections that are used as wharves where end-to-end connection is required. These pontoons are constructed by welding hinge connectors to P2 pontoons that are then assembled in male and female sequence, forming causeways of any required length. These pontoons are also used for enlarging or extending wharf structures. The center section of the P5F hinge is made from a section of extra strong pipe. When joined, these two parts resist the torsion, compression, and vertical shear forces in the joint.

Making end-to-end connections with P5M and P5F pontoons is not a difficult task (fig. 10-5). When the mating ends of two causeway or wharf sections are brought together, the male pipe connection is simply guided into the female and held in place by pad eyes and links. The resulting pipe joint then prevents vertical movement of either section. A short chain-locking device completes the connection and secures the links in the pad eyes. Each set of hinges is capable of withstanding 300,000 pounds of pull. Closure plates are welded on either side of each connection to bridge open spaces between pontoons.

A wide variety of structures-wharves, barges, causeways, and so on-can be assembled from pontoons. In the assembly of pontoon structures, the pontoons are first joined into strings and the strings are launched; the floating strings are then attached to each other. Structures of not over three strings in width can be entirely assembled on land and then launched as a unit. The number of pontoons in each string and the number of strings attached to each other depends upon the size and type of structure being assembled. The manner of assembly is similar in each case with variations depending largely on the intended use of the completed structure. The size of each pontoon structure is designed by indicating the number of strings in the assembly and the number of pontoons in each string, Thus a 3 x 15 causeway section is three strings wide and fifteen pontoons long. Pontoon gear is usuaIIy shipped with the parts required to complete a specific structure.

PONTOON ATTACHMENTS

Pontoon attachments, used in the basic assembly of pontoon structures, include assembly angles, bolts, nuts, keepers, assembly plates, and closures.