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