requirements for fitting around plates and lift pads. They also can be configured to provide access to assembly angles between structures for wrapping chains and wire rope during causeway beaching and LST side-carry operations. Formerly, five types of closures were needed to perform the necessary functions. These were identified as DC1 through DC5. The DC6 deck closure (fig. 10-14), with certain field alterations, was designed to fulfill all closure requirements and will replace the five closures entirely when stocks of these have been depleted.

The H22 and H23 closure plates are used for joining pontoons and for making bridge-to-wharf or barge-to-wharf connections. The H17AF and H17AM heavy-duty hinges are used to close the deck openings formed by the hinges between the pontoon sections. The closures (fig. 10-15), which are 20" wide and 24 1/4" long, are made from 1/2" steel plate and are used in combinations to fit over and enclose the heavy-duty hinges. Nonskid coating is applied on the top of the closures to prevent slippage. The H22 and H23 closures are not included in the heavy-duty hinge set. They are to be fabricated in the field as required.

BITTS AND CLEATS

Bitts and cleats are steel posts, or arms, to which lines are secured. Structures to be side-carried should have bitts and cleats, as well as all other deck fittings,

Figure 10-14. - DC6 deck closure.

Figure 10-15. - Closure plates H22 and H23.

bolted down on the launching angle side. A typical cleat is shown in figure 10-16. The B1 all-purpose bitt (fig. 10-17) consists of a single 4" diameter post that is 13" long with a 6" diameter cap welded to a base that has two drilled holes for A6B assembly bolts. A 1 1/2" diameter crossarm, 16 1/2" long, runs through the post approximately 10" above the deck. The B1 can be used on all structures requiring a single bitt and can be welded to the deck angles opposite the launching angle side.

The B4 bitt (fig. 10-18) is the same as the B1 bitt except for the base that has been designed for quick positioning in the CP1 chain plate.

Figure 10-16. - Cleat.

Figure 10-17. - B1 all-purpose bitt.

Figure 10-18. - B4 retractile bitt.