FIGURE 2-31. Multi-Sheave Traction Winch.
(Text continued from page 2-38)
2-5.8.4 Towing Hooks. Towing hooks rarely are seen in the United States, but may be encountered in foreign ports and
on foreign, especially European, tugs. They are heavy steel hooks mounted on vertical pins, which allow them to swing.
Each hook is shock-mounted by use of a heavy compression spring and fitted with a quick-release device which trips the
hook, in much the same way as a chain stopper.
The compression spring provides a small amount of dynamic load relief for the towline system.
2-5.8.5 Bitts. A bitt is a strong post used for belaying, fastening, and working ropes, hawsers, mooring lines, etc. Bitts
usually appear in pairs and are named according to their use. See Figure 2-32.. They generally are not suited for towing
operations. The term "bollard" occasionally is applied to a bitt, but more commonly is applied to a device on a pier for
securing mooring lines. Bitts on U.S. Navy ships are designed to withstand a load equal to at least three times the
breaking strength of the line for which they were designed. See Paragraph 5-6.2 for design strengths of U.S. Navy bitts.
2-5.8.6 H-Bitts. Towing or H-bitts are heavy steel castings or weldments secured to the ship's structure and are generally
located near the tug's pivot point where they provide the hard point that sustains the athwartship loads imposed by the
towline when it sweeps the fantail. In tugs fitted with towing machines, the H-bitts prevent transverse strain on the level
wind mechanism and are used to stop off the tow wire when necessary. On the ARS 50, the function of the H-bitts is
integrated into the deckhouse structure.
2-5.9 HANDLING SYSTEM. The towing machines, winches and bitts discussed in the preceding paragraphs provide
some line han-