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 TB 55-1900-232-10
1-3.2.5 Chain Pendants and Bridles. The short length of chain used to increase the catenary as mentioned
in the above paragraph also serves another purpose: that of providing a rugged, chafing- resistant attachment
point for the hawser at the tow end. Chain, like other marine tension members, has evolved over the years.
The Boston Naval Shipyard led U.S Navy chain development and manufacture for many years. Two major
developments and manufacturing responsibilities at the Shipyard were die lock chain and the Navy detachable
link. With the deactivation of the Boston Naval Shipyard in 1972, this capability was lost to the Navy, although
similar products were commercially manufactured until the mid-1980s. See Appendix D for a complete
discussion of chain.
1-3.2.6 Spring. In towing, a spring absorbs shocks due to dynamic loading of the towing system. It is a rope
made of material exhibiting elastic behavior It is for this reason that, for the last 25 years, the ocean towing
industry has been interested in nylon line and, more recently, other synthetic fiber lines as well. Nylon replaced
manila in hawsers and spring pendants because of its superior elasticity and because, strength-for-strength, it
was smaller, lighter, and easier to handle. Nylon line has other beneficial properties, which include its
resistance to mildew and rotting, a serious problem in natural fiber lines. How- ever, nylon exhibited certain
disadvantages, including susceptibility to damage from ultraviolet light, loss of strength when wet and a
perplexing history of unexplained failures. Use of nylon in towing currently is restricted. Recently, other
synthetic materials have attracted increased interest. See Appendix C for more information on fiber lines
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