Appendix B 

 ANCHOR INSTALLATION AND RECOVERY METHODS 



TWO LINES «600 feet) 



This is probably the simplest shallow-water 

 approach for retrieving the launch vehicle after each 

 firing. As described in Figures B-1 and B-2, the 

 technique involves one hne to the gun assembly and 

 one to the fluke assembly. The latter line must be 

 firmly attached to the gun assembly above the figure- 

 eight flaked portion of the line and then released 

 upon firing. Line entanglement is prevented by main- 

 taining considerable distance between the two lines as 

 they are payed out. The practical limit for the 

 technique is 600 feet, even with a 200-to-300-foot 

 line separation. One method is to take the bitter end 

 of the anchor line in a small boat and apply moderate 

 lateral tension as the anchor system is lowered to the 

 seafloor. This approach may increase depth capabil- 

 ity. Another possibility arises from the guideline 

 experiments of Liu in Reference 8. In these experi- 

 ments, an object was lowered with just a few feet 

 between the lines to depths of 3,000 feet without 

 entanglement. Carefully controlled line tensions using 

 air tuggers was the key to the successful technique. 

 The complications of using the method to signifi- 

 cantly increase launching system retrieval depth 

 would have to be weighed carefully against the 

 increased time and expense involved in recovery. 



PISTON RETRIEVAL (<150 feet) 



For relatively shallow water depths, the capability 

 to retrieve the piston reduces per anchor cost by 

 $300 to $400, which is a significant portion of the 

 total cost of expendables. This retrieval method is 

 illustrated in Figure B-3. The anchor down-haul cable 

 (pendant) is connected directly to the keying plate; a 

 second line is attached to a pad welded on the piston 

 and coiled inside or on the launch vehicle. After 

 firing, the gun assembly is retrieved, and the line to 

 the piston, which is also connected to the gun 

 assembly is payed out. Once on deck the piston line is 

 placed on a capstan or winch, and the piston is pulled 

 free of the seafloor and to the surface for eventual 

 reuse. 



BUOY-LAUNCHED ANCHOR «600 feet) 



The U.S. Army MERDC [9] uses this method 

 with a catamaran hull for shallow-water installation 

 of their XM50 propellant-actuated anchor when 

 surface support is unavailable. Basically, the anchor is 

 placed in the catamaran, which is towed to the 

 anchor location. The anchor is lowered by winch on 

 the buoy to the seafloor for contact firing; the 

 catamaran buoyancy is then used to set the anchor 

 fluke. The gun assembly is winched to the catamaran, 

 and the catamaran is towed to shore for anchor refur- 

 bishment. In certain cases, to save time, the 

 catamaran can also be used as the mooring buoy. 

 Figure B-4 depicts the generalized scheme. 



To extend the maximum usable depth for this 

 method, a single lowering line, to prevent 

 entanglement, is required. An option for either 

 discarding or recovering the anchor gun assembly is 

 available. Methods for recovering the gun assembly in 

 deep water are discussed in some of the following 

 sections. 



GUN ASSEMBLY MESSENGER LINE «3,000 feet) 



The lowering line for the anchor system in this 

 technique. Figure B-5, is also the main anchor line. 

 Upon anchor firing, the gun assembly is released from 

 the anchor line. Simultaneously, a small line (large 

 enough to retrieve the gun assembly) is released and 

 pulled from a reel or bale by a buoy to the surface. 

 Either a rigid or inflatable buoy could be used in this 

 method. A lightweight, low-volume high-strength 

 Kevlar appears suitable for the retrieval line. 



ANCHOR MESSENGER LINE «3,000 feet) 



This technique could be patterned after one used 

 for the PACAN anchor [10] . In die PAGAN system 

 (Figure B-6) a braked cable drum with small diameter 

 wire is included with the gun assembly. This wire is 

 attached to a coupling mechanism at the bitter end of 



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