INTRODUCTION 



BACKGROUND 



This report describes the development of the Civil 

 Engineering Laboratory's (CEL) 20K propellant- 

 actuated anchor (Deep-Water Anchor).* The project 

 was sponsored by the Naval Facilities Engineering 

 Command under the Naval Materiel Command's Deep 

 Ocean Technology program. The anchor was designed 

 to develop a minimum long-term holding capacity of 

 20,000 pounds in seafloors from soft clay to compe- 

 tent rock and to be operable in water depths from 50 

 to 20,000 feet. The results of the testing program 

 used to define the anchor's performance in a variety 

 of seafloor materials and in a range of water depths to 

 20,000 feet are given along with alternative installa- 

 tion and recovery schemes for the anchor. 



A detailed study of existing and conceptualized 

 anchors was undertaken to determine the most 

 suitable and widely applicable anchor for deep-water 

 operations. It was impractical to find an anchor that 

 would efficiently satisfy every application, but it 

 appeared that the propellant-actuated anchor offered 

 the widest range of applications. Of particular signifi- 

 cance were the propellant-actuated anchor's adapt- 

 ability to variable seafloor conditions and its high 

 anchoring efficiency. 



The ordnance system for the 20K anchor was 

 designed for CEL by the Naval Ordnance Station, 

 Indian Head, Maryland, and the anchor safe-and-arm 

 device was designed by the Naval Underwater 

 Systems Center, Newport, Rhode Island. The 

 remainder of the anchor system wa:s designed and 

 fabricated at CEL. Figure 1 is a view of the CEL 20K 

 anchor as it is about to be placed over the bow of a 

 Navy warping tug. 



The propellant-actuated anchor concept advanced 

 to the hardware st^e in 1959. Since that time several 

 propellant-actuated anchors have been developed by 

 both government agencies and private industry.** 

 Initial problems concei'ning structural and mechanical 

 aspects have largely been overcome; anchor reliabil- 

 ity, efficiency, safety, and simplicity have been 

 advanced to the point where this anchor can be 

 considered a viable alternative to conventional 

 anchors. 



Standard drag anchors behave poorly in rock, 

 coral, cemented, or very dense seafloors; holding 

 capacities are erratic or nonexistent. Anchor flukes 

 will not key into any of these seafloors. Capacity is 

 developed only through minimal friction or possible 

 snagging on a rock outcrop. In contrast, the 

 propellant-actuated anchor functions best in coral, 

 cemented or very dense seafloors. Data on 

 performance in rock are minimal, but results to date 

 indicate that large capacities are possible. 



In well-used harbors, channels, or any other 

 confined area it can be impractical to lay the long 

 scopes of chain or line on the seafloor required for 

 standard drag anchors. These mooring legs can be 

 disturbed by temporary ships' anchors and can 

 effectively reduce ship operating area because the 

 mooring legs rise close to the surface when in use. To 

 avoid this, large clumps are normally attached to each 

 leg to reduce chain scope, thereby resulting in a more 

 difficult installation. Line scope is considerably 

 reduced with propellant-actuated anchors, which can 

 minimize the difficulties hsted above. 



' CEL now has three propellant-actuated anchore; to simplify their reference, theii 

 names are designated simply by their nominal long-term capacity in a soft 

 seafloor sediment. 



' See Reference 1 for more detail on these anchors. 



