UNDERSEA TECHNOLOGY 79 



Another concept under consideration is that of the propellant- 

 imbedment anchor. This anchor is a self-contained device similar to a 

 large caliber gun consisting of a barrel, a recoil mechanism, and the projec- 

 tile, which is the anchor. Experimental observation of these devices under 

 test loading to depths of 6000 ft have demonstrated their potential for 

 deep water application; however, the tests have also pointed out limita- 

 tions in reliability and capacity. Currently a larger propellant-embedment 

 anchor rated at 50,000 pounds capacity is being investigated. The anchor, 

 developed by the U.S. Army Research and Development Laboratory for 

 use in coastal waters, is being modified by the Navy for use at greater 

 depths, with the target depth set for 6000 ft. 



To provide an anchor point in the sea floor that is totally fixed and 

 will support an applied load from any direction, the propellant-imbedment- 

 anchor concept was applied to an anchorage complex for bottom-mounted 

 structures. The design as produced is a tripod frame with articulated bear- 

 ing pads at the extremities and is referred to as the Padlock anchor. 

 Propellant-actuated imbedment anchors are mounted in each of the three 

 arms above the bearing pads. The anchors are driven into the sea floor 

 through openings in the pads. The other end of the cable that is attached 

 to the anchor is connected to a cable-rewind mechanism at the center. 

 The rewind mechanism pretensions the anchor lines after the anchors are 

 imbedded. 



The Padlock anchor has been demonstrated to be feasible and has func- 

 tioned satisfactorily in shallow water. This anchor can be used as a foun- 

 dation component when set down in a group of three or more. Three 

 Padlock anchors can be joined by a framework and can support a large 

 load of perhaps a few hundred tons. 



These methods for anchoring to the ocean floor can be roughly termed 

 static, in that the anchors firmly attach themselves to the sea floor and 

 from then on require no expenditure of energy to maintain their positions. 

 In contrast to this method is the dynamic positioning method, which has 

 been used successfully in positioning certain ships and barges. Dynamic 

 positioning uses propellers located advantageously such as bow thrusters 

 to position the ship precisely and to maintain this position on the open 

 ocean. 



During recent years, the Navy has installed several permanent ship moors 

 in depths as great as 6000 ft. From these moors has evolved a design tech- 

 nique suitable for holding large ships in a relatively fixed position against 

 wind, waves, and current. Six moors were designed and installed by the 



