Thus, in-service forces tend to embed them deeper. In contrast, special 

 anchors such as the "free-fall" must attain embedment of their flukes 

 by an applied force opposite to that which they ultimately must resist 

 when in service. Thus, in-service forces tend to extract them. 

 Consequently, it is important that the flukes of the free-fall anchor 

 penetrate as deeply as possible into the seafloor during placement. 

 To accomplish this penetration, the anchor and flukes must present 

 a minimum resistance to the soil. Following embedment, it is essential 

 that the flukes change to a position offering maximum resistance to 

 movement through the soil. Further, they should change to this position 

 with the least possible vertical displacement because the deepest, 

 least disturbed material reached by the flukes with few exceptions will 

 afford greater resistance to in-service loads than the overlying sediments 

 the flukes have passed through. 



Description and Results . A free-fall anchor design within the 

 context of task goals was achieved. Prototype and model scale testing 

 were conducted. After minor modifications to the initial design, the 

 NCEL free-fall anchor. Figure 6, evolved. It is a steel construction 

 in the general shape of an arrow and consists of three basic components; 

 a fluke assembly at the arrow-tip end, a heavy steel shank in the 

 central portion, and a barrel shaped bale with protuding fins at the 

 trailing end. The design incorporated the coil payout cable system 

 and a unique fluke design to gain the maximum potential of the free-fall 

 anchor principle. 



As reported (Smith, 1966a) the free-fall anchor as a practical, 

 usable deep sea anchor that could be free-dropped and, by its own 

 impetus, embed into the seafloor and develop a holding capacity of 

 sufficient amount to warrant its use in place of dead weights was not 

 obtained. The primary reason was that the size and configuration of 

 the anchor necessary to accommodate the cable bale combined with the 

 size and shape of flukes necessary for reasonable holding power were 

 not compatible with attaining the velocity needed to obtain adequate 

 embedment. For example, it was determined that even with the maximum 

 theoretical velocity attainable by free-fall (about 35 fps) a holding 

 capacity to weight ratio of only 3 or 4 to 1 could be obtained. A 

 minimum ratio of 7-to-l is considered necessary for the free-fall 

 anchor to be feasible. 



Despite failure to achieve the idealized goal for a free-fall 

 anchor, significant contributions toward development of improved, direct 

 embedment deep sea anchors were realized. The cable payout system for 

 deploying anchors in the deep sea works , and has practical application 

 within certain operational, size, and depth limitations. Knowledge 

 and experience gained can be used to good advantage in utilizing this 

 system in deploying future deep sea anchors. More important is the 

 revolutionary fluke incorporated into the design of the free-fall 

 anchor. This fluke proved highly efficient and is adaptable to other 

 types of direct embedment anchors. A more detailed description of the 

 new fluke is given in the section dealing with the vibratory anchor. 



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