Special anchor designs are needed to overcome these deficiencies. 

 Key criteria for a deep ocean anchor are that it be capable of directly 

 embedding into the seafloor without being dragged and capable of 

 resisting uplift as well as lateral loads from all directions without 

 reducing its holding performance. Other desirable attributes are that 

 the anchor be lightweight, well configured for handling and lowering, 

 simple in operation, economical of materials and construction, self 

 controllable or controllable from the surface, and readily adaptable 

 to different appurtenances and connective gear. 



In addition to the anchor implement, improvements are needed with 

 respect to the connective gear and appurtenances plus the equipment 

 and techniques for handling and installing anchorages in deep water. 

 However, it is judicious first to proceed with improving the single 

 most important feature of a moor, the anchor. Direct embedment of 

 anchors may be achieved by free-fall impetus and/or applied power. 

 Some principal means of powering an anchor into the seafloor are jetting, 

 drilling, vibrating, and propelling with explosives. Considering 

 state-of-the-art of hardware, operational factors for control and 

 placement and cost factors, four anchor concepts have been investigated 

 at the Laboratory that incorporate in one form or another the free-fall, 

 jetting, explosive, and vibratory principles. In addition, a design 

 suitable for supporting bottom rest structures was explored. Substantial 

 knowledge and experience has been gained and a vibratory anchor concept 

 has approached a usable state. Further work on this concept is expected 

 to improve its operation and help define the limits of its capability. 



ANCHOR SYSTEMS REVIEW 



The "Free-Fall" Anchor 



Design Considerations . The "free-fall" concept considered in the 

 Laboratory anchor program is one that utilizes the "free-fall" principle 

 not only to lower the anchor rapidly and efficiently to the seafloor 

 but also to achieve embedment by the free-fall impetus. Results of 

 work with this concept were reported (Smith, 1966a). Pertinent facts 

 are presented here to place the "free-fall" anchor developments in 

 proper perspective relative to the further program. The prospects 

 of a "free-fall" anchor that would accomplish the functions envisioned 

 were intriguing. Though holding capacities would be limited to moderate 

 values, many urgent requirements for anchoring relatively small structures 

 could be satisfied. Quick, easy, more accurate placement of anchors 

 could be achieved and better holding power efficiency as measured by 

 holding power-to-weight ratio could be attained. Holding capacities 

 of 15,000-25,000 pounds were considered adequate values to meet these 

 requirements. 



