Prospective advantages of explosive anchors for deep water use 

 outweigh the disadvantages. However, work with them was suspended in 

 favor of the vibratory anchor design when it was conceived. The 

 vibratory anchor appeared to possess more favorable operational and 

 control characteristics. 



Pulse- jet Anchor Concept 



Background. The pulse- jet anchor concept came to attention during 

 the investigation of the explosive anchors. It became evident during 

 testing of the explosive anchors that a power action extending throughout 

 the embedment phase of anchor placement would be advantageous by more 

 readily accommodating the variable resistance to penetration offered 

 by seafloors comprised of hard and soft sediments. The pulse-jet 

 principle offered a potential that would achieve the goal of extending 

 the time during which power is applied to embed the anchor. The 

 concept was investigated under contract by Sea Space Systems, 

 Incorporated. The Contractor was to design and fabricate two experimental 

 models and conduct developmental testing. Then two prototype models 

 were to be delivered for Government testing. 



The concept proved to be not feasible and the contract was reduced 

 in scope to include a report on the effort (Lair, 1967). Salient facts 

 about the pulse- jet anchor are presented here to help cover all aspects 

 of the deep ocean anchor development program. 



Description. The pulse- jet anchor as envisaged is comprised of 

 two principal parts called a Mass Drag Reactor, Figure 13, and a 

 Ballistic Embedding Anchor, Figure 14. For application, the Ballistic 

 Embedding Anchor is meshed with the Mass Drag Reactor. The resulting 

 assembly is lowered to the seafloor. On contact, a propellent in the 

 Mass Drag Reactor gives the Ballistic Embedding Anchor an impetus to 

 embed at least its own length into the seafloor. To this point, the 

 principle is similar to that for other explosive anchors. The Ballistic 

 Embedding Anchor consists of three main components: a main structural 

 body, an inner inertial reciprocator which executes a short stroke with 

 respect to the structural body, and an innermost free-sliding valve 

 which executes a shorter stroke than the reciprocator and governs the 

 stroke of the latter. As it is expelled from the Mass Drag Reactor, 

 the anchor comes to contain a charge of expulsion gages that is trapped 

 and sealed into the anchor at about 20,000 psi. Beyond this point 

 the principle differs from that of other explosive anchors. This 

 charge of gas is then distributed by the valve to drive the reciprocator 

 up and down and ultimately is exhausted forward from the anchor nose 

 to break up the seafloor in front of the advancing anchor. The embedment 

 phase ceases when the gas pressure equals that of the ambient sea. 

 Then as load is applied to the anchor, it keys over to a position of 

 maximum resistance. 



21 



