handling long hydraulic lines. The use of an electromechanical cable 

 appears desirable to avoid cable entanglement problems. Control for 

 the hydraulic motors and cylinders can be telemetered down the power 

 cable. For the power levels tentatively proposed the use of a sea- 

 floor source of electric power does not appear feasible. 



In the following sections, brief descriptions of conceptual designs 

 based upon each of the emplacement mechanisms are presented. The 

 relative advantages and disadvantages of each conceptual design are 

 discussed, and a semi-quantitative method is employed to compare the 

 designs and select the best system. 



Vibratory Driver Systems 



For vibratory driver systems, several designs are possible depend- 

 ing upon the specific type of vibrator utilized and upon the mode of 

 operation of the system. Two general types of vibrator are available: 

 eccentric-weight drivers and linear oscillators^. Although the devices 

 operate quite differently it was concluded that either could be used in 

 an underwater system, and that neither type offers any significant 

 advantage in meeting the operating requirements listed above. This 

 factor was thus eliminated from the conceptual design. However, it 

 should be noted that eccentric-weight devices have been developed to a 

 greater extent than linear oscillators, which gives the eccentric- 

 weight drivers a cost advantage. 



Three general modes of system operation were considered. In the 

 first mode all of the piles are lowered with the template, and a 

 separate vibrator is provided for each pile. Electric power would be 

 supplied from the surface and converted to hydraulic power at the sea- 

 floor. The control system would direct the power to one vibrator at a 

 time. At the end of driving, the vibrators, electrical and control 

 subsystem components would be detached and retrieved for reuse. 



In the second mode the system utilizes a single vibrator to drive 

 all piles and an indexing system to position the driver from one pile 

 to another. All piles are lowered with the template, as above. The 

 electrohydraulic power system is also essentially the same as the first 

 mode. The control system must control the indexing system as well as 

 the power to the vibrator. It would also be necessary to provide a 

 device for clamping the vibratory driver to the head of each pile, and 

 for detaching the driver at the end of each driving cycle. This device 

 must provide a rigid coupling of driver to pile for best efficiency of 

 the vibratory driver. 



In the third mode the piles are lowered with the template and a 

 single vibrator is handled on a separate line from the surface vessel. 

 The system must provide means for locating and positioning the driver 



