The support guidance frame is a tubular tripod construction that 

 contains the battery power pack and orients and guides the fluke- shaft 

 during the embedment phase of operation. Guidance is provided by a 

 sleeve at the peak of the tripod, 6 feet off the seafloor. The tripod 

 has 3-foot diameter circular bearing pads welded to the end of each 

 leg to form an equilateral triangular base. The power pack batteries 

 are contained in three oil-filled pressure-compensated steel boxes 

 mounted in a rack that is fixed to the tripod 3 feet off the seafloor. 

 The battery boxes are interconnected by electrical leads to provide 

 240-volt, 30-ampere service to the vibrator unit via a cable. 



Appurtenant Instruments 



Instrumentation permitting remote sensing of the attitude of the 

 vibratory anchor when it rests on the seafloor and its penetration is 

 important. The anchor must remain upright prior to and during the 

 placement process. Also, the anchor capacity is highly dependent upon 

 the embedment achieved. The confirmation of embedment and knowledge 

 of the amount of penetration is necessary to predict the performance 

 of the anchor. The need for developing an attitude sensor was emphasized 

 during tests of the vibratory anchor in deep water. On some occasions, 

 the anchor overturned and the tests were unsuccessful. 



A displacement monitoring system and an attitude sensor were 

 developed during testing of the vibratory anchor. The displacement 

 monitoring system. Figure 21, is comprised of a spring-loaded wire 

 take-up mechanism, a rotating potentiometer, and a pinger. The wire 

 is stretched between the anchor vibratory unit and the take-up mechanism 

 which is mounted on the support guidance frame. In action, the anchor 

 is displaced relative to the support guidance frame. The wire is pulled 

 into the device by the spring loaded take-up mechanism and rotates 

 the potentiometer. The potentiometer is in an electrical circuit with 

 the pinger so the anchor's movement changes the ping rate. The ping 

 rate is detected with a hydrophone, recorded and later translated 

 into terms defining the linear displacement of the anchor fluke. 



The first displacement monitoring system was accurate to within 

 6 inches of displacement, which is sufficient to confirm embedment. 

 However, data for analytical studies used in efforts to optimize the 

 fluke size-depth relationship require more precise breakout displacement 

 measurements. Also, because loads applied during field testing are of 

 a transient nature, it was desirable to measure to within at least 

 1 inch the amount of displacements caused by transient loads. The 

 necessary increase in displacement sensitivity was accomplished by 

 changing the resistive range of the potentiometer. With this change, 

 the device measures displacements accurately to within about 2 inches 

 when the fluke is near the water seafloor interface and about 1/2 inch 

 when the fluke is fully embedded. The variation in accuracy is due to 

 the difference in the ping frequency that transmits the displacement 

 information. The instrumentation is designed in such a manner the ping 

 rate is faster and thus more accurate when the fluke is in the more 

 critical zone of embedment. 



35 



