get— transponder 



digital tape 



data conditioning recordei 



equipment 



Figure 22. In-situ long-term settlement test device— LOBSTER. 



The footing with attached instrumentation and the reference system 

 will be installed on the seafloor in water depths to 6,000 feet with the 

 DOTIPOS. Once the installation procedure is completed and the DOTIPOS 

 removed, the LOBSTER continues its mission for a preselected duration of 

 up to 1 year. 



At the end of the preselected duration of the test or upon special 

 acoustic command, the instrumentation capsules with attached relocation 

 and recovery aids are released from the footing and brought to the surface 

 by the floatation system. The digital tapes are then removed and the data 

 reduced and analyzed. An example of the type of information to be obtained 

 with this device is shown in Figure 23, which represents the results of a 

 shallow-water system checkout in Mugu Lagoon. The instrumentation and 

 recovery system, after overhaul and checkout, is fitted with another expend- 

 able concrete footing and reference system for installation in another site. 



Data obtained from the deployment of a LOBSTER at the site of a 

 proposed structure would be used in the design of the prototype foundation. 

 Extrapolations may be made from the observed performance of the LOBSTER 

 footing to predict the performance of the larger prototype foundation. 



36 



