spring accumulator bottles 



CZ>n 



[Eti 



spring 

 cylinder 



cz> 



CI> 



C3 



;iiti 



'JS^ 



33 



fA 



4,500 psi 



^ ^ BU 



a 



3=^ ci> 



^lIIM 



(11)C r-r-TT—i ^ 



HjEM 



4EW 



to gas transfer 



Figure 16. Spring system schematic. 



Comparison of these resonant periods with the 

 expected 2 to 12-second range of ship-motion periods 

 indicated that the system did not meet the design 

 objective of a natural resonance period much greater 

 than the ship-motion periods. A redesign of the spring 

 system doubled the spring accumulator volume. When 

 the system was retested with the large accumulator 

 and the 63,250-pound boom-tip load, the resonant 

 period was about 20 seconds, thus satisfactory for the 

 ship motions of interest. System damping was near 

 critical or possibly overdamped. 



Sea Tests 



All at-sea testing was conducted with the MCLS 

 mounted on the fantail of the MV GEAR (ARS 34) 

 (Figures 20 and 21). The at-sea test program con- 

 sisted of two series of tests, the first in September 

 and October of 1972 and the second during October 

 and November 1973. Test instrumentation covered 

 system performance topside and at the payload in 



both real time and recorded data. Details of the test 

 instrumentation system are included as the Appen- 

 dix. 



Two different payloads were used during the 

 testing program. The light payload (Figure 22) was 

 selected to give an in-water weight near the 

 10,000-pound minimum the MCLS was expected to 

 be able to handle. The heavy payload (Figure 23) had 

 an in-water weight of 40,000 pounds, the maximum 

 design capability of the MCLS. 



The planned test sequence throughout both test 

 series was to launch the payload being used, shift into 

 soft mode, lower it to depth, hold it at that depth for 

 15 minutes, lift it back to the surface, shift into hard 

 mode, and recover. Planned test depths started at 

 1,000 feet and lowered incrementally to 6,000 feet. 

 Additional holds were used at intermediate depths on 

 the 1,000-foot tests to gain additional data. 



15 



