are amenable, by virtue of their small size, to 

 options other than the deep sea. Test tanks 

 offer the advantage of being far less expen- 

 sive and troublesome than open-ocean test- 

 ing; pressures can be better controlled, and 

 the test can be monitored more precisely. A 

 great advantage lies in the fact that the 

 pressure hull alone may be tested prior to 

 completion of the entire vehicle. Invariably, 

 when the vehicle must be tested as an oper- 

 ating unit, failure of operational compo- 

 nents, such as motors, depth gages, sonars, 

 etc., or inclement weather, results in delayed 

 test programs. In a test tank the vehicle may 

 be tested component-by-component, then as- 

 sembled and tested in its entirety. In the 

 event of hull failure, an obvious advantage 

 with such testing is that no personnel are 

 required in the vehicle. Another advantage 

 resides in the speed with which the pressure 

 may be relieved or the tank emptied of 



water. If, for example, an electrical penetra- 

 tor failed and water began entering the hull, 

 the test tank could be emptied in a few 

 minutes. 



While unmanned open-sea tests on a tether 

 may be as conclusive as tank tests, they 

 include the risk that the object being tested 

 may be lost. As previously noted, both SP- 

 350 and SP-3000 pressure hulls were lost 

 when the tethers gave way. 



PRESSURE TEST FACILITIES 



According to reference (29), at least 23 test 

 tanks in the U.S. are sufficiently large to 

 accommodate submersible pressure hulls of 

 5-ft diameter and greater (Table 5.6). With 

 the advent of the Ocean Pressure Labora- 

 tory at the Annapolis, Maryland-based Na- 

 val Ship Research and Development Center, 

 whole vehicles such as DEEPSTAR 2000 

 (and larger) may be tested in their entirety. 



Fig. 5-22 (a) DEEPSTAR 2000 prepares to enter the US- Naval Ship Research and Development Center s 12.000 psi pressure tank (US Navy) 



270 



