Fig. 14.13 DEEPSTAR 2000s 3-man Winslow ' life rati 



ing in sea state 6 and possibly higher. A 

 substantial number of the shallow-diving ve- 

 hicles have a conning tower which is an 

 integral part of the pressure hull and ex- 

 tends 1 or 2 feet above the waterline where it 

 is capped by a cover (Fig. 14.14). With these 

 vehicles, opening the hatch in any but a very 

 calm sea risks swamping. To avoid this, sev- 

 eral submersibles incorporate special fea- 

 tures to permit cabin air replenishment or 

 egress from the surfaced vehicle. 



Inflatable Hatch Trunk: 



In DS-4000, SP-350, SP-500 and SP- 

 3000 the hatch is below or just at the water- 

 line when surfaced; if it were opened the 

 pressure hull would flood. To avoid this the 

 designers have incorporated an inflatable 

 trunk or conning tower around the hatch 

 which, when inflated, affords a measure of 

 protection from the sea. In DS-4000 (Fig. 

 14.15) an inflatable, 39-inch-high conning 

 tower is installed around the periphery of 

 the hatch. An externally-mounted air cylin- 

 der is used to inflate the rubberized nylon 

 tower which is operated by turning a me- 

 chanical shaft within the pressure sphere. In 

 normal vehicle operations, the tower is 

 stored in a fiberglass trough. The storage 

 housing is topped by a fiberglass cover inte- 

 grated into the basic fairing and the cover 

 pops free from its spring-loaded catches as 

 inflation forces the tower upward. 



Inflatable Modules: 



The U.S. Navy's MAKAKAI has about 1.5 

 feet of freeboard at the hatch when surfaced. 

 Hence, operator entry and exit are normally 

 made with the vehicle on the support boat. 

 In the event of a need for emergency exit, a 

 system is incorporated to provide both free- 

 board and surfaced stability. This system 

 consists of four inflatable rubber cylinders 

 which are normally rolled and stowed in 

 containers attached to the vehicle's frame. 

 The cylinders are inflated from a 70-cubic- 

 foot scuba bottle by actuating a solenoid 

 valve. When inflated (Fig. 14.16), they pro- 

 vide an additional displacement of 55 cubic 

 feet, thereby raising the hatch about 4 feet 

 out of the water. The system also stabilizes 

 the boat if one or both battery pods are 

 released. Of the acrylic plastic-hulled sub- 



673 



