3. The equipment and the floor were to be attached to the preten- 

 sioned tie rods (Figure 12). For such an arrangement, the tie-rod springs 

 would be located near the top hatch so that the portion of the tie rods to 

 which the floor and equipment were attached would not experience any 

 displacement relative to the bottom metal plate to which hydraulic tubing 

 and electrical leads were attached. The disadvantage of this arrangement 

 lies primarily in the difficulty of packaging equipment with respect to the 

 tie rods. Furthermore, problems would be encountered in the removal of 

 equipment for maintenance and modification as in many cases the tie rods 

 would have to pass through the equipment in order to exert proper vertical 

 and lateral restraint. 



4. The equipment was to be bolted to the floor, which in turn would 

 be bolted to the bottom metal plate insert (Figure 13). Since the diameter 

 of the floor is larger than that of the bottom metal plate, it cannot rest 

 directly on the bottom plate but must be held some distance above the plate. 

 To avoid having the floor rest on the compliant acrylic plastic hull while it is 

 restrained by bolts to the rigid bottom metal plate, a spacer has been provided 

 that keeps the floor a fixed distance above the bottom steel plates. A small 

 clearance is provided between the edge of the floor and the inner wall of the 

 capsule to allow for the shrinkage of the sphere without imposition of restraint 

 on the sphere and compressive loading on the floor. Since all the equipment, 

 occupants, and the floor rest on top of the bottom metal plate, approximately 

 a 1 ,000-pound force acts upon it. Whether this downward-acting force gener- 

 ates tensile stresses across the bonded joints between individual pentagons 

 depends on the method used for attaching the capsule to the NEMO exostructure 

 and whether the capsule rests on deck, is being lifted, floats on ocean surface, 



or is submerged at its operational depth. When pretensioned tie rods are used 

 on the interior of the capsule, and the bottom metal plate is rigidly attached to 

 the ballast pod, no tensile stresses can be generated by the weight of the equip- 

 ment in the interior of the capsule regardless of the stage of launch or retrieval 

 operations. When the capsule is held in place by the external cage with sliding 

 pin joints, tensile stresses are generated in the bonded joints when the capsule 

 floats on the ocean surface. At that time, the bottom metal plate is not being 

 supported by the external cage since the capsule has lifted off its bottom sup- 

 port in the cage and is pushing against its top seat in the cage. Furthermore, 

 the hydrostatic pressure acting on the bottom pentagon from outside is not 

 high enough to equal the downward force exerted from inside on the plate 

 by the weight of equipment located in the capsule. Thus, the resultant force 

 that is equal to the difference between (1) the sum of the weights of bottom 

 metal plate, polar pentagon, and internal equipment and (2) the upward- 

 acting hydrostatic pressure on the bottom pentagon generates tensile stresses 



21 



