•V 



as does weight handling. The upper limit for weight to be handled in water 

 by divers using a lift assist device vas considered to be about 600 pounds. 

 The probable mass of anything greater vould possibly cause the ievice/load 

 system to be too difficult to handle. 



The oinlciuis size of the device is Halted by the arrangement and cube 

 of components required to provide the desired buoyancy at a 1 ,000-foot-depth' 

 and to house the messenger line and male prod. 



In consideration of the economic aspects, compressed gas was chosen to 

 provide buoyancy for the prototype unit. A second generation design could 

 Incorporate a method such as the decomposition of hydrazine and any such 

 future development could utilize the spaces occupied by the compressed gas 

 bottles in the prototype. Either method eliminates expending expensive 

 lead or steel shot to provide variable buoyancy. An inflatable/collapsible-bag 

 buoyancy chamber provided with a zlppered closure, vertically oriented in 

 its sidewall, serves as the buoyancy chamber. The collapsible buoyancy-bag, 

 when properly placed and inflated, will also serve as a soft nose or 

 bumper to reduce the hazards of its ascending beneath equipment or personnel. 



The rate of upward acceleration of the device is nainly dependent 

 upon its positive buoyancy and drag factors. The cessenger line does 

 not contribute significantly to the drag factors for the H-W system 

 because the line is payed out without restraint. In a new design, the line 

 could be utilized to slow the rate of ascent and absorb some of the energy. 

 One method would use the line to rotate a reel as the line payed out. A brake 

 automatically applied to the reel would convert some of the energy. The 

 brake could be of the water-brake type. Other design features of the reel 

 and the method of attaching the messenger line to it could provide a 

 means for recovery and reuse of the line. 



To achieve approxtnate neutral buoyancy, the new design could 

 utilize either low density materials or one-atmosphere voids to offset 

 use of high density materials where required. 



Figure 3 illustrates a conceptual arrangement in which each of the 

 above items has been considered. 



DESIGN OF CONCEPT 



The design as developed by CEL utilizes two laajor subassemblies.'^ 

 Design of the first subassembly began b> finding package dt=ensions 

 for the compressed gas required for a 6C0-pound lift capability at a 

 depth of iOO feet. Design parameters included vertical orientation of 

 the device. The most readily available off-the-shelf source of this 

 compressed gas packaging is the common scuba bottle. One *72* scuba bottle 

 will provide approximately 320 pounds of buoyant lift at a 400-foot depth. 

 Although this capacity does not provide the full 600-pound lift capability, 



Naval Civil Engineering drawings 71-40-1F through 4F 

 are available on request. 



