*v 



the handles and rlsk-s being dra^gi-'d to t.-^e surfnce. Occasi<.>aally , the ballast 

 shot bccoaefs lodged around the nested prod, causing i; to bind and preventing 

 disengage=«ent. 



7. All ballast shot reinaining in the char.ber wbra the prod is 

 disen<;aged to permit the device to ascend is duraped through the prod 

 housing. The costly lost shot is not retrieved. 



8. The size and weight of the device necessitates the use of materials 

 handling equipment for handling it aboard ship or placing and retrieving it 

 over the side. 



9. Econonic factors other than the high costs of aessenger line and 

 ballast shot include: (1) ballast shot is a high pilferage risk itea, 



(2) the device in its storage container and the ballast shot and messenger 

 lines utiliz'? valuable and limited space aboard ship, and H) the 'specialty 

 Ites' nature of the device linits ^ts usefulness. CThcugh variable buoyancy 

 diver lift assist devices, too, are specialty items--, rhey have won Navy 

 acceptance as valuable tool.>.) 



APPROACH TO DESIGN OF A NEV DEVICE 



Because the principles of the Kunley-Vii schhoeter device and the variable 

 lift assist devices vcre sound, it vas recorjnended tb-at a new device 

 incorporating the best features of both be developed for the Navy's 

 salvage forces. The new approach was to develop a diver's assist device 

 incorporating buoyancy variability, inf latability , messenger capability, 

 and reliability. It was to be econoaical, safe, and siniple. In approaching 

 the problera the factors which might linit use of the end iten were 

 established, and the concept was then developed wltiiiri the^^e constraints. 



Divers and support personnel aboard surface craft are expected to 

 handle the device with a ninimum of ii^terials handlir.5 support equijicent. 

 Therefore, mininum practicable dinensicns -inJ weight -<-ere required for the 

 device. These requirements were consistent with the rtquire::ent that the 

 device occupy a raininun of storage s;:ace. Based upon a ninixua-sized diving 

 tean of three nen, a drv weight liait of .ipproxicatel;.- 300 pounds was sot 

 for the device. 



Working depth capability of Na'/-- divers is currently liniteJ, Dut 

 cotrciercial working depths have recently been dramatically extended. These 

 new depths are considered pertinent to the design paraneuers lor tlit- new 

 device. An extended depth capability is also desirable to provide 

 conpatibility with capabilities of s::;a.ll canned subcersib^es. A reasonable 

 maxirun depth capability, consistent with prlnary use by divers, is 

 considered to be 1,000 feet for the foreseeable future. Inclusion 

 of cessenger line for 1 ,000-foot-depth operations wa^ nade a requirement. 



Divers are limited in v/ork capability by -nany factors. Endurance is 

 directly related to effort expended. T!ie sail area of an or^ject handled 

 by divers underwater is acted upon by currents and afTects diver endurance 



