SALVAGE TESTS 389 



negative, all planned buoyancy should be installed* The tendency of divers to want to quit once 

 the body has floated should be resisted. The Sealab II divers had not been so instructed. Pos- 

 sibly had the foam been of better quality, we would not have learned this rudimentary point so 

 quickly. 



The several oil drums were foamed successfully and without incident. All floated to their 

 tethers. The fact that they did not sink again, like the aircraft, is indicative that they were 

 "over-foamed." The small size of the drum required that the diver foam for only about a min- 

 ute. It was almost impossible to "under-foam." Also the drums, being totally enclosed except 

 on their bottom, presented very little wetting surface for water absorption. 



It has been mentioned that the foam was of poor quality. As the foam chemicals were ap- 

 plied by triggering the gun, the exothermic reaction took place, but the freon gas, used as the 

 frothing agent, was not effective. The partial pressure of the freon gas at the depth and tem- 

 perature of application was too close to ambient depth pressure. The gas did not consistently 

 froth. The foam was too dense and had poor shear characteristics. It appeared that the initial 

 shot of each application did not foam at all, until the exothermic reaction got "heated up." This 

 initial amount of unfrothed foam material quickly solidified as a ceramic-like mass. In at least 

 one instance, it covered the divers' Mark VI breathing apparatus, and completely fouled their 

 breathing bags and exhaust valves. The danger is obvious. 



So far as the Sealab II FIS demonstration is concerned, the project is considered to have 

 been quite successful. It was clearly demonstrated that divers, at a dept of 205 ft, could handle 

 the foaming equipment. It was also demonstrated that a diver-topside evolution could be per- 

 formed, even without communications. The salvage engineering lessons learned were particu- 

 larly worthwhile. The foam itself was, without doubt, disappointing. In fact, the foam was an 

 order of magnitude less satisfactory than had been obtained during preliminary deep tests held 

 in San Francisco Bay. 



VELOCITY POWER TOOLS 



Velocity power tools which utilize the energy from an ammunition-type cartridge to drive 

 threaded solid and hollow studs into and through steel plates have been used by divers since the 

 late 1930's. However, because of several accidents during World War II and the unavailability 

 of parts, these tools fell into disuse in the Navy. Prior to Sealab II, few active divers had any 

 experience or appreciation for the utility of these tools. The purpose of the tests covered here 

 was twofold: (a) to demonstrate the utility of the tools as applied to scuba divers in 200 ft of 

 water, and (b) to demonstrate an attachment padeye concept which might be used in submarine 

 salvage. 



The single-stud driver (Fig. 146) was an improved experimental model developed by the 

 Mine Safety Appliance Company of Pittsburgh, Pennsylvania, under contract to the Naval Ord- 

 nance Laboratory, White Oak, Maryland. The wire-rope cable cutter (Fig. 146) was an older 

 and proven design. The improvements in the single-stud driver in general provided for pene- 

 tration into various thicknesses of HY-80 steel plate. Other improvements enhanced diver 

 operability and safety by better containment of the explosive gas energy. This last improve- 

 ment reduced the shock on divers to negligible proportions. However, the single-stud driver 

 still must be fired with the head of the diver held out of the line of sight, to prevent shock load- 

 ing on the eardrums (Fig. 148). One aquanaut learned this in a painful trial shot, fired in a 

 shallow pool prior to Sealab II. The eight-stud lifting pad array was the prototype of a new 

 design, prepared under contract to NOL. 



All tool performance was satisfactory, with the exception of the cable cutter. The latter 

 was never successfully fired because of a defective "o" ring seal. The other prototype devel- 

 opment models performed well with only three duds out of 15 shots attempted. 



*The on-going BuShips/ Murphy-Pacific contract addresses this engineering problem. The sal- 

 vage engineer must know how miuch water absorption— both as to rate and quantity (lost buoy- 

 ancy) —to allow for. 



