WET SUITS 301 



uncertainty. However, several aquanauts had the opportunity of concentrating on their thermal 

 comfort and gave detailed evaluations. 



The heat-power distribution was evidently close to ideal. No subject complained of signi- 

 ficant unequal heating. Most subjects agreed that the power distribution was adequate. 



There was some hot-spotting in the boots and mitts, and only one man reported a hot spot 

 at the lower rear part of his neck. Hot- spotting in the boots occurred in the sole area and was 

 aggravated whenever the diver's weight caused pressure on his soles. This problem can be 

 corrected by heating only the upper parts of the foot. Hot-spotting in the mitts occurred on the 

 knuckles, where the contact pressure with the mitt is maximized by flexing the fingers. Lower- 

 ing of local wire temperatures by incorporating more wire may solve this problem. 



Snug-fitting heated wet suits will require careful fitting to prevent hot areas due to the 

 pressure of the suit against the skin. 



Power Source and Control 



There were no serious problems with the ac power source in Sealab n. The negatively 

 buoyant electrical umbilical cable had to be pulled along the bottom whereas the positively 

 buoyant Arawak hoses floated overhead. The two should have been mated together. But the 

 electric cable was fed out of the Sealab n hatch, while the Arawak hose passed through a bulk- 

 head. A systems approach in future programs should eliminate nuisance problems of this type. 

 One subject reported that his cable became disconnected from his power-control box. A safety 

 lock will prevent this from happening in the future. 



The silver-zinc battery pack was too bulky. A question exists as to whether or not it is safe 

 when worn with the Mark VI. Some subjects feel that it is safe; some do not. The battery could 

 have been one-third the size for Sealab 11. A one-kilowatt-hour battery to provide three hours 

 of heat at full power was specified in the contract. However, the gas duration of the Mark VI 

 was only about 50 minutes. 



The power-control boxes maintained watertight integrity and operated well electrically. 

 The uppermost switch control (power range) was easily knocked out of position. A more posi- 

 tive switching arrangement will have to be designed. 



Miscellaneous 



Only one subject reported skin irritation. All others reported none. The afflicted diver 

 stated that his skin was discolored prior to donning the suit and that he wore the suit for more 

 than 12 hours. His skin may have been abraded by the wet nylon suit lining. 



All subjects found it difficult to don their fins over the heated boots. It will be necessary 

 to wear a larger fin over the heated boots unless the boot is made thinner. However, this would 

 reduce its insulating property and require more electrical heating. Additional heating will 

 mean less battery time, or larger batteries. 



On the positive side, at least three subjects wore the suits without using the supplemental 

 heat power. They claimed that the suits did not suffer from the pressure effect as did their 

 sponge neoprene suits. The suits achieved normal dimensions immediately after opening the 

 gas valves in Sealab U. Neoprene suits, on the other hand, were severely distorted for the 

 first few days, until the habitat atmosphere gases permeated the closed cells. Upon ascent to 

 the surface, the neoprene suits were severely distended for several days. The pressure- 

 compensated suits were decompressed instantly by opening the gas valves. 



MALFUNCTION ANALYSIS 



The principal reason for malfunction of the suits was resistance-wire fatigue and consequent 

 failure. Ozone cracking of the natural rubber skin material was evident to a moderate degree. 



