326 ENGINEERING EVALUATION 



Ports — The viewing ports in the laboratory and galley were utilized extensively to observe 

 swimmers in the water (visibility permitting), to monitor the interior with externally mounted 

 TV cameras (helium permeation of the TV monitors necessitated removal from the interior), 

 and to provide a diversion in the form of fish watching. The viewing ports presented several 

 problems, as follows: 



1. The flat gaskets installed on the internal pressure-tight covers leaked (four out of 

 eleven ports), preventing full pressurization of the hull on the surface as intended. 



2. Opening and securing of the internal covers was a time-consuming task because of the 

 number of bolts and the torque required to pull down the gaskets. 



'3. The swing of the internal covers consumed excessive space inside the hull. 



4. Removal and replacement of the external port covers was a difficult and hazardous op- 

 eration because of their size and weight. 



5. The cold inside surface of the port light caused moisture condensation, resulting in wet 

 areas around the ports. 



Access Openings — The main access hatch performed its intended purpose well, with no 

 evidence of leakage. Some of the aquanauts had difficulty in entry and exit through this hatch. 

 However, it seems that these difficulties stemmed primarily from lack of space in the entry 

 area and the necessity of climbing the entry ladder in full swimmer dress. 



The surface access hatch was useful for the final systems checkout on surface and for the 

 last-minute stowage of gear. Minor problems associated with this hatch were the lack of 

 counterbalance, making hatch operation difficult, and moisture condensation on the cold surface 

 of the uninsulated hatch, which dripped on the walkway. As a remedy, a plastic sheet was 

 stretched underneath the hatch to shed the water to one side of the walkway. 



The emergency access hatch was fortunately not required. This hatch is considered too 

 inaccessible to serve its intended purpose. 



Entry Trunk — The entry trunk provided ample displacement volume for internal pressure 

 changes and water-pressure variations due to tidal action. The six-foot tidal range experi- 

 enced was somewhat less than the predicted nine-foot range. The maximum recorded water- 

 level excursion was less than two feet. 



Shark Cage — The shark cage, provided for swimmer protection, served little useful pur- 

 pose in this test, since sharks were not a problem. 



Support Structure — The support structure served its intended purpose with little evidence 

 of sinking into the sea bottom. However, because of a late change in site location, the Sealab 

 was placed on an uneven bottom, causing the craft to assume a final attitude having a 6-degree 

 port list and a 6-degree bow-up angle. 



Hull Penetrations — No significant problems were encountered with hull penetrations. 



Variable Ballast — The ballast tanks, generally, functioned as intended. However, difficul- 

 ties with the associated piping and valving were encountered, as discussed under "Ballast Sys- 

 tem," later in this chapter. 



Hull Insulation — The cork insulation used in Sealab II functioned well. The average heat 

 input (60,000 Btu) required to maintain the design temperature (88° F) agreed very closely with 

 the theoretical calculations of heat loss (54,300 Btu). Some additional heat losses not consid- 

 ered in the design calculations were the heat of warm water drained overboard, Arawak gas 

 heat, and electrical transformer heat losses to sea. Minor damage to the insulation was caused 

 when the Sealab partially flooded during the final raising operation. 



