Although submersible occupants have 

 learned to cope with such conditions, there is 

 still much to be desired in the way of perma- 

 nent solutions that do not consume an inor- 

 dinate share of the limited electrical power 

 supply. 



Temperature Control: 



Ambient seawater is the major influence 

 on temperature within the pressure hull. 

 The length of time it takes to transfer heat 

 either into or out of the pressure hull de- 

 pends upon the hull material. Figure 9.9 

 shows the temperature variations within the 

 steel-hulled BEN FRANKLIN during its 30- 

 day drift. Comparing this with ambient 

 water temperature reveals a very close cor- 

 relation. An examination of this plot shows 

 another major temperature influence: Dur- 

 ing day 11 the propulsion motors were 



turned on in an attempt to regain the Gulf 

 Stream's central core, the four propulsion 

 motors were activated and the effects of heat 

 generated by their operation is shown by the 

 wide variance between cabin and ambient 

 temperature on that day. Electronic equip- 

 ment is a positive heat source which can be 

 an advantage during a deep dive in cold 

 waters but a disadvantage on shallow dives 

 in warm waters. Other sources of heat are 

 the metabolic activities of the occupants 

 themselves and the chemical reaction in the 

 carbon dioxide scrubber compounds, which is 

 exothermic. These contributions are also ap- 

 parent in Figure 9.9 midday between days 12 

 and 13 when the vehicle was being towed 

 back into the central core and all electronic 

 equipment, except for the underwater tele- 

 phone and a few scientific instruments, was 

 turned off. 



MISSION DURATION, DAYS 



Fig. 9.9 Log of temperature and relative humidity for 30 days aboard BEN FRANKLIN. [From Ref. (16)] 



429 



