and direction. Few submersibles have run 

 speed trials over measured distances. As a 

 result, the rotor's effectiveness as both a 

 speedometer and odometer is suspect. 



SEA CLIFF and TURTLE employ a differ- 

 ent method to measure speed and distance, a 

 rodmeter. The rodmeter is the speed sensing 

 element of the EM (electromagnetic) log. It is 

 about 12 inches high and 6 inches long, with 

 an airfoil cross section. The active part of the 

 rodmeter is an encapsulated coil which is 

 excited by an indicator transmitter and sets 

 up a magnetic field in the surrounding 

 water. Two insulated pickup buttons, one on 

 either side of the rodmeter, sense the voltage 

 induced in the water (seawater is an electro- 

 lyte) moving past the rodmeter and cutting 

 the magnetic flux set up by the coil. The 

 voltage sensed by the pickup buttons is pro- 

 portional to the speed at which the water 

 moves past the rodmeter and, after process- 

 ing by the indicator transmitter circuitry, it 

 drives the speed and distance indicators. Ac- 

 curacy constraints similar to the rotor at- 

 tend this method. The Doppler sonar, de- 

 scribed later in this chapter, is a far more 

 accurate speed measuring system and is 

 finding increased application. 



Pitch/Roll Indicators: 



For a variety of reasons, including both 

 safety and operational considerations, it is 

 desirable to know and not exceed certain 

 pitch or roll (trim) angles in a submersible. 

 Of all instruments in a submersible, these 

 indicators are the simplest, most reliable and 

 consist merely of a bubble in a liquid con- 

 fined in a curved, degree-marked glass tube. 

 One such device or inclinometer is shown at 

 the top of Figure 10.15 (item 43). Generally, 

 one inclinometer is mounted on the vertical 

 centerline athwartships plane to provide roll 

 angle and one exactly amidships in the vehi- 

 cle's vertical fore and aft plane to provide 

 pitch. In the more sophisticated vehicles, 

 rate of pitch, as well as angle, is measured 

 and displayed as shown in Figure 10.15. 



At this point the detectors, monitors and 

 recorders found on submersibles become 

 unique to each vehicle and a matter of per- 

 sonal philosophy. A similar range of varia- 

 tions is found in the means used to monitor 



and detect the status of various vehicle com- 

 ponents. Table 10.1 lists the most common 

 status indicators. The reasons for wanting to 

 know how much compressed air or battery 

 power is left or if there is a leak in some 

 critical compartment are obvious and need 

 no explanation. Other indicators and mea- 

 surers, as mentioned, either reflect the 

 builder's philosophy concerning what's im- 

 portant to measure on his vehicle or are 

 added to increase its capabilities. Hence, 

 rather than list such personal choices, the 

 reader is referred to Figure 10.15 which de- 

 picts what DEEP QUEST'S designers con- 

 sider to be necessary indicators, detectors 

 and controls. Except for the DSRVs, it is 

 unlikely that any other vehicle exceeds this 

 in scope. It should be noted that this (Fig. 

 10.15) is only one segment of DEEP QUESTs 

 control station and it has been modified since 

 this photograph was taken. 



Communications 



Communication systems in manned sub- 

 mersibles are used for the following pur- 

 poses: Sub-to-ship (surface); sub-to-ship (sub- 

 surface-to-surface); sub-to-diver (subsur- 

 face); atmospheric chamber-to-lock-out 

 chamber (intra-vehicle). Systems which per- 

 form these functions are radio transceivers 

 (AM and FM), underwater acoustic tele- 

 phones and hardwire (sound powered) tele- 

 phones. The following discussion is con- 

 cerned only with routine operational commu- 

 nication requirements and systems; the role 

 of communications to avoid and assist in 

 emergencies is discussed in Chapter 14. 



Surface Communications: (Radio) 



From a routine operational point of view, 

 communications on the surface provide for 

 pre-dive vehicle checkout and status report- 

 ing to the surface ship. Post-dive functions 

 are primarily concerned with rendezvousing 

 with the support ship for subsequent re- 

 trieval. 



During both the pre- and post-dive periods 

 the range between support ship and sub- 

 mersible is maintained at less than 1 mile; 

 hence, short-range surface communication 

 systems serve adequately. Most vehicles rely 

 on line-of-sight, portable radio transceivers 

 in the ultra-high-frequency or citizen's band 



488 



