TILETTE series) a hardwire telephone line is 

 held at the surface by a buoy, while a small 

 boat accompanies it and communicates with 

 the occupants below. The disadvantages of 

 this method are obvious, including: Reduced 

 maneuverability, the problems of "buoy 

 keeping" in strong surface currents or winds 

 and the potential for entanglement. The pro- 

 ponents point out, however, that the buoy- 

 hardwire arrangement is inexpensive and 

 also serves as a way to track the submers- 

 ible. 



Sound-powered telephones find application 

 in lock-out submersibles for communications 

 between the diver's and operator's compart- 

 ments. On the JOHNSON SEA LINK a sound- 

 powered phone provides communication be- 

 tween the acrylic operator/observer's sphere 

 and the aluminum diver lockout cylinder. 

 Basically, the sound-powered telephone may 

 rely on one device to both transmit and 

 receive. Sound waves striking a diaphragm 

 cause it to vibrate. The motion of the dia- 

 phragm changes the magnetic field of a per- 

 manent bar magnet adjacent to the dia- 

 phragm, which induces electric current of 

 varying voltage and amperage in a winding 

 connected to an identical device at the other 

 end. These changes travel to the opposite 

 end where identical changes occur in its 

 magnet and cause the diaphragm to repro- 

 duce the original sound. Because the power 

 input is small, so is the range of transmis- 

 sion, but it is quite adequate for the applica- 

 tion and requires no external source of 

 power other than one's voice. 



The most fundamental communications 

 system is frequently used during the pre- 

 dive surface checkout. This consists of prear- 

 ranged arm and hand signals on the part of 

 the diver and submersible operator. There 

 are standard diver hand signals which the 

 Navy Diving Manual illustrates, and these 

 are frequently followed. A few vehicles in- 

 stall a sound-powered telephone in the free- 

 flooding sail which the diver uses to accom- 

 plish the same purpose when on the surface. 



NAVIGATION 



The term navigation, as used herein, refers 

 to the submersible system's ability to an- 

 swer: Where do we go, where are we and 



where have we been? It is important to note 

 that the whole system is involved in supply- 

 ing such answers, because few, if any, vehi- 

 cles have the ability to navigate independ- 

 ently of surface support. The reason is quite 

 simple: Contemporary submersibles are not 

 large enough to carry both surface and sub- 

 surface navigating equipment. The ship- 

 board navigator might rightfully question 

 the inordinate volume requirements of a sex- 

 tant, but, to be quite pragmatic, a sextant or 

 other visual locating devices simply does not 

 provide the accuracy or repeatability re- 

 quired by submersibles in the open sea. To 

 find and reacquire a cable, pipeline or other 

 hardware, for example, the submersible's po- 

 sition at launch must be known to the best 

 accuracy possible so that electrical power 

 will not be consumed merely trying to find 

 the object of interest. To perform this task, 

 electronic aids to navigation have taken 

 precedence over the sextant. 



The means of establishing the surface sup- 

 port platform's geographic location (for sub- 

 sequent extrapolation to the submersible's 

 undersea position) are many and varied. The 

 subject has been treated extensively since 

 man first set out to sea. Hence, surface posi- 

 tioning per se will not be discussed. For what 

 is probably the most comprehensive treat- 

 ment in existence on the methods and means 

 of surface positioning, reference (15), the 

 American Practical Navigator or, more com- 

 monly, Bowditch is recommended. More re- 

 cent developments, applications and problem 

 areas in this subject are presented in refer- 

 ences (16) and (17), the first and second sym- 

 posiums on Marine Geodesy, respectively. 

 Before leaving this subject, it must be real- 

 ized that all present underwater positioning 

 systems are ultimately referred to the sur- 

 face position. Thus, any errors introduced on 

 the surface are carried directly to the sub- 

 surface. Table 10.7 lists selected contempo- 

 rary electronic surface positioning systems 

 and provides an appreciation of the magni- 

 tude of error encountered with each system. 



Determining a submersible's undersea lo- 

 cation relative to the surface fix is ap- 

 proached in two ways: The first involves 

 tracking of the vehicle by the surface ship 

 and requires no related action on the part of 

 the submersible operator; the second ap- 



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