the means of maneuvering is between vehi- 

 cles that rely solely on motors and those that 

 use motors in combination with planes and a 

 rudder. In each case the location and versa- 

 tility of motors and the shape and location of 

 the planes and rudders all vary widely and 

 defy categorization. In an attempt to impose 

 some order into an area dominated by the 

 "free spirit," the following discussion pro- 

 ceeds along the lines of degrees of freedom 

 obtained by the "motors only group" versus 

 the "motor and rudder/planes group." 



To hold this narrative to manageable pro- 

 portions, only the motions obtained by mo- 

 tors, planes and rudder are discussed. As 

 was shown in Chapter 6, submersibles have 

 the ability to gain pitch and roll by virtue of 

 variable ballast tanks, battery shifts, mer- 

 cury transfer and what-not. A discussion of 

 these is not repeated here. Similarly, most 

 submersibles can obtain heave motion by 

 virtue of ballasting or deballasting. Previ- 

 ously mentioned is the control the operator 

 has on motion by merely shifting his weight. 

 Discussed later in this chapter, but directly 

 related to maneuvering capability, is the 

 ability of most vehicles to run their motors 

 at variable speeds independently of each 

 other and in opposing directions. This fea- 

 ture provides a great deal of the yawing 

 capability on vehicles where two motors are 

 used for main propulsion. 



A variety of other maneuvering options 

 are available. For example, DEEP QUEST 

 can attain a high upward pitch angle while 

 stationary on the bottom by transferring 

 mercury from forward to aft, ALUMINAUT 

 used its manipulators to climb hand-over- 

 hand up the side ofALVIN in 1969 to insert a 

 toggle in ALVIN's hull, and NEMO can attain 

 heave by reeling its anchor in or out in a yo- 

 yo-like fashion. In actual operations, these 

 and other options are brought into play to 

 provide virtually any motion or maneuver 

 desired. These options must be added to the 

 basic degrees of freedom motions discussed 

 below. 



Propulsive Control 

 Thrust and Yaw: 



The most basic of motions, to move forward 

 (or backward) and change heading (under- 

 way or bottomed), are obtained by: 



a) Two port/starboard reversible propellers 

 fixed in a horizontal position and 

 mounted either amidships or on the 

 stern. By slowing down or reversing one 

 propeller the vehicle can be made to 

 yaw. Submersibles in this category are 

 DS~4000 (Fig. 8.18a), PISCES I, 11, III, 

 IV and V, SP-3000, SDL-1 , FNRS-2 & 3 

 and SNOOPER. 



b) Two reversible stern propellers with a 

 lateral bow thruster for additional help 

 in changing heading. TRIESTE II (Fig. 

 8.18b) uses this method. 



Thrust, Yaw, Heave: 



Adding the ability to maneuver vertically 

 up or down to that of traversing and chang- 

 ing course, the following procedures are fol- 

 lowed: 



a) Two port/starboard fixed, reversible pro- 

 pellers capable of being rotated 360 de- 

 grees in the vertical plane. NEMO (Fig. 

 8.18c) used this arrangement (its shape 

 and low center of gravity held it in a 

 vertical position) in addition to an an- 

 chor and winch for heave motions. 



b) One {ARCHIMEDE) or two {DEEP 

 VIEW) stern-mounted, reversible propel- 

 lers, one lateral thruster and one verti- 

 cal thruster (Fig. 8.18d). 



Thrust, Yaw and Sidle: 



Two vehicles can be found with this capa- 

 bility, MERMAID (Fig. 8.18e), which uses a 

 reversible stern propeller and two lateral 

 thrusters (one fore, one aft), and NEREID 

 which uses a trainable, reversible, stern pro- 

 peller in conjunction with a fixed, reversible 

 lateral thruster mounted forward. 



Thrust, Yaw, Heave, Pitch: 



The greatest number of submersibles us- 

 ing only motors for maneuvering fall into 

 this group, and the ways to achieve these 

 motions are quite varied: 



a) Two reversible propellers mounted port 

 and starboard amidships and capable of 

 rotating 360 degrees in the vertical 

 plane. Vehicles using this system are all 

 small and consist of the All Ocean In- 

 dustries' vehicle, GUPPY, K-250 (Fig. 

 8.18f), STAR I, ASHERAH, BENTHOS 

 V, SURV and TOURS 64 & 66. A roll 

 motion can be placed on these vehicles 

 by directing one propeller's thrust up- 



383 



