and both, for their own purposes, may be 

 correct. For reasons of clarity, definitions of 

 the dimensional and performance terms used 

 in the following descriptions are given below. 

 Definitions of the specific terminology used 

 within these categories can be found in the 

 appropriate chapters. 



Payload: The total weight which may be 

 placed aboard (internally and externally) a 

 submersible after the pilots/observers and all 

 other equipment or supplies are aboard 

 which are required to conduct a dive to its 

 operating depth under routine, safe condi- 

 tions. 



DIMENSIONAL/PERFORMANCE 

 TERMS 



Length, Beam. Height, Draft: See Figure 

 4.1. 



Weight (dry): In-air vehicle weight in a 

 ready-to-dive condition with only operating 

 and hotel equipment aboard. 



Operating Depth: The deepest depth a sub- 

 mersible can operate and maintain a speci- 

 fied safety factor, usually 1.5 or greater. 



Collapse Depth: The computed depth (de- 

 termined by model testing or calculations 

 based on materials testing) at which a pres- 

 sure-resistant structure, e.g., pressure hull, 

 will fail owing to ambient pressure. 



Hatch diameter: Least diameter of the per- 

 sonnel entrance orifice in the pressure 

 hull. Where the opening is a truncated cone 

 this dimension is the minimum diameter. 



Life Support: The total time (in hours), 

 including normal and emergency systems, 

 available to sustain one "average" man 

 within a closed pressure hull. (See Chapter 9 

 for definition of an "average man.") 



Total Power Capacity: Total electrical 

 power, in kilowatt hours (kWh), a submers- 

 ible's power plant can generate to supply 

 propulsion, hotel load and scientific work 

 equipment. Derived from (total voltage .\ 

 ampere hours) /1,000. 



Speed/Endurance: Expressed in knots (6,- 

 080 ft/hr) and calculated, not from total kWh, 

 but from that portion of the power supply 

 devoted to propulsion. The employment of 

 lights, echo sounders and other equipment 

 requiring electrical power will detract from 

 the endurance stated. 



Pilot: The number of individuals required 

 to safely control the submersible in all as- 

 pects of a dive. 



Observers: The number of individuals a 

 submersible may routinely carry on a dive 

 who are in no way required for control of the 

 submersible. 



COMPONENT/SUB-SYSTEM TERMS 



Pressure Hull: The pressure-resistant com- 

 ponent of a submersible wherein the human 

 occupants reside. 



Ballast/Buoyancy: The means whereby a 

 submersible attains negative or positive 

 buoyancy to dive and surface, and to attain 

 small-scale changes in ± buoyancy when 

 submerged. 



Propulsion/Control: The devices a vehicle 

 carries to propel it horizontally (main propul- 

 sion), vertically and laterally (thrusters), and 

 the systems (dive planes and rudders) used 

 to control its attitude (pitch, roll, yaw) under- 

 way. 



trim: The systems available to attain up/ 

 down bow angles (pitch) or list angles (roll) 

 through movement of weights or liquids for- 

 ward or aft, or port/starboard. In some in- 

 stances a builder defines trim as the means to 

 attain small-scale buoyancy adjustments 

 when submerged; where this is the case, it has 

 been included under Ballast/Buoyancy. 



Power Source: The nature and total quan- 

 tity of onboard energy (mainly electrical) 

 carried by the submersible when diving. 



Life Support: The oxygen supply, carbon 

 dioxide removal systems, temperature con- 

 trol devices, atmospheric monitoring instru- 

 ments, etc., carried aboard. 



Viewing: Dimensions, quantity and loca- 

 tion of viewports and other devices providing 

 the occupants of the pressure hull direct 

 viewing of the external envii'onment. 



Operating/Scientific Equipment: Perma- 

 nently installed submersible equipment 

 used: 1) By the operator — to communicate on 

 and under the surface, to monitor vehicle 

 attitude and location and to determine the 

 presence of possible hazards; 2) By the ob- 

 server — to attain environmental information 

 such as water temperature, bottom relief, 



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