Fig 13 6 A 250-lb swordfish impaled below /ItWNs viewport (WHOI) 



passes over cliffs or depressions. Most cables 

 are dark and may or may not provide con- 

 trast with their background. In some cases 

 they lay buried beneath the bottom or may 

 be covered with a thin veneer of sediment. In 

 the above situations a submersible is open to 

 snagging the cable with its superstructure, 

 other appendages or its skids. 



A dangerous situation is created by dis- 

 carded or lost cables which may be present 

 anywhere in the ocean and in any configura- 

 tion (Fig. 13.7). Cables laid for power, commu- 

 nication or data transfer purposes are re- 

 ported to cognizant authorities and their 

 location is generally known. In the case of 

 military cables, this may not always be true. 

 There are no requirements for reporting or 

 recording discarded or lost cables. 



Wrecks: The possibility of fouling in rigging 

 or appendages is the main hazard involving 

 wrecks. Because viewing capability is limited 

 in present submersibles, an operator may 

 unwittingly cruise under a boom, spar, or 

 rigging. Corrosion or boring organisms may 

 have so weakened some appendages that the 

 slightest pressure could bring a section of 

 the wreckage down on top of the submersible 

 or wrap a cable or line around its propellers. 



If a wreck is on a steep slope or resting 

 uneasily on the bottom, a slight nudge may 

 cause it to shift in a manner jeopardizing the 

 submersible. 



Some wrecks may lie in depths where truly 

 watertight compartments, containers, air 

 bottles, boilers, and the like are near their 

 collapse point. It is conceivable that a dis- 



633 



