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4.0 PROBLEMS ENCOUNTERED 



The information in this chapter was obtained through personal interviews with 

 a total of 20 operators and builders representing 51 operating vehicles. A 

 secondary source was from published documents (trade journals, transactions, 

 proceedings, etc.). Since the content of this chapter is somewhat critical 

 of the ROV field, individual operators and builders are not identified with 

 their vehicle's problems, except in those instances where the information has 

 been published and is public record. 



The following problem categories are listed in decreasing order of occurrence. 

 Table 4.1 lists the problem areas identified in this study and the number of 

 operators who encountered the problem. , It was not possible in all instances 

 to obtain all the details on each problem area since several operators - owing 

 to time constraints - simply stated that a particular problem had occurred, 

 but was subsequently corrected. 



4 . 1 ENTANGLEMENT 



By far the most prevalent problem today's operator encounters is entanglement 

 of the umbilical cable or the vehicle itself. Entanglement in its most mild 

 form can result in merely a short delay until the problem can be worked out 

 by the operator. In its more serious forms it can lead to abandonment of 

 the vehicle for several months until it can be retrieved or its complete loss. 



The means of entanglement are numerous as the following litany of entanglement 

 incidents demonstrates; 



Operator A - Cable tangled with surface buoy mooring, cut umbilical, vehicle 



later resurfaced and was retrieved. 



Cable fouled on ships propeller, cut umbilical, vehicle lost. 

 Operator B - Cable wrapped around mast of sunken ship, pulled free. 



Vehicle caught within structure of sunken ship, pulled free. 

 Operator C - Cable fouled on bottom structure, vehicle abandoned and 



retrieved three months later by divers. 

 Operator D - Vehicle flew under submerged cable and fouled. 



Cable wrapped around submerged buoy mooring line. 



Cable fouled around surface buoy mooring line. 



Cable cut by unknown object on the bottom. 



Vehicle fouled on its own umbilical. 

 Operator E - Vehicle fouled on discarded cable. 

 Operator F - Cable fouled in support ship's propellers. 



Cable caught on submerged piling. 

 Operator G - Vehicle caught in subsea manifold, subsequently recovered. 

 Operator H - Cable fouled and ruptured by polypropelene mooring lines 



of marker buoys (100 such incidents in 18 months operation) . 



Vehicle caught in corner of structure, later recovered by 



divers. 



Vehicle propeller fouled by monofilament fishing lines caught 



in structure. 



Cable fouled in structure, subsequently was intentionally 



severed, vehicle caught in monofilament line while ascending, 



later freed by divers. 



