36 



depth, propulsive power, dry weight, etc. , there is little commonality between 

 umbilicals from vehicle- to- vehicle. 



The breaking strength of umbilicals varies according to vehicle weight. Most 

 cables are capable of lifting the vehicle out of the water, but not all follow 

 this procedure. It is more common to either attach a separate length of lift 

 line to the vehicle which is married (taped or tied) to the umbilical and to 

 use this to retrieve the vehicle or to attach a lift line to the vehicle as 

 it is maneuvered to an appropriate location alongside the support ship. 

 Hydro Products RCVs are designed for launch and retrieval without the aid 

 of a separate lift line. The strength member in most cables is Kevlar. 



Most umbilicals are not positively buoyant. Consequently, there is a tendency 

 for the cable to drag on the bottom and abrade or to tangle with objects on 

 the bottom or the vehicle itself when it backs down. To provide positive 

 buoyancy, floats are attached to the cable at intervals for some distance away 

 from the vehicle (100m or thereabouts) . The floats serve to keep the cable 

 up and away from the vehicle and the bottom. In one instance, CONSUB 201, 

 the cable winch is designed to automatically maintain a particular point on 

 the cable at a set altitude above the bottom to prevent dragging. The Hydro 

 Product's vehicles and Marine Unit Technology's SMARTIE operate from a clump 

 or launcher. The cable from ship to clump is negatively buoyant and capable 

 of retrieving both launcher and vehicle. The cable from the launcher to 

 the vehicle is smaller in diameter and positively buoyant. 



Most cables are a single unit combining all conductors within one protective 

 insulation and wrapping. Neoprene or polyurethene constitute the protective 

 outer jacket. One system has four separate cables (power, control, video, 

 sonar) which are tied together and terminate in a clump from which the vehicle 

 operates on a single cable. Diameter of unitized cables range from 6.3mm 

 (0.24 in.) to 38mm (1.5 in.) 



One to three coaxial conductors are used depending upon the vehicle manufacturer. 

 The longest umbilical in use (the U.S. Navy's RUWS) is 6,858m (22,500 ft) and it 

 transmits all power, command and control functions, TV and sonar over a single 

 coaxial cable through use of time-sharing and frequency multiplexing techniques. 



2.1.9 Control/Display Console 



The data and controls required to operate ROVsrange from the very simple to 

 the very sophisticated. Some appreciation for the magnitude of range can be 

 gained from Table 2.4. It is evident that the only commonality in data display 

 is a TV monitor, and a vehicle depth indicator. Proportional joystick controls 

 constitute the only vehicle-to-vehicle commonality in control functions. 



The size and weight of the control/display consoles follows their capabilities 

 accordingly. FILLIPPO weighs 15kg (33 lbs) and occupies O.Oem^ (2 ft^) . 

 RCV-225 weighs 158kg (350 lbs) and occupies 0.34m3 (12 ft3) . SCORPIO weighs 

 159kg and occupies 2.5m3 (89.4 ft^) . Data for CETUS are not available, but 

 a 3.6 by 2.4m (12 x 8 ft) cabin is required to house it and the two operators. 

 CETUS is not the most complex ROV control/display console, the U.S. Navy's 

 RUWS is larger, heavier and contains additional displays and controls. 



