145 



on the TV monitor. Initially, the system might view and videotape the image 



in 3-dimensions for subsequent size determinations using photogrammetric techniques. 



Ultimately, a real-time readout and storage of dimensional data is preferable. 



6.1.3 Surface Location Techniques 



A number of ROVs have been lost after their cable has been severed (intentionally 

 or unintnetionally) and the vehicles safely reached the surface. Since the 

 freeboard of all ROVs is no more than 10 to 15cm (and commonly less) , visually 

 locating the vehicle in calm waters is difficult; when the sea state is 2 or 

 greater it is almost impossible. Several vehicles have self-powered, flashing 

 lights to aid in location, however, in 1 to 2m high seas the light will appear 

 intermittently and loses its effectiveness. A surface locating device is 

 required that is light weight, of minimal dimensions and low power drain. 

 The device should combine a variety of sensors to aid in location; at a minimal 

 these should be an acoustic pinger, a radio beacon and a flashing light. Other 

 items which should be considered are some form of pyrotechniques (smoke or 

 flares) , and dye disperents which would activate upon surfacing in an emergency 

 condition. The emergency devices should be designed to aid in location from 

 aircraft, as well as from ships. An operating duration of at least 72 hours 

 is required. 



6.1.4 Thruster/Power Module 



The assistance of ROVs in debris recovery and object retrieval is increasing. 

 However, their performance is limited in the size of cables and lines they can 

 attach because they lack the propulsive power to move and maneuver heavy lines 

 to the point of attachment. 



In another vein, operations under strong, tidally-induced currents are hampered 

 by lack of thruster power and the mission is often rescheduled to work during 

 periods of slack tides. This procedure prolongs the operation and increases 

 its cost. 



An obvious solution would be to increase the power supplied to the thrusters 

 and, concurrently, increase thruster horesepower. The solution, however, 

 increases cable size, which leads to greater drag. 



There is a requirement, therefore, for occassional increased electrical power 

 and thrust, without incurring penalties in cable size. The solution can be 

 obtained by design of a thruster module which is powered by an independent, 

 submersible power source. The source can be batteries which provide high energy 

 for short periods. The module should be designed for easy attachment to a 

 rectangular, open framework structure such that it would augment vehicle 

 thrusting power when the task calls for thrust beyond that required for routine 

 operations. The first step in this project should involve determining the 

 feasibility of such a module in terms of an available power source, adaptability 

 to the field at large and sizing the power requirements based on the projected 

 work tasks. 



