Page 152 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

140 CHAPTER 6 Thrusters
It was not all that long ago that offshore companies were discussing the possibility of working in 10,000 ft (3000 m) depths. Now it is commonplace and the vehicles to support that work are readily available. Operations in depths of 13,000 ft (4000 m), and much deeper, are definitely in the queue and the vehicles to work efficiently at those depths will be required. As electric actuator power densities continue to improve, the electric tools and manipulators should be coming to sup- port the deep all-electric vehicle. Schilling Robotics is poised to offer an all-electric version of their HD ROV if the market wants it.
However, going back to the beginning of this section and the design spiral that was discussed, the choice of the type of vehicle is actually straightforward. The smallest, lightest simplest vehicle with the least impact on the support platform, and the pocketbook, that meets the operational requirements is the one to choose. It will all start with the capability of the working end of the sys- tem and end with the size of the umbilical and tether. Unfortunately, as the engineer who performs the necessary design spiral iterations will soon realize, that answer does not come easily, and the electric versus hydraulic debate will continue.