Page 19 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

1.1 The ROV 7
FIGURE 1.5
Example of WCROV.
sufficient AC power delivery components and pressure housings capable of achieving deeper depths over longer tether/umbilical lengths. These also are generally all-electric vehicles (powering prime movers (thrusters) and camera movement controls) with some hydraulic power for the operation of manipulators and small tooling package options. The vehicle electrical power is stepped down to a manageable voltage for operation of the various components and can be either AC or DC power. Vehicles in this classification are sometimes termed “light work class” vehicles to fully differentiate them from OCROVs. Due to the weight of these vehicles, a launch and recovery system (LARS) as well as a tether management system (TMS) is often needed.
3. Work class ROVs (WCROV): Vehicles in this category are generally heavy electromechanical vehicles running on high-voltage ( .3000 V) AC circuits from the surface to the vehicle (Figure 1.5). The power delivered to the vehicle generally is changed immediately to mechanical (hydraulic) power at the vehicle for locomotion as well as all manipulation and tooling functions.
4. Special-use vehicles: Vehicles not falling under the main categories of ROVs due to their non-swimming nature such as crawling underwater vehicles, towed vehicles, or structurally compliant vehicles (i.e., non-free-swimming). The special-use vehicle coverage is outside the purview of this text.
The general difference between the OCROV and the MSROV is the power transmission and depth rating. The general difference between the MSROV and the WCROV is the size of the hydraulic power pack and the horsepower rating for the operation of manipulators and tooling. Both the MSROV and the WCROV are deep-rated vehicles and both can be delivered to deep work sites. The WCROV, however, can perform heavier tasks than the MSROV is capable of achieving due to the added muscle of hydraulic actuation of its components (versus the electrical actuation of the MSROV). There are a few “electrical WCROVs” on the market, but the vast majority of the
(Courtesy FMC Technologies.)