Medium Sized Vehicles This medium size class of ROV refers to electro-hydraulic vehicles ranging from 20-100 horsepower typically, which can only carry moderate payloads and have limited through-frame lift capability. These ROVs range in weight from 2,205-4,410 lbs (1,000-2,200 kg) with typical payload capacities in the 220-440 lb (100-200 kg) range. They usually carry a single manipulator but the larger of the class can carry two. Some have the capability of through-frame lift of over 992 lbs (450 kg). These vehicles comprise the most widely used ROV class, which evolved from the early "eye ball" systems that were used to observe divers working or to perform routine inspections. This class was developed to perform work, carrying one or two manipulators, in high current conditions. The early ROVs developed, like Perry Tritech’s (originally AMETEK’s) Scorpio (left) and International Submarine Engineering’s Hydra vehicles, are still in operation around the world today. Typical tasks for this class are drilling support, construction support, pipeline inspection and general "call out" work. Modern systems like the Perry Tritech Viper, Super Scorpio and Scorpio Cobra reflect the latest technology applied to vehicles with the same horsepower as their predecessors, but with much greater reliability and efficiency. Most of these systems fall into the 3,281-foot (1,000-meter) depth capability range due to the fact that until recently, the majority of drilling support work has occurred within this depth. Vehicles like the Perry Tritech’s Viper (right), weighing in at 2,205 lbs (1,000 kg), replaced the RECON providing a more powerful, high thrust, electro-hydraulic platform capable of working in 3-knot or greater currents. The larger ROVs such as the Scorpion and Cobra feature 75 hp. and a much-increased work and payload capability while still working at the 3,280 foot (1,000 meter) mark.