60 typically comprises a hydraulically powered unit e g motor 63 that drives roller arm assembly 50 back and forth along an axis defined by roller frame 54 in preferred embodiments lead screw drive assembly 60 is able to be removed subsea to extend its life motor 63 is preferably a 240 cc hydraulic motor which is coupled to lead screw 61 which can vary in length as needed e g from around 1 5 inches to around 5 inches with a typical travel of around 59 inches motor mounting frame 6 fig4 b houses a docking probe receptacle 17 h dual port manifold 7 fig5 g and motor 63 the docking probe receptacle interfaces with the docking probe on the carriage lead screw 61 nut is flanged and is attached to a drive plate the drive plate interfaces with slots on the roller frame in order to drive it back and forth two stainless rods running the length of the screw prevent the drive plate from rotating while the screw is rotating the 17 h manifold provides an rov interface for driving roller arm assembly 50 roller arm assembly 50 slides in and out of carriage weldment 40 on roller frame 54 lead screw drive assembly 60 is removable and interfaces with carriage weldment 40 and roller arm assembly 50 in order to drive roller arm assembly 50 forward and.