rotating in the direction of directional arrow 94 the entire unit 16 39 is caused to angle or tilt which causes the drag skirt to engage in the solids and retard forward motion of the unit as the buoyancy at the top raises the tube into a more vertical angle the drag skirt raises and allows the forward motion of the device to continue the pair of steering propeller units 48 also assist in maintaining the entire cutter transporter unit to maintain a desired substantially vertical alignment referring now to fig1 there are shown details of the drive and mounting of the cutter head s 51 51 39 the cutter head 51 shown in fig1 may be for the dual cutter head form of the invention or the single cutter head form shown in fig8 within the barrel portion 94 is mounted a reversible hydraulic motor 96 having hydraulic lines 98 and 100 connected thereto the output shaft from the hydraulic motor 96 designated 102 is splined to drive a hub 104 which is bolted to the internal center plate at the opposite end of the barrel portion of the cutter 51 is a stub shaft 104 39 which is carried by a stub shaft.