6 to which the marine riser 7 is attached with linear rigidity to raise distal ends 5 of the control cylinder units 1 pressurized fluid is directed controllably into pressurized portions of cylinders 18 25 26 32 34 and or 37 regardless of how or whether a fluid return line 38 is employed for different types of pressurization fluids and applications of this invention referring to fig1 pressure transducers 39 in pressure indicative communication from pressurized portions of the control cylinder units 1 have control input lines 40 leading to an automated controller 41 shown in fig1 16 the pressure transducers 39 can be in pressure indicative communication directly with pressurized portions of the control cylinder units 1 and or with fluid pressure tubes 20 at positions in the fluid pressure tubes 20 where pressure readings are not significantly different than at the control cylinder units 1 directly the automated controller 41 and the manual override controller 42 are in proximity to and operated in relation to a driller 39 s control panel with a plurality of operating stations throughout a vessel for safety redundance at select safety positions referring to fig1 the riser tensioner ring 6 can be pressured vertically upward towards the operational floor 3 and from side to side in any direction laterally in order to tension the marine riser 7 while maintaining it in a desired position centrally by appropriate pressurization of cylinders 18 from which piston rods 17 are extended to pivotal.