A tensioner assembly having a fully extended position, a fully retracted position and a plurality of extended positions there between, for supporting a riser extending downwardly from a platform to a subsea wellhead. The tensioner assembly can have a riser conductor portion, a tension disk, a lower support structure, a plurality of ram tensioner piston rods, a cylinder deck, a plurality of hydraulic stroke cylinders, a plurality of first primary accumulators, a plurality of second primary accumulators, a plurality of first valves, a plurality of secondary accumulators, and a plurality of second valves.