A tension leg platform which can be a heave restrained platform and drilling system (HRP/DS) is taken to the heave restrained mode by rapidly sluicing ballast by gravitational force from a reservoir above the water line. More specifically, a tension leg platform (which has a floating structure floating on a body of water, tethers connected to the floor of the body of water at a locus beneath the floating structure, porches attached to the floating structure having tether receptacles for receiving upper terminations of the tethers, a large reservoir above the water line of the body of water to hold a large amount of liquid ballast above the water line of the body of water and a sluice for rapidly dumping the liquid ballast from the floating structure) is taken to the heave restrained mode by: ballasting down the floating structure with liquid ballast in the reservoir, positioning the floating structure above the locus of attachment of the tethers to the floor of the body of water, positioning the upper terminations of the tethers in the tether receptacles of the porches, and rapidly dumping and sluicing the liquid ballast from the floating structure such that tension is applied to the tethers in a rapid and continuously increasing manner.