Abstract: An ocean platform has a negatively buoyant pontoon suspended from the balance of the platform to increase the heave resonant period to at least 25 seconds. Tendons suspend the pontoon to a depth where dynamic wave forces do not materially act directly on it in seas of normally occurring periods of up to about 15 seconds but do in seas of periods above about 15 seconds. Columns and an upper pontoon provide buoyancy for the platform.

Abstract: A free fall escape vehicle has surfaces of a deceleration structure that decelerate the vehicle upon entry into the water at a rate no greater than 4 g to 10 g by progressively increasing in area towards an escape vessel of the vehicle. In one form, the deceleration structure is circularly symmetrical normal to its axis, which can be approximated by a series of spaced-apart shells, each shell being a zone of a sphere the center of curvature of which is at or above the center of gravity of the escape vehicle; the condition can also be approximated by truncated sections of right circular cones. An escape vehicle similar to a lifeboat has a wedge-shaped deceleration structure with the sides of the wedge paralleling the fore-and-aft axis of the vessel, the structure can be approximated by a series of right circularly cylindrical shells or flat plates both having an effective center of curvature at or above the center of gravity of the vehicle.