Buoyancy systems

A buoyancy system for controlling the descent or ascent of an object in a body of water, comprising, in combination:

• a plurality of inflatable, collapsible, submersible buoys, each of said buoys having an inlet for receipt and discharge of an inflating medium, and being capable of being inflated from a collapsed state of minimum buoyancy to a fully inflated state of maximum buoyancy,
• a source of inflating medium for providing said inflating medium at pressure at least as high as the hydrostatic pressure in said body of water at the greatest depth of submersion of at least one of said submersible buoys;
• and
• a plurality of valve means each connected to the inlet of one of said buoys and to said source of inflating medium, each of said valve means being responsive to variations in the hydrostatic pressure about the buoy to which it is connected when it is submerged in said body of water to control the amount of inflation of said buoy by the addition or removal of inflating medium in said buoy in response to changes in the depth of submergence of said buoy, while maintaining a relatively small pressure differential between the pressure of said inflating medium and said hydrostatic pressure throughout the depths of submergence of said buoy in said body of water.

A buoyancy system for aid in controlling the descent, ascent, and positioning of a vertical riser extending in a body of water from sea bottom to a drillship comprising, in combination:

• a plurality of inflatable, collapsible, submersible buoys positioned at spaced intervals about said riser, each of said buoys having an inlet for receipt and discharge of an inflating medium, and being capable of being inflated from a collapsed state of minimum buoyancy to a fully inflated state of maximum buoyancy,
• a source of inflating medium for providing said inflating medium at pressure at least as high as the hydrostatic pressure in said body of water at the greatest depth of submersion of at least one of said submersible buoys;
• and
• a plurality of valve means each connected to the inlet of one of said buoys and to said source of inflating medium, each of said valve means being responsive to variations in the hydrostatic pressure about the buoy to which it is connected when it is submerged in said body of water to control the amount of inflation of the buoy by the addition or removal of inflating medium in said buoy in response to changes in the depth of submergence of said buoy, while maintaining a relatively small differential between the pressure of said inflating medium in said buoy and said hydrostatic pressure about the buoy throughout the depths of submergence of said buoy in said body of water.