Abstract: The invention relates to a buoyancy device with a constant and adjustable volume intended for any submersible entity capable of submersion at various depth, and comprising at least one float with a flexible member and filled with gas, the pressure of which is adjusted according to the submersion depth, and such that: the membrane is elastic and defines a gas volume that varies according to the elasticity of said membrane and to the relative inner pressure of said volume relative to the outer environment pressure. An expander-discharge system is used for supplying and emptying the gas to or from the inner volume of the float.

Abstract: The invention relates to a buoyancy device with a constant and adjustable volume intended for any submersible entity capable of submersion at various depth, and comprising at least one float with a flexible member and filled with gas, the pressure of which is adjusted according to the submersion depth, and such that: the membrane is elastic and defines a gas volume that varies according to the elasticity of said membrane and to the relative inner pressure of said volume relative to the outer environment pressure. An expander-discharge system is used for supplying and emptying the gas to or from the inner volume of the float.

Abstract: A self-propelled manned submersible vehicle of the type comprising a pressure-resistant capsule (1) serving as a cabin, ballast tanks (3, 8), releasable ballast (7), propulsion units (4) having propellers driven by electric motors, and storage batteries (42), the pressure-resistant capsule (1) comprises a peripheral window constituted by a vertical cylindrical sleeve (19) which is entirely transparent, the sleeve is of sufficient diameter to house a plurality of people sitting side-by-side, and extends upwardly from a hemispherical bottom (14) and downwardly from a spherical cap (16) which is extended by a cylindrical conning tower (21) which is closed by a hatch (22).