In 1976, DACOR presented in the market the Nautilus CVS (Constant Volume System), a revolutionary equipment for diver’s buoyancy. The idea of the project was a chamber with rigid shell, functioning like those of submarines, using water as ballast and air for its positive push. In this way, the system was not affected by ambient pressure variations, as it usually happens with standard buoyancy compensators, where their flexible bladder containing air increases or decreases of volume at each depth variation, thus changing diver’s hydrostatic condition. In CVS, hydrostatic balance is obtained at every depth by inflating air to expel surplus water; then, during diving no other maneuvers are needed. In fact, it will be its automatic system equipped with an emergency manual control to maintain unchanged the volume occupied by air, by adding or discharging it every 30 centimeters of depth variation, enough to maintain its pressure equal to the ambient one, thus keeping constant the diver’s hydrostatic balance. Changing the depth, that is the ambient pressure, the only thing that changed was the air density inside its chamber.
CVS was produced for bottles with a diameter of 17 or 18 centimeters; it was not recommended for other tanks; moreover, it was not too easy to use, so that Dacor required the uses to attend to a specific training course. After few years, because of these difficulties, Nautilus was retired.