To best utilize the tapering space of a laminar flow hull, the pressure hull is composed of 6 segments, including the two endcaps. All are ring stiffened pressure hulls, made from 6061-T6 aluminum. The first goal is met by avoiding designs that entrap air. O-ring gland dimensions are minimized, and blind fastener holes are avoided when possible. Two of the 5 hull joints are internally fastened.
All hull joints are face seal designs that have no annular voids, a big source of unwanted air.
The free flow of water outside the hull but inside the fiberglass fairing is ensured by large limber holes where needed. Isopycnal hull design The VMG is a buoyancy driven device that works not in the horizontal plane, as most of the worlds underwater vehicles do, but rather in the vertical plane, constantly profiling the upper 1000 meters of sea. As this or any underwater pressure housing descends in the water, it will do one of three things, gain buoyancy, loose buoyancy, or in the case of a perfectly design isopycnal hull, experience no change its initial buoyancy. This is all a result of the deflection of the hull, or more explicitly a change in its displaced volume, as compared to an equivalent volume of seawater. Typical pressure hulls in this displacement size have a lower compressibility than seawater, commonly about half.