A crewed submarine is, at its most elemental level, a machine designed to preserve a bubble of air underwater and keep the rest of the ocean out, Popular Science reports. The complexities of submarine design— everything from propulsion to sensors to controls—have to be designed with this overriding purpose in mind. Because the whole of the submarine needs to maintain this careful containment at all times, what might otherwise be a nothing part, like a deck drain assembly, is crucial to the longer-term viability of the submarine. On September 25, shipbuilders General Dynamics Electric Boat, along with Huntington Ingalls Industries, announced that they had successfully used additive manufacturing, also known as 3D printing, to create a part for the Virginia-class submarine Oklahoma.
