Fast boats need to be light, but subs, of course, need negative buoyancy.
The ballast systems in most submarines can displace only about 20 percent of the cabin’s volume, but the Hyper-Sub’s ballast chambers double the volume of the cabin. The boat uses a high-pressure pumping system to rapidly fill these chambers with water or air, quickly changing its weight and buoyancy and allowing it to submerge or surface in less than a minute. “This creates more than 12 tons of lift [or sink],” Marion says.