Spencer was able to produce the carbon fiber shell for the pressure vessel, but an attempt to create carbon fiber end domes wasn’t as successful. “If you’re filament winding the domes, it’s difficult not to have the fibers overlap in a baseball-wound fashion. We tried that and did not get the performance even close to what we had hoped,” says Rush. So the Titan includes the same type of titanium domes found on Cyclops 1.

The team also developed a GFRP insert to fit inside the hull. The titanium end domes and the research and navigation equipment are all attached to this insert so that the CFRP shell won’t be weakened by penetrations into it. Having a removable insert makes it easy to inspect the hull and to change the Titan’s configuration to accommodate five researchers, three researchers or even autonomous operation.

One argument against using composite materials in submersibles has been that they can fail without warning due to a weak point in the carbon fiber or composite structure that shows up only after multiple use cycles. To ensure that doesn’t happen, OceanGate has developed a unique monitoring system that includes both strain gauges and acoustical sensors that listen for any sounds that could indicate all types of failures. “We can hear small things, like air pockets in the resin or the resin collapsing or fibers buckling,” says Rush. If the sounds are different than they were on previous dives, at 1,000 meters or any other depth, the pilot can abort the dive and return to the surface so crews can check the pressure vessel.

The Titan measures 22 feet long, 9.2 feet wide and 8.3 feet high. It features the largest viewport of any deep diving submersible and is equipped with top-line equipment designed for deep sea exploration, including a high-definition camera, sonar and 40,000 lumens of external light. It’s designed to handle site survey and inspection, research and data collection, media projects and more.

Titan’s missions to date have been test dives. Rush made a solo dive to the 4,000-meter level last December. Four months later, he was part of the four-person crew that helped Titan set a world record as the first non-military submersible to carry more than three people 3,760 meters below sea level. Next summer, the Titan will take passengers down to explore the wreck of the Titanic, which rests two miles below the surface of the North Atlantic Ocean.