I grew up as a “Navy Brat”. For those not familiar with the term it refers to those children who grew up with a parent that served in the Navy. This same “brat” designation applies to each branch of the service, but, I feel it is closer to the truth with those in the Navy. This, in part, is due to the fact that my dad would leave for six months at a time and our mom had to deal with us alone. Then, he would come home and try to change everything. This led to some rather rebellious attitudes for sure. As we got older, my brother started asking more questions about my dad’s job. Dad was stationed on a submarine and life was very different there. They would sometimes not surface for thirty days at a time and my brother had all sorts of questions on how that worked. He wondered how they ate, slept, got clean water, and even fresh air. These were legitimate questions for sure. The one that interested me was how they had fresh air to breathe. Dad explained that they depended heavily on the air filtration, oxygenator, and HVAC systems on board to ensure that they were breathing the right ratio of air. If any of the HVAC, filtration, or air quality systems are not working properly the sub would have to surface to drawn in fresh air. This could be a serious security issue as it would give away their position to anyone who wanted to know. My dad worked as a cook on the submarine so he was really grateful to the electricians and HVAC technicians on board that kept them healthy and safe while submerged for those long days.