Shaped like an enclosed rowboat, the vessel included ballast tanks for stability and a system ... world's navies have long used highly developed submarines in military operations, scientists ...

Tubes), as was done when too late, instead of to the ballast tanks, as was done at first ... of the S-4 disaster and safety devices for submarines, but on the efficiency of the Navy in general.

The sub featured in the video below is a significant ... And where the first version used a syringe-pump ballast tank to control the depth, this one uses vertical thrusters. The flexible lid ...

There are three main challenges to building a submarine. These are the radio system, building a watertight enclosure, and having some sort of ballast tank to pump water into and out of.