How do Submarines Work

This mini simulator shows the basics of how submarine ballast tanks work.  Control the buoyancy of the submarine by allowing water in to the tanks and see how the submarine responds.



Dive Instructions

1. Open the vents
2. But first close the hatch!

The boat will settle to the bottom as the ballast tanks fill with water. The top vents allow air in the tanks to escape and the bottom vents allow water to enter the tanks.

Surfacing Instructions

1. Close the vents
2. Empty the ballast tanks
3. Open the hatch once you're back on the surface

Once the vents are closed you can empty the ballast tanks by blowing high pressure air into them. The air forces the water out through the bottom vents.

Is this really how submarines dive? Well, it's only part of how it's done. They do use ballast tanks but when they're diving they are also moving through the water. Like an airplane, submarines 'fly' up and down through the water using dive planes and their horizontal tail surfaces.
This animation explains just a few details of ballast tanks. These systems and procedures are in reality very complex. For example, here's a ballast piping diagram from a WWII-era US submarine, the design of which is over sixty years old!

For more information, read Johan Heiswolf's description of submarine ballasting. He covers the subject in more detail and describes some of the variations in design. Also has some material on model submarines.