How does a submarine adjust its depth?
This answer addresses the modern military submarines. There is a
bit of variation on the theme, and a bit more when considering
other types of boats. When submarines are submerged and underway,
they are neutrally buoyant. The boat is set up this way so that
minimal effort is required to control depth. (If the boat isn't
sinking or trying to float to the surface, the operators can tend
to other things.) With a boat submerged and properly trimmed, the
planes are added to the rudder as the hydrodynamic surfaces. There
are a couple of set-ups for planes. Boats have stern planes back
aft. From there, some have bow planes up front, and some have
planes on the superstructure, or sail (conning tower). A boat will
have stern planes and bow planes, or it will have stern planes and
sail planes. And the planes are used to control the depth. When the
boat needs to surface or dive steeply, the bow and stern planes are
used to "point" the boat in the desired direction. The angle that
the vessel is moving through the water, the "bubble" of the boat,
is changed. By tipping the bow planes up and the stern planes down,
the boat can be pointed to the surface. Tipped oppositely, the boat
heads down. For small changes in depth, both planes are eased in
the same direction. Tip both up a bit, and the boat is pulled up
through the water. And the boat's bubble isn't changed. Tip both
planes down a bit, and the opposite effect results. The boat
remains level while slowly changing depth. On the boats with the
stern planes and the sail (or fairwater) planes, the depth is
changed to dive or surface by using the stern planes in the same
manner as in the boats that have both bow planes and stern planes.
The fairwater or sail planes are not used. But for small changes of
depth, the fairwater planes can be used by themselves. The
fairwater planes are approximately amidships, and by tipping them
up, the "down" force they impart "pushes the boat down" without
changing the bubble of the boat. Make sense? The sail planes take
advantage of the boat's neutral buoyancy. The force generated by
the planes when they are used will act in a way that causes the
boat to sink a bit more or rise a bit more without changing the
bubble of the boat. It remains level while slowly changing depth.
Use the links to look at pictures of boats and check out their
plane configurations.
Steve
Jordan
Ezra
