Surfacing Operations

There are a couple different ways a submarine can surface. One method that I am illustrating here is by use of the Low Pressure Blower. The process involves raising the induction mast and turning on the blower. The Officer of the Deck will order the ship to go to periscope depth. The purpose is to make sure the ship will not surface into a high traffic area. When all is clear, the Officer of the Deck anounces on the 1MC "Prepare to Surface." This causes the entire ship to respond by lining up the ventilation system, draining the induction mast, and other various actions. When all stations have reported that they are ready to surface, the OOD orders the Diving Officer to surface the ship. The ship surfaces (with the ballast tanks still full) by driving to the surface. When the ship's ventilation lineup is shifted to direct the low pressure air to the ballast tanks, the blower is energized.



Surfaced When the blower begins to build up pressure, the water is forced out the grates in the bottom of the ballast tanks. As more water is removed, the ship becomes lighter until the force of gravity is overcome by the force of bouyancy and the submarine begins to rise to the surface. Obviously if the main ballast tank vent valves were open, the air would escape out the top and the ship would be unable to empty its ballast tanks and surface. This is the reason the MBT vents are shut when the ship is submerged. In an emergency, high pressure air can be suddenly forced into the tanks to cause a rapid dewatering of the ballast tanks, and the ship will surface.



While the ship is surfaced, the blower is allowed to force water out the ballast tanks until air is observed coming up the sides of the submarine.



The other maner of surfacing is called an Emergency Blow. Air under tremendous pressure that is stored in flasks in the ballast tanks is suddenly forced into the ballast tanks. This creates an instantaneous positive bouyancy (regardless of depth) that causes the submarine to start to surface. As the ship gets closer to the surface the sea pressure decreases and the air expands further to rapidly accelerate the ship to the surface.

This operation is dangerous because the emergency blow can be initiated at any depth, thus if the submarine was at a depth greater than periscope depth, when it breaks the surface a collision could occur with a surface ship.

Emergency Blow!
The spactacular results of an emergency blow!!