Submarines

Deep ocean pressures are to great for submarines. They do not need to go deep anyway, just to avoid detection by the enemy.

Absolutely - the modern submarine's teardrop shaped hull is a direct result of R&D that eventually led to the design that virtually all modern submarines use today.

Cigar shaped hulls are also used, but like the teardrop hull, they also taper to some extent at the aft portion of the hull, in the Engineering spaces. This is to provide better water flow over the aft control surfaces (rudder and stabilizers). Submarines travel underwater much the same as airplanes do in air, and it is no coincidence they have similar hull shapes.

The result of the modern submarine hull shape allows it to go much faster underwater than it can on the surface (a lot faster). In the past (WWII, e.g.) submarines were essentially surface vessels that had a limited submergence capability, and as such, they were designed to run much faster on the surface than underwater. With the advent of Nuclear Power and hull design changes, the submarine was transformed into a weapons system that could quickly gain the tactical advantage over surface vessels by being able capitalize on the speed given by the hull design.

To change the buoyancy of the boat and allow it to rise and sink in the water.

They had difficulty in combating merchant convoys to and from their overseas allied nations, as German submarines were a huge threat. Their main tactic was the use of depth-charges, which even if they did not hit the submarine directly, created an overpressure effect which could rupture a sub's hull. They also relied heavily upon heavily-armed naval escorts which had the capacity to fire ship-borne torpedoes, as well as upon their own submarines to track and hunt down German and Japanese ones.

Propulsion-wise, there are 2 types - Nuclear Powered and Diesel-Electric. Class-wise, there are several:

Fast-Attack

Ballistic Missile

Guided Missile (e.g., Tomahawk)

Loss of the trim planes would be a pain, but wouldn't be catastrophic. Trim planes work for a submarine much the same way that the tail fins of a plane help keep it stable in flight, but for a submarine it's not as critical unless you're in a combat situation. In most situations the boat would just surface since only helm control is necessary while surfaced, unless you're in heavy seas.

Trim planes (stabilizing fins) are actually a precise control surface that allows finer depth control while moving during submerged operations, but it isn't the only way a boat maintains stability. The boat's trim tanks are the primary stabilization method for leveling control, while the boat's dive planes control ascent & descent through the depths. Trim/Dive tanks also help control depth to a finer degree, helping the boat achieve a state of Neutral Buoyancy underwater, the same way a diver does.

Remember also that even if main hydraulics to the trim planes was lost, they can still be operated manually, although it's not easy hand-pumping it into position. The boat would have to have sustained serious damage for such an occurrence.

periscope

War material.

More than you can afford

Cornelius Drebbel built the first workable submarine in 1620 using the 1578 plans of English mathematician William Bourne. The frame was constructed of wood, and it was wrapped with waterproof leather.

because if a submarine goes under water to deep levels, it needs to hold against the air pressure.

Yes the person said above.. They have to have a MUCH higher ability to withstand the pressure of the water pushing in against the hull of it.

From the very beginning. IJN subs were prowling the US west coast and launched submarine airplanes which bombed Oregon, and fired shells from their deck guns into Santa Barbara California.

Sonar

There are 2 hulls on every modern submarine; the outer hull, known as the superstructure, and the inner hull, known as the pressure hull. The best analogy is that it's like a thermos bottle, the only difference being that instead of air between the inner and outer portions, there's water.

The superstructure is essentially for streamlined submerged travel while underwater, and to house masts and other equipment (line lockers, cleats, MBT valves, topside under-ice sonar fairings, sonar arrays, etc.). The pressure hull on most boats isn't really designed for underwater travel so much as it is to house equipment and crew, and the design itself is spherical/cigar shaped to give it the best pressure resistance.

The inner pressure hull is where the main systems and crew reside. The hull for most boats (save for Russia and China, who use titanium and GRP) are made of durable, flexible steel that compresses and expands with changes in sea pressure as a boat moves through different depths. Hull penetrations from the inner to outer hull (valves, masts, etc.) are carefully inspected and tested before each major operation, and at intervals during the year. One method of sealing everything (or finding problems) is taking a boat to test depth, which is above the crush depth of a submarine. The sea pressure forces tight any seals that may be a bit loose.

Of course if there's something wrong, a catastrophic failure is also possible.

Officially, 1900, when U.S. Submarine Force was founded and using inventor John Holland's gasoline-powered submarine. In 1800s, submarines USS Hunley, USS Alligator served in Civil War.

microwaves are used to warm or cook something. the electricity powers the microwave so it will create heat.

First use was by the military -- RADAR

Usually the country that owns the sub can't even track it, because they are so quiet, but a lucky sonar operator might pick it up. Actual methods are classified and highly sensitive. Satellites look for heat signatures and sonar systems listen for machinery. SOSUS networks have been laid on the ocean floor at strategic locations to monitor the departure and arrival of submarines into and out of enemy ports. However once the submarines travel beyond the monitoring points, the submarine's location is, as has been mentioned, the results of a proficient sonor operation.

Submarines don't have windows, at least not any that are used for viewing outside of the hull while submerged. They are used in some submarines as bridge viewing windows, but they're subjected to ambient sea pressure when the boat submerges, not direct sea pressure like the hull is.

The water is replaced with air which is not as heavy as water for the same volume.

USS Thresher (SSN-593), lead ship of her class, was lost on April 10, 1963, during post-shipyard sea trials. The loss of the Thresher (believed to be the result of a chain of events beginning with a pipe joint failure and frozen air lines) led to the SUBSAFE Quality Assurance program, as well as re-engineering of critical systems and emergency procedure changes.

Nuclear submarines can go for years without the need to refuel their reactors. Diesel Electric submarines only use their Diesels for battery recharging - their primary mode of propulsion is an electric motor. As such, DE's have considerable range and don't have to refuel often since they don't use their diesels that often.

During WWII, diesel engines were the primary mode of propulsion, since submarines of that era were essentially surface ships with submergence capability. But they normally transited on the surface. Today's DE's transit and travel underwater unless they're entering port, and battery technology has extended the average recharge time from a couple of days to weeks.

No one (nobody) knows !!