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Why submarines need a thick hull to go deeper?
Because thin metals will crush under extreme depth
Why are the windows of a submarine so small?
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.
Why are submarines forbidden to sink beyond a limit?
The hull of the submarine will crush or give way if the pressure of the water is too much.
What are devices used by submarines to control density?
Allowing water into, or discharging it to replace by air, ballast-tanks built into the hull.
Are submarines streamlined?
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.
What happen if the hull of submarine ruptured?
All modern submarines are "dual hull" constructed. What you see on the surface is the outer hull, or "superstructure". The inner hull, where the main systems and crew are, is protected by the outer hull. Damage severity of either the outer or inner hulls depends on the boat's depth at the time. If deep enough, it doesn't take much damage to the hull, as sea pressure will be virtually unstoppable, even with the quick-reaction damage control skills of a submarine crew. However, if sea pressure isn't a factor and the flooding can be controlled, then it's possible to survive such a casualty. Again, it depends on the severity of the hull breach, and the depth at the time. Several modern submarines (my old boat included) have survived underwater collisions which produced severe damage.
How submarines float on water?
The air trapped in the hull (this includes the buoyancy tanks) make it lighter than the water it displaces. The buoyancy tanks surround the main hull (where the people and machinery are), and can be flooded to allow the ship to sink. Refilling them with air (from compressed air tanks) allows it to return to the surface.
How does a submarines propeller shaft go through the hull and still leave the submarine watertight?
All submarine screw shafts have seals around the full length of the shaft hull penetration area to prevent water coming in. Shaft seals can be mechanical, hydraulic, etc., but regardless they serve the same purpose.
How long do submarines periscopes extend?
The new photonics masts are much different than the older style periscopes, so they only extend about 30 feet (they don't have a hull penetration). For traditional periscopes, usually around 30-40' above the sail/fairwater. Periscope depth for most modern submarines is about 65'.
Why are submarines depressurized?
They're not - they are pressurized upon submergence to maintain a positive pressure in the boat to detect any hull breaches. Any seal leak or breach, no matter how small, will immediately register on the boat's pressure board.
How do hydroplanes work?
Hydroplanes work by utilizing the principles of buoyancy and hydrodynamics. When a hydroplane is moving forward, its specially designed hull creates lift, which allows the craft to rise up and glide on top of the water. The shape of the hull and adjustable hydrofoils underneath the craft help to maintain stability and control at high speeds.
Are submarines soundproof?
No, the opposite is true. Sound travels through water much better than air,and the steel hull is very good at transferring sound from water to air, or vice versa.The sound of submarines is detected by AWAKS aircraft many miles away, and even from satellites. Although that isn't completely incorrect, all submarines employ ways to reduce sound output (called transients). Some common ones are sound dampeners, floating sound mounts, and vibration reducers. All of these devices have the same objective: prevent vibrations and sounds from escaping the hull. Submarines have always relied on stealth to complete their missions so we wouldn't be very useful if we could be detected by every awacs or fishing trawler passing by. True, some submarines are quieter than others, and any submarine can be given away by a poorly timed transient, but all in all they attempt to minimize sounds passing through the hull. More: Submarines are not sound proof at all. All measures are made to minimize sound transients. Similar to the way your car has motor mounts that are made of rubber to prevent loud sound and vibration from entering the cab a submarine has sound mounts on every piece of equipment that has moving parts. Pipes have small pieces of metal to stop vibrations as fluid passes through it. Motors have mounts. Solid pipes have rubber isolation hoses to separate them from pumps that move back and forth while running. Electronic equipment has sound mounts to prevent hum from entering the deck. Even the deck has its own isolators from the hull. The crew wear soft soled shoes even to reduce the amount of noise they make walking. The outer hull is even cover in rubber tiles to prevent active sonar pings from reverberating off the hull. Something as simple as paint on a sound mount can transmit sound through the hull.
