What is Submarine: Definition and 79 Discussions

A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. It is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as "boats" rather than "ships" irrespective of their size.Modern deep-diving submarines derive from the bathyscaphe, which in turn evolved from the diving bell. Although experimental submarines had been built before, submarine design took off during the 19th century, and they were adopted by several navies. Submarines were first widely used during World War I (1914–1918), and are now used in many navies large and small. Military uses include attacking enemy surface ships (merchant and military) or other submarines, aircraft carrier protection, blockade running, nuclear deterrence, reconnaissance, conventional land attack (for example, using a cruise missile), and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration, and facility inspection and maintenance. Submarines can also be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are also used in tourism and undersea archaeology.
Most large submarines consist of a cylindrical body with hemispherical (or conical) ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines, this structure is the "sail" in American usage and "fin" in European usage. A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear, and various hydrodynamic control fins. Smaller, deep-diving, and specialty submarines may deviate significantly from this traditional layout. Submarines use diving planes and also change the amount of water and air in ballast tanks to change buoyancy for submerging and surfacing.
Submarines have one of the widest ranges of types and capabilities of any vessel. They range from small autonomous examples and one- or two-person subs that operate for a few hours to vessels that can remain submerged for six months—such as the Russian Typhoon class, the biggest submarines ever built. Submarines can work at greater depths than are survivable or practical for human divers.

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  1. Massimo

    Calculate the max speed at which a submarine rises/dives

    I'm trying to figure out how I would calculate the rate at which a submarine (or any vaguely cylindrical object) ascends or descends in seawater given a certain buoyancy or change in buoyancy. For example, if my submarine is 2000 feet below sea level and weighs 393 metric tons (with empty...
  2. S

    Gato / Balao Submarine "Can't" vs "Must" Surface on Dead Battery

    I've read a lot about Gato / Balao / Tensch class submarines, the ones America used in WWII, and I can't seem to sort out the specific consequences of a dead battery. A lot of you are diesel experts, so maybe someone here knows? Historical accounts are vague. Dead batteries are certainly a big...
  3. PainterGuy

    Production of oxygen in a submarine

    Hi, I was watching the following video. Around 17:00 the following is said: I tried to balance the chemical equation as presented in the video. Please have a look below. I don't see how the production of iron oxide yields more oxygen in the entire reaction. The heating of sodium chlorate...
  4. Vigardo

    Buckling and modal FEA of a submarine structure

    Dear FEA experts, I'm trying to model the mechanical behavior (static, modal, and buckling analyses) of an underwater floating structure (e.g. submarine capsule or buoy) under hydrostatic pressure by Finite Element Analysis. To obtain feasible results, the structure should be modeled as freely...
  5. Whitestar

    Realism of Seaquest DSV Submarine Design: Fact or Fiction?

    I've often wondered how realistic the Seaquest DSV submarine design was. Here are some attachments I've included: https://www.pinterest.fr/pin/326651779206382460/ I would imagine that having windows on the sub would represent structural weakness and it's overall flatness design would make...
  6. colcol500

    Net force on a Submarine Window?

    I have no idea, I honestly thought that the net force would be zero since the submarine window isn't moving...yikes
  7. T

    How much sea water is needed to keep a submarine still at 30 meters depth?

    Homework Statement A submarine is in water, depth 30 meters. Inside submarine there is default air pressure. Submarine has volume of 125 m³, from which 10 m³ is water tank used for submerging. Submarine weights 123 tons. How large portion of the water tank has to be filled with sea water in...
  8. M

    Find the maximum safe depth of a submarine

    Homework Statement An ocean-going research submarine has a 40.0 cm -diameter window 9.00 cm thick. The manufacturer says the window can withstand forces up to 1.20×106 N . What is the submarine's maximum safe depth? The pressure inside the submarine is maintained at 1.0 atm. ρseawater = 1030...
  9. Helios

    Is Yellow Submarine Still a Must-Watch 50 Years Later?

    I realized that this movie is now 50 years old. That goes for anything else in 1968 of course. This was animation quite different from Disney. A really good band did the music too. Have we seen this movie?
  10. B

    Submarine Buoyancy Differential Equation

    Homework Statement A submarine of mass 80 000 kg is floating at rest (neutrally buoyant) at a depth of 200 m in sea water. It starts pumping out sea water from its ballast tanks at a rate of 600 litres per minute, thus affecting both its mass and the buoyancy force. Determine the vertical...
  11. Richie Smash

    Calculate the resulatant downward force of a submarine on the seafloor

    Homework Statement Hi I have uploaded a picture of a pressure question. It says that there is a submarine 325 m deep, with the sea water of density 1150Kg m-3 and acceleration of gravity 10m/s and the volume of the submarine is 0.2m3 with mass 480Kg They first ask for the upthrust. Then they...
  12. Nik_2213

    Submarine volcanic vents and pumice rafts....

    How deep can a submarine volcanic vent be and still generate a significant pumice raft ? Sadly, Wiki is a stub, and most of the relevant literature is pay-walled. As I understand it, deep vents may generate a lot of pumice, but it never reaches the surface, just stays on the vent's flanks...
  13. Robert House

    What is the impact of storms on submarines?

    Here is a scenario to further explain. Let's say I am traveling inside of a submarine. I travel within a depth of 100 to 600 feet deep or 4 to 19 atmospheres. How would I and my submarine be affected if there were a hurricane, tsunami, or hurricane above the ocean. Furthermore, does the...
  14. Delta Force

    Submarine Waste Heat Disposal?

    How do nuclear submarines (and also newer technologies such as air independent propulsion submarines) get rid of the waste heat generated by their power plants given the high pressure environment they work in and their need for stealth?
  15. Baluncore

    Can Lead Acid Batteries and Sea Water Create Chlorine Gas in Submarines?

    Submarines that had lead acid batteries and were depth charged during WW1 or WW2 sometimes produced chlorine gas inside the submarine. Was that because; 1. Broken batteries leaked sulphuric acid into the bilges where sea water with NaCl had accumulated, or; 2. Leaking seawater flooded the...
  16. H

    Does a moving Submarine Create a Toroidal Vortex?

    Today I learned how easy it is to create and visualize toroidal vortices in a swimming pool. I bet this could be done in a bathtub. Do moving submarines create a big toroidal vortex around themselves?
  17. vincekillics

    Optimizing ROV sinking velocity using buoyancy and resistive force

    Homework Statement A small spherical under water ROV (remotely operated vehicle) has a radius of 0.5m and a mass of 450kg. It sinks or rises in the ocean by taking water on board or pumping it back out again. How much water must it take on board to sink at a constant velocity of 1.2m/s. The...
  18. BubblesAreUs

    Depth and pressure in a submarine

    Homework Statement As a submarine dives, the pressure on its hull.. a. remains constant b. increases c. depends on the decrease in volume of the submarine d . decreases e. depends on the thickeness of the walls of the submarine Homework Equations P = F / A The Attempt at a Solution Not a...
  19. morrobay

    Submarine Outfall For Storm Water Drainage Pipe

    Would a water pump for pressure be required for a submarine outfall for storm water drainage ? Diameter of pipe 2 meters Gradient 50 Horizontal distance from shore to outfall 200 meters depth about 16 meters, sine 50 Or would the pressure from gravity gradient be sufficient to overcome...
  20. ali nemati

    Maximum Thrust force in submarine

    I am designing a submarine in low scale that the max propeller OD is 10 cm, means from center of shaft to propeller edge I have around 5 cm distance. I am trying to find the maximum thrust as this submarine suppose to pull an object inside water pipe. I need to find optimum rpm ,blade number...
  21. S

    Acceleration of Submarine when Ejecting Water from its Tanks

    Brief Summary of Question: One submarine starts with a neutral buoyancy 100m below the surface when it displaces 8.9m^3 of water from its ballast tanks. If the mass of the submarine is 69 metric tons what is the initial, vertical acceleration of the submarine immediately after displacing the...
  22. R

    Echo Time Calculation in Underwater Environments

    Homework Statement A seal sees a shark 53.0 m away and let's out a squeal. If the speed of sound through sea water is 1533 m/s, how long will it take for the echo of the squeal to return to the seal? Homework EquationsThe Attempt at a Solution i used the doppler effect formula and got...
  23. A

    How Does an Underwater Current Affect Submarine Navigation?

    Homework Statement driving his homemade submarine underwater in a nearby lake. His instruments tell him that the sub is traveling at 8 m/s relative to the surrounding water and that the sub is oriented due north (nose pointing north). After two minutes, however, he ends up crashing into a...
  24. O

    Relative motion of a cannonball/submarine

    Homework Statement 1.) A projectile is fired from a submarine traveling horizontally at 20 m/s with respect to the water as shown in the figure below. According to an observer on the submarine, the projectile is fired at 45° with an initial velocity of 60 m/s. After firing the projectile, the...
  25. N

    Projectile motion submarine missle problem

    Homework Statement A submarine-launched missile has a range of 4330 km. (a) What launch speed is needed for this range when the launch angle is 45°? (b) What is the total flight time? (c) What would be the minimum launch speed at a 22° launch angle, used to "depress" the...
  26. B

    Can Bernoulli's Law Increase the Depth Range of Submarines?

    Hi people, It may be a strange question, or impossible, but maybe you could help me out. It's about submarines, high pressure and Bernoulli's law. What if we build some kind of jet engine-like thing on the front of the submarine, not to 'pull' it forward, but to speed up the water...
  27. R

    Calculating the thrust required to turn a submarine deep in the water

    Dear All, I am designing a AUV and trying putting a bow thruster in the front. I am kinda confused that how much power do I need to turn my AUV by a steady angular velocity. Could anyone pls help me with this. Regards
  28. mrspeedybob

    WW2 Airplane Submarine: Can it Really Run Underwater?

    This question may be impossible to answer without specific knowledge of vintage aircraft engines but maybe not. How does this airplane... come out of the wave running? It seems like running a piston engine underwater would result in ingestion of water and hydro-lock. I'm not an...
  29. B

    Pressure on a submarine window

    1. A research submarine has a 20cm diameter window, 8cm thick. The manufacturer says the window can withstand forces up to 10^6N. What is the submarine's maximum safe depth? The pressure inside the submarine is maintained at 1atm. 2. Homework Equations P = P(atmosphere) + ρ*g*h 3. I...
  30. S

    Questsion involving pressure difference due to submarine diving

    Homework Statement A submarine maintains 100 kPa inside it and dives 250 m down in the ocean having an average density of 1030 kg/m^{3}. What is the pressure difference between the inside and the outside of the submarine in kPa?Homework Equations The Attempt at a Solution I am quite confused...
  31. E

    Submarine pressure vessel design

    I'm working on the design for a dry-hull model submarine. My plan is to cast the hull shape that I want out of aluminum because this type of casting is cheap, easy to make, and because aluminum has a good strength to weight ratio. I want the hull to be able to withstand an external pressure of...
  32. bcrowell

    Why does the buoyant force decrease in Supplee's submarine paradox?

    Supplee's submarine paradox arises when you consider a submarine moving horizontally at relativistic speeds. (Never mind that this would obviously destroy the sub.) When at rest, the sub was neutrally buoyant. In the moving sub's frame, the water is more dense, so buoyancy is increased, and the...
  33. C

    MHB Problem from Paper 3 of the 1998 STEP; Probability distribution of Submarine call signs

    I was browsing the 1998 STEP paper 3 (like you do) and come across a question related to a real intelligence gathering problem. It has some simplifications and probably invalid assumptions, but is still quite interesting. The question is: I don't intend to solve this since the only question...
  34. S

    Finding the total pressure acting on a submarine

    Hello I'm having trouble with answering this question: Certain submarines are capable of speeds in excess of 30 knots. What is the total pressure sensed at the nose of a submarine if the vessel is at periscope depth (5 m) and a speed of 30 knots? (Assume a constant sea-water density of 1030...
  35. H

    Max Depth of Submarine Modeling: 80kpa

    Hello, I'm working on a project, and my teacher gave me something to think about, but I am at a loss. He wants me to come up with an equation to model the maximum height a submarine can go underwater, if it can withstand a maximum pressure of 80kpa. I started thinking it was an integral...
  36. P

    Submarine Sinking: Calculate Volume Needed to Flood

    Homework Statement A submarine that weighs 10,000kg in air and has a volume of 12m3 floats in a harbor. How much of its volume do we need to flood in order to just begin sinking it in salt water with a density 1.02 g/cm3? Homework Equations The Attempt at a Solution Fgravity = mass...
  37. K

    A submarine sonar system sends a burst of sound with a frequency of

    A submarine sonar system sends a burst of sound with a frequency of 325Hz. The sound wave bounces off an underwater rock face and returns to the submarine in 8.50s. If the wavelength of the sound is 4.71m, how far away is the rock face? (Ans: 6.51km ) -- v=fλ λ=wavelength f=frequency...
  38. L

    Submarine sonar doppler problem

    Homework Statement A stationary destroyer is equipped with sonar that sends out pulses of sound at 49.0 MHz. Reflected pulses are received from a submarine directly below with a time delay of 60.0 ms at a frequency of 48.966 MHz. If the speed of sound in seawater is 1.58 km/s, what is the...
  39. I

    Calculating pressure to raise a submarine

    ok a model submarine, so not as exciting as the title suggests! This is a pretty basic physics question so forgive me, I'm just trying to clarify in my own head the increase in water displacement with a decrease in gas pressure. Basically as shown in the diagram below I have a model of the...
  40. M

    Understanding Submarine Pressure: Importance and Calculations"

    The pressure in a submarine inside water P=h*ρ*g+Pa Okay, Since there's Atmospheric pressure inside the submarine (Pa),we calculate the total pressure on the submarine from the relation=h*density*g we just neglect the atmospheric pressure why?I don't understand? Why don't we calculate the...
  41. C

    First law of thermodynamics applied to a submarine

    First law of thermodynamics Hallo, i hope someone can help me with the following question: A submarine contaiins 1000m^3 of air and has a temperature and pressure of 15°C and 0.1MPa respectively. Due to the cold seawater a heatflow of 60 MJ/h occurs. The machines on the otherhand add...
  42. C

    First law of thermodynamics applied to a submarine

    First law of thermodynamics Hallo, I hope someone can help me with the following question: A submarine conatins 1000m^3 of air and has a temperature and pressure of 15°C and 0.1MPa respectively. Due to the cold seawater a heatflow of 60 MJ/h occurs. The machines on the otherhand adds...
  43. S

    How Does Submarine Buoyancy Affect Its Movement and Stability?

    Bouyancy Question: A 3000m^3 submarine of mass, m, is filled with air(density air =1.29kg/m^3) and is floating, submergerd, in seawater(density = 1400kg/m^3) a) draw diagram. b) Write an equation that that equates weight of the sub to the buoyant force( include weight of air)? c)...
  44. C

    Total pressure of water against submarine

    Homework Statement What is the total pressure (absolute pressure) against the porthole of a submarine, when the submarine is at a 35 m depth, and the density of the seawater is 1020 kg/m3. Air pressure is 1 bar and 1 bar = 1×105 Pa. Give the result using unit bar. Homework Equations...
  45. A

    Kinematics Question Involving Submarine

    Homework Statement A submarine can use sonar (sound traveling through water) to determine its distance from other objects. The time between the emission of a sound pulse (a “ping”) and the detection of its echo can be used to determine such distances. Alternatively, by measuring the time...
  46. P

    Submarine Distance - Hard Doppler effect

    Homework Statement A French and a U.S. submarine are moving directly towards each other during manoeuvres in still water. The French submarine is moving at 50.0 km.hr-1. It sends out a sonar signal at 1100.0 Hz. The frequency detected by the French submarine (reflected back from the U.S...
  47. R

    Tour Submarine: Deep View 66 Can Descend to What Depth?

    Homework Statement A submarine called the Deep View 66 is currently being developed to take 66 tourists at a time on sightseeing trips to tropical coral reefs. According to guidelines of the American Society of Mechanical Engineers (ASME), to be safe for human occupancy the Deep View 66...
  48. K

    Resistive forces on a submarine?

    Lets say I was going to build a submarine, how could I determine most accurately the resistive forces as it is traveling in sea water at a constant velocity. I need to know how much energy it would consume per km. Cant find anything about this online.. Thanks in advance!
  49. I

    Pressure on a window of a submarine

    Homework Statement a research submarine has a 20 cm diameter window 8 cm think. the manufacturer says the window van withstand forces up to 1x106N. What is the submarine's maximum safe depth? Homework Equations p = po + \rhogd The Attempt at a Solution p = F/A = 1X106 / 0.03 =...
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