You do not have permission to edit this page, for the following reasons:

This IP address has been blocked from editing Wikipedia.
This does not affect your ability to read Wikipedia pages.
Most people who see this message have done nothing wrong. Some kinds of blocks restrict editing from specific service providers or telecom companies in response to recent abuse or vandalism, and can sometimes affect other users who are unrelated to that abuse. Review the information below for assistance if you do not believe that you have done anything wrong.

The IP address or range 3.236.0.0/16 has been blocked (disabled) by ‪ST47‬ for the following reason(s):

The IP address that you are currently using has been blocked because it is believed to be a web host provider. To prevent abuse, web hosts may be blocked from editing Wikipedia.
You will not be able to edit Wikipedia using a web host provider because it hides your IP address, much like a proxy or VPN.
We recommend that you attempt to use another connection to edit. For example, if you use a proxy or VPN to connect to the internet, turn it off when editing Wikipedia. If you edit using a mobile connection, try using a Wi-Fi connection, and vice versa. If you are using a corporate internet connection, switch to a different Wi-Fi network. If you have a Wikipedia account, please log in.
If you do not have any other way to edit Wikipedia, you will need to request an IP block exemption.

How to appeal if you are confident that your connection does not use a web host's IP address:
If you are confident that you are not using a web host, you may appeal this block by adding the following text on your talk page: ((unblock|reason=Caught by a web host block but this host or IP is not a web host. My IP address is _______. Place any further information here. ~~~~)). You must fill in the blank with your IP address for this block to be investigated. Your IP address can be determined here. Alternatively, if you wish to keep your IP address private you can use the unblock ticket request system. There are several reasons you might be editing using the IP address of a web host (such as if you are using VPN software or a business network); please use this method of appeal only if you think your IP address is in fact not a web host.

Administrators: The IP block exemption user right should only be applied to allow users to edit using web host in exceptional circumstances, and they should usually be directed to the functionaries team via email. If you intend to give the IPBE user right, a CheckUser needs to take a look at the account. This can be requested most easily at SPI Quick Checkuser Requests. Unblocking an IP or IP range with this template is highly discouraged without at least contacting the blocking administrator.

This block will expire on 06:21, 30 September 2026.

Even when blocked, you will usually still be able to edit your user talk page, as well as email administrators and other editors.

For information on how to proceed, please read the FAQ for blocked users and the guideline on block appeals. The guide to appealing blocks may also be helpful.

Other useful links: Blocking policy · Help:I have been blocked
Your IP address is in a range that has been blocked on all Wikimedia Foundation wikis. The block was made by ‪Jon Kolbert‬. The reason given is Open proxy/Webhost: See the help page if you are affected .
- Start of block: 05:35, 21 February 2024
- Expiry of block: 05:35, 21 February 2029
Your current IP address is 3.236.201.96. The blocked range is 3.236.0.0/16. Please include all above details in any queries you make. If you believe you were blocked by mistake, you can find additional information and instructions in the No open proxies global policy. Otherwise, to discuss the block please post a request for review on Meta-Wiki. You could also send an email to the stewards VRT queue at stewards@wikimedia.org including all above details.

You can view and copy the source of this page:

((Short description|Structural and hydrodynamic component enclosing the vessel))
((More citations needed|date=February 2010))
[[Image:U995 2004 1.jpg|right|thumb|[[German submarine U-995|''U-995'']], a U-Boat of WWII, showing the typical combination of ship-like non-watertight outer hull with bulky strong hull below]]
A '''submarine hull''' has two major components, the ''light hull'' and the ''pressure hull''. The light hull (''casing'' in British usage) of a [[submarine]] is the outer non-watertight [[Hull (watercraft)|hull]] which provides a [[Fluid dynamics|hydrodynamic]]ally efficient shape. The pressure hull is the inner hull of a submarine that maintains structural integrity with the difference between outside and inside pressure at depth.

==Shapes==
[[Image:SRH025-p40.jpg|thumb|right|[[Type XXI]] U-Boat, late WWII, with pressure hull almost fully enclosed inside the light hull]]

Modern submarines are usually [[cigar]]-shaped. This design, already visible on very early submarines, is called a "[[teardrop hull]]". It is structurally efficient for withstanding external pressure, and significantly reduces the hydrodynamic [[drag (physics)|drag]] on the sub when submerged, but decreases the [[Seakeeping|sea-keeping]] capabilities and increases drag while surfaced.

==History==
The concept of an outer hydrodynamically streamlined light hull separated from the inner pressure hull was first introduced in the early pioneering submarine [[Ictineo I]] designed by the Spanish inventor [[Narcís Monturiol]] in 1859.<ref name="Chaffin2010">((cite book|author=Tom Chaffin|title=The H. L. Hunley: The Secret Hope of the Confederacy|url=https://books.google.com/books?id=pQcjlDMjXFoC&pg=PA55|year= 2010|publisher=Farrar, Straus and Giroux|isbn=978-1-4299-9035-6|pages=55–))</ref><ref name="Stewart2003">((cite book|author=Matthew Stewart|title=Monturiol's Dream: The Extraordinary Story of the Submarine Inventor who Wanted to Save the World|url=https://archive.org/details/monturiolsdream00stew|url-access=registration|year=2003|publisher=Pantheon Books|isbn=978-0-375-41439-8))((page needed|date=August 2019))</ref>  However, when military submarines entered service in the early 1900s, the limitations of their propulsion systems forced them to operate on the surface most of the time; their hull designs were a compromise, with the outer hulls resembling a ship, allowing for good surface navigation, and a relatively streamlined superstructure to minimize drag under water. Because of the low submerged speeds of these submarines, usually well below ((convert|10|kn|km/h|lk=in)), the increased drag for underwater travel by the conventional ship-like outer hull was considered acceptable.((cn|date=November 2021)) Only late in World War II, when technology enhancements allowed faster and longer submerged operations and increased surveillance by enemy aircraft forced submarines to spend most of their times below the surface, did hull designs become teardrop shaped again, to reduce drag and [[acoustic signature|noise]]. [[USS Albacore (AGSS-569)|USS ''Albacore'' (AGSS-569)]] was a unique research submarine that pioneered the American version of the teardrop hull form (sometimes referred to as an "Albacore hull") of modern submarines. On modern military submarines the outer hull (and sometimes also the propeller) is covered with a thick layer of special sound-absorbing rubber, or [[anechoic tile|anechoic plating]], to make the submarine more difficult to detect by active and passive [[sonar]].((cn|date=November 2021))

==Types==
All small modern submarines and [[submersible]]s, as well as the oldest ones, have a single hull.((cn|date=January 2022)) However, for large submarines, the approaches have separated. All Soviet heavy submarines are built with a [[double hull]] structure, but American submarines usually are single-hulled. They still have light hull sections in bow and stern, which house main ballast tanks and provide hydrodynamically optimized shape, but the main, usually cylindrical, hull section has only a single plating layer.

===Light hull===
The double hull of a submarine is different from a ship's double hull. The external hull, which actually forms the shape of submarine, is called the outer hull, casing or light hull. It defines the hydrodynamic performance of submarine, which affects the amount of power required to drive the vessel through the water. This term is especially appropriate for Russian submarine construction, where the light hull is usually made of thin steel plate, as it has the same pressure on both sides. The light hull can be used to mount equipment, which if attached directly to the pressure hull could cause unnecessary stress. The double hull approach also saves space inside the pressure hull, as the ring stiffeners and longitudinals can be located between the hulls. These measures help minimise the size of the pressure hull, which is much heavier than the light hull. Also, in case the submarine is damaged, the light hull takes some of the damage and does not compromise the vessel's integrity, as long as the pressure hull is intact.

===Pressure hull===<!-- This section is linked from [[Type 212 submarine]] -->
Inside the outer hull there is a strong hull, or pressure hull, which withstands the outside pressure and has normal atmospheric pressure inside. The pressure hull is generally constructed of thick high-strength steel with a complex stiffening structure and  high strength reserve, and is divided by watertight [[Bulkhead (partition)|bulkheads]] into several [[Compartmentalization (fire protection)|compartments]]. The pressure and light hulls are separated by a gap in which numerous steel structural elements connect the light hull and pressure hull and form a three-dimensional structure which provides increased strength and buckling stability. The interhull space is used for some of the equipment which can tolerate the high external pressure at maximum depth and exposure to the water. This equipment significantly differs between submarines, and generally includes various water and air tanks. In a single-hull submarine, the light hull is discontinuous and exists mainly at the bow and stern.

Pressure hulls have a circular cross section as any other shape would be substantially weaker.  The construction of a pressure hull requires a high degree of precision. This is true irrespective of its size. Even a one-inch (25&nbsp;mm) deviation from cross-sectional roundness results in over 30 percent decrease of hydrostatic load capacity.<ref>[http://www.usna.edu/naoe/courses/en200/ch10.pdf US Naval Academy]</ref> Minor deviations are resisted by the stiffener rings, and the total pressure force of several million longitudinally-oriented tons must be distributed evenly over the hull by using a hull with a circular cross section.((clarify|What is this supposed to mean? What several million longitudinally oriented tons, and how are they distributed evenly by a circular section? What of the radially oriented pressure forces?|date=January 2022)) This design is the most resistant to [[compressive stress]] and without it no material could resist water pressure at submarine depths. A submarine hull requires expensive [[transverse framing construction]], with ring frames closely spaced to stiffen against buckling instability. No hull parts may contain defects, and all welded joints are checked several times using different methods.

[[Typhoon-class submarine]]s feature multiple pressure hulls that simplify internal design((clarify |how do they simplify internal design?|date=January 2022)) while making the vessel much wider than a normal submarine. In the main body of the sub, two long pressure hulls lie parallel side by side, with a third, shorter pressure hull above and partially between them (which protrudes just below the sail), and two other centreline pressure hulls, for torpedoes at the bow, and steering gear at the stern. This also greatly increases their survivability – even if one pressure hull is breached, the crew members in the others are relatively safe if the submarine can be prevented from sinking, and there is less potential for flooding.((cn|date=January 2022))

==Dive depth==
The [[Submarine depth ratings|dive depth]] cannot be increased easily. Simply making the hull thicker increases the weight and requires reduction of the weight of onboard equipment, ultimately resulting in a [[bathyscaphe]]. This is affordable for civilian research submersibles,  but not military submarines, so their dive depth was always bounded by current technology.

World War One submarines had their hulls built of carbon steel, and usually had test depths of no more than ((convert|100|m|ft)). During World War Two, high-strength alloyed steel was introduced, allowing for depths up to ((convert|200|m|ft)); post-war calculations have suggested crush depths exceeding ((convert|300|m|ft)) for late-war German [[Type VII submarine|Type VII]] U-boats. High-strength alloyed steel is still the main material for submarines today, with ((convert|250|to|350|m|ft)) depth limit, which cannot be exceeded on a military submarine without sacrificing other characteristics. To exceed that limit, a few submarines were built with [[titanium]] hulls. Titanium has a better strength to weight ratio and durability than most steels, and is non-magnetic. Titanium submarines were especially favoured by the Soviets, as they had developed specialized high-strength alloys, built an industry for producing titanium with affordable costs, and have several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems need to be redesigned as well, so test depth was limited to ((convert|1000|m|ft)) for the [[Soviet submarine K-278 Komsomolets|Soviet submarine ''Komsomolets'']], the deepest-diving military submarine. Despite its benefits, the high costs of titanium submarine construction led to its abandonment as the Cold War ended.

==Other types==
There are examples of more than two hulls inside a submarine. The light hull of Typhoon-class submarines houses two main pressure hulls, a smaller third pressure hull constituting most of the sail, two other for torpedoes and steering gear, and between the main hulls 20 MIRV SLBMs along with ballast tanks and some other systems. The [[Royal Netherlands Navy]] [[Dolfijn-class submarine|''Dolfijn''- and ''Potvis''-class submarines]] housed three main pressure hulls. The Russian submarine [[Russian submarine Losharik|Losharik]] is able to dive over 2000 m with its multi-spherical hull.

==See also==
* [[Saddle tank (submarine)]]
* [[Semi-submersible]]

==References==
((Reflist))

[[Category:Submarine design]]
[[Category:Naval architecture]]

Pages transcluded onto the current version of this page (help):

Submarine hull (edit)
Template:Ambox (view source) (template editor protected)
Template:Category handler (view source) (protected)
Template:Citation needed (view source) (protected)
Template:Cite book (view source) (protected)
Template:Clarify (view source) (template editor protected)
Template:Cn (view source) (template editor protected)
Template:Convert (view source) (template editor protected)
Template:Delink (view source) (protected)
Template:Find sources mainspace (view source) (template editor protected)
Template:Fix (view source) (protected)
Template:Fix-span (view source) (template editor protected)
Template:Fix/category (view source) (protected)
Template:Main other (view source) (protected)
Template:More citations needed (view source) (template editor protected)
Template:Page needed (view source) (template editor protected)
Template:Pagetype (view source) (protected)
Template:Reflist (view source) (protected)
Template:Reflist/styles.css (view source) (protected)
Template:SDcat (view source) (protected)
Template:Short description (view source) (protected)
Template:Short description/lowercasecheck (view source) (protected)
Template:Yesno (view source) (protected)
Module:Arguments (view source) (protected)
Module:Category handler (view source) (protected)
Module:Category handler/blacklist (view source) (protected)
Module:Category handler/config (view source) (protected)
Module:Category handler/data (view source) (protected)
Module:Category handler/shared (view source) (protected)
Module:Check for unknown parameters (view source) (protected)
Module:Citation/CS1 (view source) (protected)
Module:Citation/CS1/COinS (view source) (protected)
Module:Citation/CS1/Configuration (view source) (protected)
Module:Citation/CS1/Date validation (view source) (protected)
Module:Citation/CS1/Identifiers (view source) (protected)
Module:Citation/CS1/Utilities (view source) (protected)
Module:Citation/CS1/Whitelist (view source) (protected)
Module:Citation/CS1/styles.css (view source) (protected)
Module:Convert (view source) (template editor protected)
Module:Convert/data (view source) (template editor protected)
Module:Convert/text (view source) (template editor protected)
Module:DecodeEncode (view source) (template editor protected)
Module:Delink (view source) (protected)
Module:Disambiguation/templates (view source) (protected)
Module:Find sources (view source) (template editor protected)
Module:Find sources/config (view source) (template editor protected)
Module:Find sources/links (view source) (template editor protected)
Module:Find sources/templates/Find sources mainspace (view source) (template editor protected)
Module:Message box (view source) (protected)
Module:Message box/ambox.css (view source) (protected)
Module:Message box/configuration (view source) (protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:SDcat (view source) (protected)
Module:String (view source) (protected)
Module:Unsubst (view source) (protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

Return to Submarine hull.

Retrieved from "https://en.wikipedia.org/wiki/Submarine_hull"