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Gato-class submarine

The Gato class of submarines were built for the United States Navy and launched in 1941–1943. Named after the lead ship of the class, USS Gato (SS-212), they were the first mass-production U.S. submarine class of World War II.

The Gatos, along with the closely related Balao-class submarine and Tench-class submarinees that followed, accounted for most of the Navy's World War II submarines; they destroyed much of the Japanese merchant marine and a large portion of the Imperial Japanese Navy. In some references, the Gatos are combined with their successors, especially the Balao class.

Gato's name comes from a species of small catshark. Like most other U.S. Navy submarines of the period, ships of the Gato class were given the names of marine creatures.

AA-1 class and V-boats
The Gato-class ships were considered to be fleet submarines, designed to operate as adjuncts to the main battle fleet, based on standard-type battleships since World War I. They were to scout out ahead of the fleet and report on the enemy fleet's composition, speed, and course, then they were to attack and whittle down the enemy in preparation for the main fleet action, a titanic gun battle between battleships and cruisers. This was an operational concept born from experience in World War I. To operate effectively in this role, a submarine had to have high surface speed, long range and endurance, and heavy armament. Limitations in submarine design and construction in the 1920s and 1930s made this combination of qualities very difficult to achieve. The U.S. Navy experimented constantly with this concept in the post-World War I years, producing a series of submarines with less than stellar qualities and reliability, the AA-1-class submarine (also known as the T class) and the V-boats, of which V-1 through V-3 were an unsuccessful attempt to produce a fleet submarine.

Tambor and Gar class
By 1931, the experimental phase of fleet submarine development was over and the Navy began to make solid progress towards what would eventually be the Gato class. By 1940, a much better developed industrial base and experience gained from the Porpoise-, Salmon-class submarine-, and Sargo-class submarine ships resulted in the Tambor and Gar classes. Finally, the U.S. Navy had hit the right combination of factors and now had the long-desired fleet submarine.

Timing, however, conspired against the actual use of these ships in their assigned role. The attack on Pearl Harbor on 7 December 1941 destroyed the Pacific Fleet battle line and along with it the concept of the battleship-led gun battle, as well as 20 years of submarine strategic concept development. It left the fleet submarine without a mission. Fortunately, the same capabilities that would have enabled these submarines to operate with the fleet made them superbly qualified for their new mission of commerce raiding against the Japanese Empire.

Timing, however, also conspired to make the Gatos a mass-produced class of submarines. Six units were planned in FY41. In the immediate aftermath of the Two-Ocean Navy Act 48 additional units were ordered. By the end of 1941, 33 Gato keels had been laid.

Gato class
The Gato-class design, with a top range of 11,000 nautical miles (20,000 km), was a near-duplicate of the preceding Tambor- and Gar-class ships. The only significant differences were an increase in diving depth from 250 ft to 300 ft, and an extra five feet in length to allow the addition of a watertight bulkhead dividing the one large engine room in two, with two diesel generators in each room. The Gatos, along with nearly all of the U.S. Navy fleet-type submarines of World War II, were of partial double-hulled construction. The inner pressure-resisting hull was wrapped by an outer, hydrodynamic hull. The voids between the two hulls provided space for fuel and ballast tanks. The outer hull merged with the pressure hull at both ends in the area of the torpedo room bulkheads, hence the "partial" double hull. Operational experience with earlier ships led the naval architects and engineers at the Navy's Bureau of Construction and Repair to believe that they had been unduly conservative in their estimates of hull strength. Without changing the construction or thickness of the pressure hull steel, they decided that the Gato-class ships would be fully capable of routinely operating at 300 feet, a 50 foot increase in test depth over the preceding classes.

The Gatos were slow divers when compared to some German and British designs, but that was mostly because the Gatos were significantly larger ships. Sufficient fuel bunkerage to provide the range necessary for 75-day patrols from Hawaii to Japan and back could be obtained only with a larger ship, which would take longer to submerge than a smaller one. Acknowledging this limitation, the bureau designers incorporated a negative (sometimes called a "down express") tank into the design, which was flooded to provide a large amount of negative buoyancy at the start of the dive. Based on later wartime experience, the tank was normally kept full or nearly full at the surface, then emptied to a certain mark after the ship was submerged to restore neutral buoyancy. At the start of the war, these ships could go from fully surfaced to periscope depth in about 45–50 seconds. The superstructure that sat atop the pressure hull provided the main walking deck when the ship was surfaced and was free-flooding and full of water when the ship was submerged. When the dive began, the ship would "hang" for a few extra seconds while this superstructure filled with water. In an attempt to speed this process, additional limber, or free-flooding, holes were drilled and cut into the superstructure to allow it to flood faster. By midwar, these measures combined with improved crew training got dive times down to 30–35 seconds, very fast for such a large ship and acceptable to the ship's crew.

The large size of these ships did negatively affect both surfaced and underwater maneuverability when compared to smaller submarines. No practical fix for this was available due to the limitations of the installed hydraulic systems used to move the rudder. Although a point of concern, the turning radius was still acceptable. After the war, a few fleet ships were fitted with an additional rudder topside at the very stern.

The class of ships had numerous crew comforts including showers, air conditioning, refrigerated storage for food, generous freshwater distilling units, clothes washers, and bunks for nearly every crew member; these were luxuries virtually unheard of in other navies. The bureau designers felt that if a crew of 60–80 men were to be expected to conduct 75-day patrols in the warm waters of the Pacific, these types of features were vital to the health and efficiency of the crew. They could be added without impact to the ship's war fighting abilities due to the extra room of the big fleet ship. The air conditioning in particular had a very practical application, too, besides comfort. Should a submarine submerge for any length of time, the heat generated by the recently shut-down engines, electronic gear, and 70 warm bodies will quickly raise internal temperatures above 100 F. High humidity generated by tropical waters will quickly condense and begin dripping into equipment, eventually causing electrical shorts and fires. Air conditioning, acting mostly as a dehumidifier, virtually eliminates this problem and greatly increases mechanical and electrical reliability. It proved to be a key factor in the success of these ships during World War II.

Mine armament
Like the previous Tambor/Gar classes, the Gato class could substitute mines in place of torpedoes. For the Mk 10 and Mk 12 type mines used in World War II, each torpedo could be replaced by as many as two mines, giving the submarine a true maximum capacity of 48 mines. However, doctrine was to retain at least four torpedoes on mine laying missions, which further limits the capacity to 40 mines, and this is often stated as the maximum in various publications. In practice during the war, submarines went out with at least 8 torpedoes, and the largest minefields laid were 32 mines. Post-war, the Mk 49 mine replaced the Mk 12, while the larger Mk 27 mine (in actuality an acoustic-homing torpedo) was also carried which only allowed one mine replacing one torpedo.

Engine changes

Twelve submarines of this class built by Electric Boat (SS-253 to SS-264) received what would be the final installations of the Hooven-Owens-Rentschler (H.O.R.) double-acting diesel engine. The Navy had been tinkering with this engine off and on since 1937 because its unique design promised nearly twice the horsepower in a package the same size as other diesel engine types. Unfortunately, the Hooven-Owens-Rentschler company ran into severe design and manufacturing problems, and these engines proved to be operational and maintenance nightmares. Frequent breakdowns and utter unreliability had destroyed these engines' reputation with the Navy and they were all removed at the first opportunity and replaced by General Motors Cleveland Model 16-278A V-type diesels. The other Gato-class ships received either the Fairbanks-Morse 38D 8-1/8 nine-cylinder opposed-piston engine or the General Motors Cleveland Model 16-248 V-type as original installations. These engines were hardy, rugged, and well liked by the crews and served the ships quite well. Both the Fairbanks-Morse and General Motors engines were two-stroke cycle types.

Two manufacturers supplied electric motors for the Gato class. Elliott Company motors were fitted primarily to boats with Fairbanks-Morse engines. General Electric motors were fitted primarily to boats with General Motors engines, but some Fairbanks-Morse boats received General Electric motors.

Fairwater changes
At the beginning of the war, Gato-class ships, as well as the Gar and Tambor classes, had fully shrouded fairwaters visually similar to modern nuclear submarines. Experience during the war led to the progressive reduction of this structure to reduce visibility and radar profile at the expense of underwater performance and foul-weather operating comfort. Most of the subs in postwar movies show the final result of these modifications. A side benefit of these modifications was the creation of convenient locations for antiaircraft guns.

Ships in class
Seventy-seven of these ships were commissioned from November 1941 (USS Drum (SS-228)) through April 1944 (USS Croaker (SS-246)). Twenty of the 52 U.S. submarines lost in World War II were of this class, plus USS Halibut (SS-232), a damaged ship that returned to the U.S., but was considered a constructive total loss and not repaired.

Occasionally, some confusion arises as to the number of Gato-class submarines built, with some sources listing the total as 73, due to the transitional nature of the first four ships (SS-361 through SS-364) constructed under the second contract by the Manitowoc Shipbuilding Company of Manitowoc, Wisconsin. These were originally intended to be Balao-class subs and were assigned hull numbers that fall in the middle of the range of numbers for the Balao class (SS-285 to SS-416, SS-425, and SS-426). Manitowoc was a designated follow-on yard to Electric Boat; they used construction blueprints and plans supplied by Electric Boat and used many of the same suppliers. The government-owned shipyards (Portsmouth Naval Shipyard and Mare Island Naval Shipyard) began to make the transition to the new Balao design in the summer of 1942. Electric Boat, due to the huge backlog of Gato-class construction, was not ready to make the transition to the new design until January 1943. Manitowoc had already completed their allotted production run of Gatos and could not switch over to the Balao design until Electric Boat supplied them with the plans. Faced with a work stoppage while they waited for Electric Boat to catch up, managers at Manitowoc got permission to complete four additional boats (SS-361 through SS-364) to Electric Boat's Gato-class plans. Manitowoc's first Balao-class ship was USS Hardhead (SS-365).

World War II
The Gato boats were authorized in appropriations for Fiscal Year 1941, as part of President Franklin Roosevelt's proclamation of "limited emergency" in September 1939. The first boat laid down was actually USS Drum (SS-228) at Portsmouth Naval Shipyard on 11 September 1940. She was commissioned on 1 November 1941, and was the only Gato-class ship in commission when the war started. Gato herself was laid down on 5 October 1940 by the Electric Boat Company at Groton, Connecticut, and commissioned 31 December 1941. Due to their large construction capacity, more than half (41) of the class was built at Electric Boat facilities; three new slipways were added to the north yard and four slipways were added to the south yard to accommodate their production. In addition, the government purchased an old foundry downstream from the main yard, constructed 10 slipways, and turned the yard over to Electric Boat. Called the Victory Yard, it became an integral part of Electric Boat operations. A total of 77 Gatos were built at four different locations (Electric Boat, Manitowoc, Portsmouth, and Mare Island).

All of the Gatos (with one exception, USS Dorado (SS-248)) would eventually fight in the Pacific Theater of Operations. However, in the summer of 1942, six new Gatos were assigned to Submarine Squadron 50 and sent to Rosneath, Scotland, to patrol the Bay of Biscay and to assist in the Operation Torch landings in North Africa. All in all, they conducted 27 war patrols, but could not claim any verified sinkings. Considered a waste of valuable resources, in mid-1943, all six ships were recalled and transferred to the Pacific.

Once they began to arrive in theater in large numbers in mid-to-late 1942, the Gatos were in the thick of the fight against the Japanese. Many of these ships racked up impressive war records: USS Flasher (SS-249), USS Rasher (SS-269), and USS Barb (SS-220) were second, third, and fourth based on tonnage sunk by U.S. submarines. USS Silversides (SS-236), Flasher, and USS Wahoo (SS-238) were third, fourth, and seventh place on the list for the number of ships sunk. Gato-class ships sank four Japanese submarines: JAPANESE SUBMARINE I-29, JAPANESE SUBMARINE I-168, JAPANESE SUBMARINE I-351, and JAPANESE SUBMARINE I-42; while only losing one in exchange, USS Corvina (SS-226) to JAPANESE SUBMARINE I-176.

Their principal weapon was the steam-powered Mark 14 torpedo in the early war years, with the electric Mark 18 torpedo supplementing the Mark 14 in late 1943. Due to a stunted research-and-development phase in the Depression-era 1930s, and in great part due to the arrogance and stubbornness of its designer, the Naval Torpedo Station Newport under the Bureau of Ordnance, the "wonder weapon" Mark 14 proved to be full of bugs and very unreliable. They tended to run too deep, explode prematurely, run erratically, or fail to detonate. Bowing to pressure from the submariners in the Pacific, the bureau eventually acknowledged the problems in the Mark 14 and largely corrected them by late 1943. The Mark 18 electric torpedo was a hastily copied version of captured German G7e torpedoes and was rushed into service in the fall of 1943. Unfortunately, it also was full of faults, the most dangerous being a tendency to run in a circular pattern and come back at the sub that fired it. Once perfected, both types of torpedoes proved to be reliable and effective weapons, allowing the Gatos and other submarines to sink an enormous amount of Japanese shipping by the end of the war.

The Gatos were subjected to numerous exterior configuration changes during their careers, with most of these changes centered on the conning tower fairwater. The large, bulky original configuration proved to be too easy to spot when the boat was surfaced; it needed to be smaller. Secondly, the desire to incorporate new masts for surface- and air-search radars drove changes to the fairwater and periscope shears. Third, additional gun armament was needed, and cutting down the fairwater provided excellent mounting locations for machine guns and antiaircraft cannon. The modifications (or mods) to the Gato-class conning tower fairwaters were fairly uniform in nature and they can be grouped together based on what was done when:

 * Mod 1 – This is the original configuration with the covered navigation bridge, the high bulwark around the aft "cigarette" deck, and with the periscope shears plated over. All the early boats were built with this mod and it lasted until about mid-1942.
 * Mod 2 – Same as mod 1, but with the bulwark around the cigarette deck cut down to reduce the silhouette. This also gave the .50 caliber machine gun mounted there a greatly improved arc of fire. Began to appear in about April 1942.
 * Mod 3 – Same as mod 2, but with the covered navigation bridge on the forward part of the fairwater cut away and the plating around the periscope shears removed. In this configuration, the Gatos now had two excellent positions for the mounting of single 40 mm Bofors or twin 20 mm Oerlikon antiaircraft cannon, an improvement over the .50 caliber machine gun. This mod started to appear in late 1942 and early 1943.
 * Mod 4 – Same as the mod 3, but with the height of the bridge itself lowered in a last attempt to lessen the silhouette. The lowering of the bridge exposed three I-beams on either side of the periscope shears. These exposed beams gave rise to the nickname "covered wagon boats". Began to appear in early 1944.

Variations on the above mods included the 1A (shortened navigation bridge), 2A (plating removed from periscope shears), and the 3A and 4A (which moved the SJ radar mast aft of the periscopes). The conning tower fairwater of Flasher is preserved in Groton, Connecticut, in the mod 4A configuration, with two single 40 mm Bofors mounts.

Deck guns varied during the war. Many targets in the Pacific War were sampans or otherwise not worth a torpedo, so the deck gun was an important weapon. Most ships began the war with a 3-inch (76 mm)/50 caliber Mk. 17 gun (although some ships received older Mk. 6 mounts due to shortages). The 3-inch gun was the model originally specified for the Gato class, but war experience led to the removal of 4-inch (102 mm)/50 caliber Mk. 9 guns from old S-class submarines to equip front-line ships. Beginning in late 1943, almost all were refitted with a 5-inch (127 mm)/25 caliber Mk. 17 gun, and some ships had two of these weapons. Additional antiaircraft guns included single 40 mm Bofors and twin 20 mm Oerlikon mounts, usually one of each.

Notable examples

 * USS Albacore (SS-218) sank the JAPANESE AIRCRAFT CARRIER Taihō. Taihō was the flagship of Vice-Admiral Jisaburo Ozawa's fleet during the Battle of the Philippine Sea and at the time Japan's newest carrier.
 * USS Barb (SS-220), on her 12th patrol in July 1945, landed a small team from her crew on the shore of Patience Bay on Karafuto. They placed charges under a railroad track and blew up a passing train. Barb also conducted several rocket attacks against shore targets on this same patrol, the first ever by an American submarine. They used 5-inch unguided rockets fired from a special launching rack on the main deck.
 * USS Cavalla (SS-244) sank the JAPANESE AIRCRAFT CARRIER Shōkaku. Shōkaku was one of six Japanese carriers that had participated in the attack on Pearl Harbor.
 * USS Cobia (SS-245) sank a ship carrying Japanese tank reinforcements that were en route to Iwo Jima.
 * USS Cod (SS-224) went to the rescue of a grounded Dutch submarine HNLMS O-19, taking its crew on board and destroying the submarine when it could not be removed from the reef, the only international submarine-to-submarine rescue in history.
 * USS Corvina (SS-226) was the only U.S. submarine sunk by a Japanese submarine (JSUB I-176) during the Second World War.
 * USS Darter (SS-227) along with USS Dace (SS-247) conducted an aggressive and successful attack against Japanese fleet units during the lead up to the U.S. invasion of Leyte Island in the Philippines in October 1944. The two boats sank the heavy cruisers JAPANESE CRUISER Atago and JAPANESE CRUISER Maya and severely damaged the heavy cruiser JAPANESE CRUISER Takao. A few hours later, while maneuvering back to the scene to finish off the crippled Takao, Darter ran hard aground on Bombay Shoal off Palawan. Her entire crew was rescued and subsequent attempts to destroy the wreck were only partially successful. As late as 1998, portions of Darter's hulk were still visible on the reef.
 * USS Finback (SS-230) recovered downed pilot LTJG George H. W. Bush, future President of the United States, after his Grumman TBM Avenger torpedo bomber was damaged and eventually ditched during a bombing mission at Chichi-jima in the Pacific.
 * USS Flasher (SS-249) was the second-highest scoring U.S. ship of the war, with 100,231 tons officially credited to her by the Joint Army–Navy Assessment Committee (JANAC).
 * USS Growler (SS-215)'s skipper, Howard W. Gilmore, earned the submarine force's first combat Medal of Honor for sacrificing his life to save his boat and his crew. Alone on the bridge after being wounded by enemy gunfire, and unable to reach the hatch after he had ordered the others below, he pressed his face to the phone and uttered the order that saved his ship and sealed his doom: "Take 'er down!"
 * In USS Grunion (SS-216), Mannert L. Abele earned the submarine force's first Navy Cross, when his boat engaged in a running battle with Japanese ships off Kiska in July 1942. Grunion was subsequently lost in this action. In 2006 and 2007, expeditions organized and led by Abele's sons, Bruce, Brad, and John, located and photographed the wreck of the Grunion using side-scan sonar and a remotely operated vehicle.
 * USS Halibut (SS-232) was essentially the 53rd U.S. submarine loss of the war. Terribly damaged in an aircraft-borne depth charge attack on 14 November 1944, she barely limped back to port in Saipan. Temporarily patched up, she was sent back to the United States. Examined by engineers, she was found to be beyond economical repair and was decommissioned on 18 July 1945, never having made another war patrol. Her entire crew survived.
 * USS Harder (SS-257) was commanded by Samuel D. Dealey, the only submarine commander of the war (perhaps the only one ever) to sink five enemy destroyers, four in a single patrol.
 * USS Mingo (SS-261), which sank two Japanese ships during her patrols, was lent to the Japanese Maritime Self Defense Force after the war, serving under the name Kuroshio.
 * USS Rasher (SS-269)'s notable record during World War II included eight patrols in the Pacific. She sank the third- or second-most tonnage during the war. She served the U.S. Navy until 1967.
 * USS Silversides (SS-236) is officially credited with sinking 23 ships, the third-most of any allied World War II submarine, behind only USS Tang (SS-306) and USS Tautog (SS-199), according to JANAC figures.
 * USS Trigger (SS-237) became famous in Edward L. "Ned" Beach's book Submarine! (which was a kind of eulogy to her).
 * USS Tunny (SS-282) sank the Japanese submarine I-42 on the night of 23 March 1944, after the two subs dueled for position for over an hour. A week later, Tunny engaged the JAPANESE BATTLESHIP Musashi and inflicted enough damage for Musashi to return to dry dock for repairs.
 * USS Wahoo (SS-238), commanded by one of the submarine force's most famous skippers, Dudley W. "Mush" Morton, engaged in a running gun and torpedo battle with a convoy of four ships off the coast of New Guinea and destroyed the entire convoy. She was also one of the first U.S. subs into the Sea of Japan. She was sunk while exiting the Sea of Japan through the La Perouse Strait in October 1943 while on her seventh patrol.

Postwar service
At the end of World War II, the U.S. Navy found itself in an awkward position. The 56 remaining Gato-class submarines, designed to fight an enemy that no longer existed, were largely obsolete, despite the fact they were only two to four years old. Such was the pace of technological development during the war that a submarine with only a 300-foot test depth was going to be of little use, despite being modern in most other aspects. Enough of the Balao and Tench ships, with their greater diving depth, remained that the Gatos were superfluous for front-line missions. The Greater Underwater Propulsion Power Program (GUPPY) modernization program of the late 1940s largely passed these ships by. Only USS Barb (SS-220) and USS Dace (SS-247) received GUPPY conversions; these were austere GUPPY IB modernizations under project SCB 47A prior to their transfer to the Italian Navy. However, the U.S. Navy found itself new missions to perform, and for some of these the Gatos were well suited. The last two Gato-class ships active in the U.S. Navy were USS Rock (SS-274) and USS Bashaw (SS-241), which were both decommissioned on 13 September 1969 and sold for scrap.

Radar picket
The advent of the kamikaze demonstrated the need for a long-range radar umbrella around the fleet. Surface ships refitted with powerful radar suites were put into service, but they proved vulnerable in this role, as they could be attacked as well, leaving the fleet blind. A submarine, though, could dive and escape aerial attack. Two Gato-class ships (USS Grouper (SS-214) and USS Finback (SS-230)) received rudimentary conversions to radar pickets before the end of World War II, but were not used in this role. After further experimenting with the concept on four Balao and Tench-class boats under Projects Migraine I and II, and realizing that a deep diving depth was not overly important in this role, six Gatos were taken in hand (USS Pompon (SS-267), USS Rasher (SS-269), USS Raton (SS-270), USS Ray (SS-271), USS Redfin (SS-272), and USS Rock (SS-274)) for conversion under Project Migraine III (aka SCB 12A). They were lengthened by 24 ft to provide additional space for an air control center and had powerful air-search and height-finding radars installed, with the after torpedo room converted into an electronics space with torpedoes and tubes removed. They also received a streamlined "sail" in place of the traditional conning tower fairwater. Redesignated as SSRs, these ships were only moderately successful in this role, as the radars themselves proved troublesome and somewhat unreliable. The radars were removed and the ships temporarily reverted to general-purpose submarines after 1959.

Hunter-killer
The threat of the Soviet Navy building hundreds of Type XXI-derived submarines (eventually the 215-strong Whiskey-class submarine and dozens of others) in the Atlantic led the U.S. Navy to adapt submarines to specifically hunt other submarines, a radically new role for the 1950s. Concluding that this role did not require a fast or deep-diving submarine (this line of thought would quickly change with the advent of nuclear power), seven Gatos were converted to SSKs (hunter-killer submarines) between 1951 and 1953, joining three purpose-built K-1-class SSKs entering service at that time. The Gato class was chosen because large numbers were available in the reserve fleet should rapid mobilization become necessary, and the deeper-diving classes were more suitable for GUPPY rather than SSK conversions. A streamlined GUPPY-style sail was installed, a large sonar array was wrapped around the bow (losing two torpedo tubes in the process), the ships were extensively silenced including the removal of the two forward diesel engines, and they received a snorkel. USS Grouper (SS-214) was converted under project SCB 58 as the test ship for the concept, having her sonar array at the forward end of the sail instead of the better position at the bow. The other ships in the program included USS Angler (SS-240), USS Bashaw (SS-241), USS Bluegill (SS-242), USS Bream (SS-243), USS Cavalla (SS-244), and USS Croaker (SS-246).

Eventually more advanced sonars were installed on the new nuclear subs: USS Tullibee (SSN-597), commissioned in 1960, introduced the bow-mounted sonar sphere. Tullibee was an attempt to develop a slow but ultra-quiet nuclear-powered SSK equivalent; no others were built due to her unexpectedly high cost relative to the more capable USS Thresher (SSN-593), and the SSK mission was folded into the regular attack submarine role. The slow and less capable diesel SSKs were decommissioned or reassigned to other roles in 1959, and all except Croaker and Cavalla (eventually preserved as memorials) were scrapped in 1968 and 1969.

Guided-missile submarine
The Regulus nuclear cruise missile program of the 1950s provided the U.S. Navy with its first strategic missile capability. USS Tunny (SS-282) was converted under SCB 28 in 1953 to house and fire this large surface-launched missile and was designated SSG (guided-missile submarine). She could carry two of the missiles in a cylindrical hangar on the aft deck. She made strategic deterrent patrols with Regulus until 1964, when the program was discontinued in favor of Polaris.

Transport submarine
With the retirement of the Regulus missile system in 1965, USS Tunny (SS-282) was converted into a troop transport in 1966. She was redesignated as an APSS (transport submarine), replacing USS Perch (SS-313) in this role. Her Regulus hangar became a lockout chamber for UDT, SEAL, and Marine Force Recon teams in the Vietnam War. On 1 January 1969, Tunny's designation was changed to LPSS (amphibious transport submarine); however, she was replaced by USS Grayback (LPSS-574) and decommissioned in June of that year.

Submarine oiler
USS Guavina (SS-362) was converted under SCB 39 to a SSO in 1950 to carry fuel oil, gasoline, and cargo to amphibious beachheads. She received additional "saddle" tanks wrapped around her outer hull to carry these fuels and a streamlined sail. After a few tests, the concept was dropped in 1951 as impractical, and Guavina served in the test role for a few years under the designation AGSS. In 1957, she converted back to the oiler/tanker role and carried the designation AOSS. This time, she experimented with refueling seaplanes at sea, which was potentially important, as refueling the nuclear-capable Martin P6M Seamaster at sea could improve the Navy's strategic strike capabilities. However, this mission, too, was dropped and Guavina was decommissioned.

Sonar test submarine
The development of advanced sonar systems took on a great deal of importance in the 1950s, and several fleet ships were outfitted with various strange-looking sonar transducer arrays and performed extensive tests. Two Gatos, USS Flying Fish (SS-229) and USS Grouper (SS-214) (previously the prototype hunter-killer ship) were assigned to these duties and proved to be key players in the development of new sonar capabilities. Grouper had all her forward torpedo tubes removed and the space was used as berthing for technicians and as a sonar lab. Flying Fish was decommissioned in 1954, but Grouper continued in the test role until 1968.

Naval Reserve trainer
Interested in maintaining a ready pool of trained reservists, the Navy assigned numerous fleet ships to various coastal and inland ports (even in Great Lakes ports such as Chicago, Cleveland, and Detroit) where they served as a training platform during the reservists' weekend drills. Twenty-eight Gato-class ships served in this capacity, some as late as 1971. In this role, the ships were rendered incapable of diving and had their propellers removed. They were used strictly as pierside trainers. These were in commission, but classed as "in commission in reserve", thus some were decommissioned and recommissioned on the same day to reflect the change in status.

Foreign service
The large numbers of relatively modern, but surplus U.S. fleet submarines proved to be popular in sales, loans, or leases to allied foreign navies. While most of these ships were of the more capable Balao and Tench classes, some Gatos went overseas, as well. Italy received two (USS Barb (SS-220) and USS Dace (SS-247)), which received the only GUPPY conversions given to Gato-class ships (Guppy IB). Japan received one (USS Mingo (SS-261)), Brazil two (USS Muskallunge (SS-262) and USS Paddle (SS-263)), Greece two (USS Lapon (SS-260) and USS Jack (SS-259)), and Turkey two (USS Guitarro (SS-363) and USS Hammerhead (SS-364)). The ships transferred to Japan and Brazil did not receive any modernizations (streamlining and snorkels) prior to transfer, but the four ships sent to Greece and Turkey did receive snorkels and partial streamlining to the fairwater.

Museums
Six Gato-class submarines are open to public viewing. They primarily depend on revenue generated by visitors to keep them operational and up to U.S. Navy standards; each ship gets a yearly inspection and a "report card". Some ships, such as Cod and Silversides, have been used in film production.

Surviving ships
The following is a complete list of Gato-class museum ships:

 * USS Cavalla (SS-244) is on display at Seawolf Park in Pelican Island, Texas. (in SSK configuration).
 * USS Cobia (SS-245) is on display the Wisconsin Maritime Museum in Manitowoc, Wisconsin.
 * USS Cod (SS-224) is on display at Cleveland's North Coast Harbor in Cleveland, Ohio.
 * USS Croaker (SS-246) is on display at the Buffalo and Erie County Naval & Military Park in Buffalo, New York (in SSK configuration)
 * USS Drum (SS-228) is on display on shore at Battleship Memorial Park in Mobile, Alabama.
 * USS Silversides (SS-236) is on display at the USS Silversides Submarine Museum in Muskegon, Michigan.

title: Gato-class submarine


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Game engine

A game engine is a software framework primarily designed for the development of video games and generally includes relevant libraries and support programs such as a level editor. The "engine" terminology is akin to the term "software engine" used more widely in the software industry.

Game engine can also refer to the development software supporting this framework, typically a suite of tools and features for developing games.

Developers can use game engines to construct games for video game consoles and other types of computers. The core functionality typically provided by a game engine may include a rendering engine ("renderer") for 2D or 3D graphics, a physics engine or collision detection (and collision response), sound, scripting, animation, artificial intelligence, networking, streaming, memory management, threading, localization support, scene graph, and video support for cinematics. Game engine implementers often economize on the process of game development by reusing/adapting, in large part, the same game engine to produce different games or to aid in porting games to multiple platforms.

Purpose

In many cases, game engines provide a suite of visual development tools in addition to reusable software components. These tools are generally provided in an integrated development environment to enable simplified, rapid development of games in a data-driven manner. Game-engine developers often attempt to preempt implementer needs by developing robust software suites which include many elements a game developer may need to build a game. Most game-engine suites provide facilities that ease development, such as graphics, sound, physics and artificial-intelligence (AI) functions. These game engines are sometimes called "middleware" because, as with the business sense of the term, they provide a flexible and reusable software platform which provides all the core functionality needed, right out of the box, to develop a game application while reducing costs, complexities, and time-to-market—all critical factors in the highly competitive video-game industry.

Like other types of middleware, game engines usually provide platform abstraction, allowing the same game to run on various platforms (including game consoles and personal computers) with few, if any, changes made to the game source-code. Often, programmers design game engines with a component-based architecture that allows specific systems in the engine to be replaced or extended with more specialized (and often more expensive) game-middleware components. Some game engines comprise a series of loosely connected game middleware components that can be selectively combined to create a custom engine, instead of the more common approach of extending or customizing a flexible integrated product. However achieved, extensibility remains a high priority for game engines due to the wide variety of uses for which they are applied. Despite the specificity of the name "game engine", end-users often re-purpose game engines for other kinds of interactive applications with real-time graphical requirements—such as marketing demos, architectural visualizations, training simulations, and modeling environments.

Some game engines only provide real-time 3D rendering capabilities instead of the wide range of functionality needed by games. These engines rely upon the game developer to implement the rest of this functionality or to assemble it from other game-middleware components. These types of engines are generally referred to as a "graphics engine", "rendering engine", or "3D engine" instead of the more encompassing term "game engine". This terminology is inconsistently used, as many full-featured 3D game engines are referred to simply as "3D engines". Examples of graphics engines include: Crystal Space, Genesis3D, Irrlicht, OGRE, RealmForge, Truevision3D, and Vision Engine. Modern game- or graphics-engines generally provide a scene graph—an object-oriented representation of the 3D game-world which often simplifies game design and can be used for more efficient rendering of vast virtual worlds. Most game engines or graphics engines use a Graphics API, which lets you easily communicate with the GPU. But older games did not have hardware acceleration or GPUs and had to build their own software renderer.

As technology ages, the components of an engine may become outdated or insufficient for the requirements of a given project. Since the complexity of programming an entirely new engine may result in unwanted delays (or necessitate that a project restart from the beginning), an engine-development team may elect to update their existing engine with newer functionality or components.

History
Before game engines, games were typically written as singular entities: a game for the Atari 2600, for example, had to be designed from the bottom up to make optimal use of the display hardware—this core display routine is today called the kernel by developers of games for older systems. Other platforms had more leeway, but even when the display was not a concern, memory constraints usually sabotaged attempts to create the data-heavy design that an engine needs. Even on more accommodating platforms, very little could be reused between games. The rapid advance of arcade hardware—which was the leading edge of the market at the time—meant that most of the code would have to be thrown out afterwards anyway, as later generations of games would use completely different game designs that took advantage of extra resources. Thus most game designs through the 1980s were designed through a hard-coded rule set with a small number of levels and graphics data. Since the golden age of arcade video games, it became common for video game companies to develop in-house game engines for use with first-party software.

A notable example of an in-house game engine on home consoles in the mid-1980s was the smooth side-scrolling engine developed by Shigeru Miyamoto's team at Nintendo for the Nintendo Entertainment System (NES). The engine they had developed for the side-scrolling racing game Excitebike (1984) was later employed for the scrolling platformer Super Mario Bros. (1985). This had the effect of allowing Mario to smoothly accelerate from a walk to a run, rather than move at a constant speed like in earlier platformers.

While third-party game engines were not common up until the rise of 3D computer graphics in the 1990s, there were several 2D game creation systems produced in the 1980s for independent video game development. These include Pinball Construction Set (1983), ASCII's War Game Construction Kit (1983), Thunder Force Construction (1984), Adventure Construction Set (1984), Garry Kitchen's GameMaker (1985), Wargame Construction Set (1986), Shoot-'Em-Up Construction Kit (1987), Arcade Game Construction Kit (1988), and most popularly ASCII's RPG Maker engines from 1998 onward. Klik & Play (1994) is another legacy offering that is still available.

The term "game engine" arose in the mid-1990s, especially in connection with 3D games such as first-person shooters with a first-person shooter engine. Epic games, founded by developer Tim Sweeney, debuted Unreal Engine in the year 1998.

Such was the popularity of Id Software's Doom and Quake games that, rather than work from scratch, other developers licensed the core portions of the software and designed their own graphics, characters, weapons and levels—the "game content" or "game assets". Separation of game-specific rules and data from basic concepts like collision detection and game entity meant that teams could grow and specialize.

Later games, such as id Software's Quake III Arena and Epic Games's 1998 Unreal were designed with this approach in mind, with the engine and content developed separately. The practice of licensing such technology has proved to be a useful auxiliary revenue stream for some game developers, as one license for a high-end commercial game engine can range from US$10,000 to millions of dollars, and the number of licensees can reach several dozen companies, as seen with the Unreal Engine. At the very least, reusable engines make developing game sequels faster and easier, which is a valuable advantage in the competitive video game industry. While there was a strong rivalry between Epic and id around 2000, since then Epic's Unreal Engine has been far more popular than id Tech 4 and its successor id Tech 5.

Modern game engines are some of the most complex applications written, often featuring dozens of finely tuned systems interacting to ensure a precisely controlled user experience. The continued evolution of game engines has created a strong separation between rendering, scripting, artwork, and level design. It is now common, for example, for a typical game development team to have several times as many artists as actual programmers.

First-person shooter games remain the predominant users of third-party game engines, but they are now also being used in other genres. For example, the role-playing video game The Elder Scrolls III: Morrowind and the MMORPG Dark Age of Camelot are based on the Gamebryo engine, and the MMORPG Lineage II is based on the Unreal Engine. Game engines are used for games originally developed for home consoles as well; for example, the RenderWare engine is used in the Grand Theft Auto and Burnout franchises.

Threading is taking on more importance due to modern multi-core systems (e.g. Cell) and increased demands in realism. Typical threads involve rendering, streaming, audio, and physics. Racing games have typically been at the forefront of threading with the physics engine running in a separate thread long before other core subsystems were moved, partly because rendering and related tasks need updating at only 30–60 Hz. For example, on PlayStation 3, physics ran in Need For Speed at 100 Hz versus Forza Motorsport 2 at 360 Hz.

Although the term was first used in the 1990s, there are a few earlier systems in the 1980s that are also considered to be game engines, such as Sierra's Adventure Game Interpreter (AGI) and SCI systems, LucasArts' SCUMM system and Incentive Software's Freescape engine (in 1986 ). Unlike most modern game engines, these game engines were never used in any third-party products (except for the SCUMM system which was licensed to and used by Humongous Entertainment).

As game engine technology matures and becomes more user-friendly, the application of game engines has broadened in scope. They are now being used for serious games: visualization, training, medical, and military simulation applications, with the CryEngine being one example. To facilitate this accessibility, new hardware platforms are now being targeted by game engines, including mobile phones (e.g. Android phones, iPhone) and web browsers (e.g. WebGL, Shockwave, Flash, Trinigy's WebVision, Silverlight, Unity Web Player, O3D and pure DHTML).

Additionally, more game engines are being built upon higher level languages such as Java and C#/.NET (e.g. TorqueX, and Visual3D.NET), Python (Panda3D), or Lua Script (Leadwerks). As most 3D rich games are now mostly GPU-limited (i.e. limited by the power of the graphics card), the potential slowdown due to translation overheads of higher level languages becomes negligible, while the productivity gains offered by these languages work to the game engine developers' benefit. These recent trends are being propelled by companies such as Microsoft to support indie game development. Microsoft developed XNA as the SDK of choice for all video games released on Xbox and related products. This includes the Xbox Live Indie Games channel designed specifically for smaller developers who do not have the extensive resources necessary to box games for sale on retail shelves. It is becoming easier and cheaper than ever to develop game engines for platforms that support managed frameworks.

Game engines as an industry
Producers of game engines decide how they allow users to utilize their products. Just as gaming is an industry, so are the engines they are built off. The major game engines come at varying prices, whether it be in the form of subscription fees or license payments. Unity and the Unreal Engine are currently the two most popular choices for game developers. Although the differences among the different game engines blur as they build their own tools on top of them, different game developers may be too used to a system to change, or attracted by the huge benefits of such engines regardless of pay-walls.

Game middleware
In the broader sense of the term, game engines themselves can be described as middleware. In the context of video games, however, the term "middleware" is often used to refer to subsystems of functionality within a game engine. Some game middleware does only one thing but does it more convincingly or more efficiently than general purpose middleware.

The four most widely used middleware packages that provide subsystems of functionality include RAD Game Tools' Bink, Firelight FMOD, Havok, and Scaleform GFx. RAD Game Tools develops Bink for basic video rendering, along with Miles audio, and Granny 3D rendering. Firelight FMOD is a low cost robust audio library and toolset. Havok provides a robust physics simulation system, along with a suite of animation and behavior applications. Scaleform provides GFx for high performance Flash UI and high-quality video playback, and an Input Method Editor (IME) add-on for in-game Asian chat support.

Other middleware is used for performance optimisation—for example 'Simplygon' helps to optimise and generate level of detail meshes, and 'Umbra' adds occlusion culling optimisations to 3d graphics.

Some middleware contains full source code, others just provide an API reference for a compiled binary library. Some middleware programs can be licensed either way, usually for a higher fee for full source code.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Game engine


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Talk:Schneider Trophy

poorly done opening paragraph.
opening with '(sometimes incorrectly referred to as the Schneider Cup, a different prize)' pretty much requires giving some indication of what the other prize is. though that might be complicated, as the 'Schneider Cup' page is just a redirect to the 'Schneider Trophy' page. i spent a few minutes searching for the Schneider Cup, but did not find anything informative. i did find that the wiki pages for a few Schneider Trophy winners called it [apparently incorrectly] the Schneider Cup. so some cleanup is in order here, but since i don't know what the Schneider Cup is, i can't do it myself. 2600:8801:8500:D72:A89C:FD47:1C58:F490 (talk) 04:50, 10 October 2020 (UTC)

 * I agree and have seen this before. It took some research but I've got the answer. mention of this 'other' Schneider Cup was actually bolded and in the lead slightly below. It is incorrect to say the Schneider Trophy is not sometimes called the Schneider Cup as it very clearly is in many sources and Coupe is cup in French!

 * The physically different piece of silverware was awarded by Jacques Schneider to Bertram Dickson in 1910 after winning a land based event in France. The trophy was presented to the RAF College Cranwell in 1946 by his sister, it is photographed and captioned on their Facebook page. A very good account of this event and a photo of the trophy itself are recorded here.

 * I have amended the text in this article but ideally we need a reliably sourced article on this event to clearly separate the two. Nimbus (Cumulus nimbus floats by)  09:50, 10 October 2020 (UTC)

title: Talk:Schneider Trophy


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Poverty threshold

The poverty threshold, poverty limit, poverty line, or breadline is the minimum level of income deemed adequate in a particular country. The poverty line is usually calculated by estimating the total cost of one year's worth of necessities for the average adult. The cost of housing, such as the rent for an apartment, usually makes up the largest proportion of this estimate, so economists track the real estate market and other housing cost indicators as a major influence on the poverty line. Individual factors are often used to account for various circumstances, such as whether one is a parent, elderly, a child, married, etc. The poverty threshold may be adjusted annually. In practice, like the definition of poverty, the official or common understanding of the poverty line is significantly higher in developed countries than in developing countries.

In September 2022, the World Bank updated the International Poverty Line (IPL), a global absolute minimum, to $2.15 per day (in PPP). In addition, as of 2022, $3.65 per day in PPP for lower-middle income countries, and $6.85 per day in PPP for upper-middle income countries. Per the $1.90/day standard, the percentage of the global population living in absolute poverty fell from over 80% in 1800 to 10% by 2015, according to United Nations estimates, which found roughly 734 million people remained in absolute poverty.

History
Charles Booth, a pioneering investigator of poverty in London at the turn of the 20th century, popularised the idea of a poverty line, a concept originally conceived by the London School Board. Booth set the line at 10 (50p) to 20 shillings (£1) per week, which he considered to be the minimum amount necessary for a family of four or five people to subsist on. Seebohm Rowntree (1871–1954), a British sociological researcher, social reformer and industrialist, surveyed rich families in York, and drew a poverty line in terms of a minimum weekly sum of money "necessary to enable families … to secure the necessaries of a healthy life", which included fuel and light, rent, food, clothing, and household and personal items. Based on data from leading nutritionists of the period, he calculated the cheapest price for the minimum calorific intake and nutritional balance necessary, before people get ill or lose weight. He considered this amount to set his poverty line and concluded that 27.84% of the total population of York lived below this poverty line. This result corresponded with that from Booth's study of poverty in London and so challenged the view, commonly held at the time, that abject poverty was a problem particular to London and was not widespread in the rest of Britain. Rowntree distinguished between primary poverty, those lacking in income and secondary poverty, those who had enough income, but spent it elsewhere (1901:295–96).

The poverty threshold was first developed by Mollie Orshansky between 1963 and 1964. She attributed the poverty threshold as a measure of income inadequacy by taking the cost of food plan per family of three or four and multiplying it by a factor of three. In 1969 the inter agency poverty level review committee adjusted the threshold for only price changes.

Absolute poverty and the International Poverty Line
The term "absolute poverty" is also sometimes used as a synonym for extreme poverty. Absolute poverty is the absence of enough resources to secure basic life necessities. To assist in measuring this, the World Bank has a daily per capita international poverty line (IPL), a global absolute minimum, of $2.15 a day as of September 2022.

The new IPL replaces the $1.25 per day figure, which used 2005 data. In 2008, the World Bank came out with a figure (revised largely due to inflation) of $1.25 a day at 2005 purchasing power parity (PPP). The new figure of $1.90 is based on ICP PPP calculations and represents the international equivalent of what $1.90 could buy in the US in 2011. Most scholars agree that it better reflects today's reality, particularly new price levels in developing countries. The common IPL has in the past been roughly $1 a day.

These figures are artificially low according to Peter Edward of Newcastle University. He believes the real number as of 2015 was $7.40 per day.

Using a single monetary poverty threshold is problematic when applied worldwide, due to the difficulty of comparing prices between countries. Prices of the same goods vary dramatically from country to country; while this is typically corrected for by using PPP exchange rates, the basket of goods used to determine such rates is usually unrepresentative of the poor, most of whose expenditure is on basic foodstuffs rather than the relatively luxurious items (washing machines, air travel, healthcare) often included in PPP baskets. The economist Robert C. Allen has attempted to solve this by using standardized baskets of goods typical of those bought by the poor across countries and historical time, for example including a fixed calorific quantity of the cheapest local grain (such as corn, rice, or oats).

Basic needs
The basic needs approach is one of the major approaches to the measurement of poverty in developing countries. It attempts to define the absolute minimum resources necessary for long-term physical well-being, usually in terms of consumption goods. The poverty line is then defined as the amount of income required to satisfy those needs. The 'basic needs' approach was introduced by the International Labour Organization's World Employment Conference in 1976. "Perhaps the high point of the WEP was the World Employment Conference of 1976, which proposed the satisfaction of basic human needs as the overriding objective of national and international development policy. The basic needs approach to development was endorsed by governments and workers' and employers' organizations from all over the world. It influenced the programs and policies of major multilateral and bilateral development agencies, and was the precursor to the human development approach."

A traditional list of immediate "basic needs" is food (including water), shelter, and clothing. Many modern lists emphasize the minimum level of consumption of 'basic needs' of not just food, water, and shelter, but also sanitation, education, and health care. Different agencies use different lists. According to a UN declaration that resulted from the World Summit on Social Development in Copenhagen in 1995, absolute poverty is "a condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education, and information. It depends not only on income, but also on access to services."

David Gordon's paper, "Indicators of Poverty and Hunger", for the United Nations, further defines absolute poverty as the absence of any two of the following eight basic needs:
 * Food: Body mass index must be above 16.
 * Safe drinking water: Water must not come solely from rivers and ponds, and must be available nearby (fewer than 15 minutes' walk each way).
 * Sanitation facilities: Toilets or latrines must be accessible in or near the home.
 * Health: Treatment must be received for serious illnesses and pregnancy.
 * Shelter: Homes must have fewer than four people living in each room. Floors must not be made of soil, mud, or clay.
 * Education: Everyone must attend school or otherwise learn to read.
 * Information: Everyone must have access to newspapers, radios, televisions, computers, or telephones at home.
 * Access to services: This item is undefined by Gordon, but normally is used to indicate the complete panoply of education, health, legal, social, and financial (credit) services.

In 1978, Ghai investigated the literature that criticized the basic needs approach. Critics argued that the basic needs approach lacked scientific rigour; it was consumption-oriented and antigrowth. Some considered it to be "a recipe for perpetuating economic backwardness" and for giving the impression "that poverty elimination is all too easy". Amartya Sen focused on 'capabilities' rather than consumption.

In the development discourse, the basic needs model focuses on the measurement of what is believed to be an eradicable level of poverty.

Relative poverty
Relative poverty means low income relative to others in a country: for example, below 60% of the median income of people in that country.

Relative poverty measurements unlike absolute poverty measurements take the social economic environment of the people observed into consideration. It is based on the assumption that whether a person is considered poor depends on her/his income share relative to the income shares of other people who are living in the same economy. The threshold for relative poverty is considered to be at 50% of a country's median equivalised disposable income after social transfers. Thus, it can vary greatly from country to country even after adjusting for purchasing power standards (PPS).

A person can be poor in relative terms but not in absolute terms as the person might be able to meet her/his basic needs, but not be able to enjoy the same standards of living that other people in the same economy are enjoying. Relative poverty is thus a form of social exclusion that can for example affect peoples access to decent housing, education or job opportunities.

The relative poverty measure is used by the United Nations Development Program (UNDP), the United Nations Children's Fund (UNICEF), the Organisation for Economic Co-operation and Development (OECD) and Canadian poverty researchers. In the European Union, the "relative poverty measure is the most prominent and most–quoted of the EU social inclusion indicators."

"Relative poverty reflects better the cost of social inclusion and equality of opportunity in a specific time and space."

"Once economic development has progressed beyond a certain minimum level, the rub of the poverty problem – from the point of view of both the poor individual and of the societies in which they live – is not so much the effects of poverty in any absolute form but the effects of the contrast, daily perceived, between the lives of the poor and the lives of those around them. For practical purposes, the problem of poverty in the industrialized nations today is a problem of relative poverty (page 9)."

However, some have argued that as relative poverty is merely a measure of inequality, using the term 'poverty' for it is misleading. For example, if everyone in a country's income doubled, it would not reduce the amount of 'relative poverty' at all.

History of the concept of relative poverty
In 1776, Adam Smith argued that poverty is the inability to afford "not only the commodities which are indispensably necessary for the support of life, but whatever the custom of the country renders it indecent for creditable people, even of the lowest order, to be without."

In 1958, John Kenneth Galbraith argued, "People are poverty stricken when their income, even if adequate for survival, falls markedly behind that of their community."

In 1964, in a joint committee economic President's report in the United States, Republicans endorsed the concept of relative poverty: "No objective definition of poverty exists. ... The definition varies from place to place and time to time. In America as our standard of living rises, so does our idea of what is substandard."

In 1965, Rose Friedman argued for the use of relative poverty claiming that the definition of poverty changes with general living standards. Those labelled as poor in 1995, would have had "a higher standard of living than many labelled not poor" in 1965.

In 1967, American economist Victor Fuchs proposed that "we define as poor any family whose income is less than one-half the median family income." This was the first introduction of the relative poverty rate as typically computed today

In 1979, British sociologist, Peter Townsend published his famous definition: "individuals... can be said to be in poverty when they lack the resources to obtain the types of diet, participate in the activities and have the living conditions and amenities which are customary, or are at least widely encouraged or approved, in the societies to which they belong (page 31)."

Brian Nolan and Christopher T. Whelan of the Economic and Social Research Institute (ESRI) in Ireland explained that "poverty has to be seen in terms of the standard of living of the society in question."

Relative poverty measures are used as official poverty rates by the European Union, UNICEF and the OECD. The main poverty line used in the OECD and the European Union is based on "economic distance", a level of income set at 60% of the median household income.

Relative poverty compared with other standards
A measure of relative poverty defines "poverty" as being below some relative poverty threshold. For example, the statement that "those individuals who are employed and whose household equivalised disposable income is below 60% of national median equivalised income are poor" uses a relative measure to define poverty.

The term relative poverty can also be used in a different sense to mean "moderate poverty" – for example, a standard of living or level of income that is high enough to satisfy basic needs (like water, food, clothing, housing, and basic health care), but still significantly lower than that of the majority of the population under consideration. An example of this could be a person living in poor conditions or squalid housing in a high crime area of a developed country and struggling to pay their bills every month due to low wages, debt or unemployment. While this person still benefits from the infrastructure of the developed country, they still endure a less than ideal lifestyle compared to their more affluent countrymen or even the more affluent individuals in less developed countries who have lower living costs.

Living Income Concept
Living Income refers to the income needed to afford a decent standard of living in the place one lives. The distinguishing feature between a living income and the poverty line is the concept of decency, wherein people thrive, not only survive. Based on years of stakeholder dialogue and expert consultations, the Living Income Community of Practice, an open learning community, established the formal definition of living income drawing on the work of Richard and Martha Anker, who co-authored "Living Wages Around the World: Manual for Measurement". They define a living income as: "The net annual income required for a household in a particular place to afford a decent standard of living for all members of that household. Elements of a decent standard of living include food, water, housing, education, healthcare, transport, clothing, and other essential needs including provision for unexpected events."Like the poverty line calculation, using a single global monetary calculation for Living Income is problematic when applied worldwide. Additionally, the Living Income should be adjusted quarterly due to inflation and other significant changes such as currency adjustments. The actual income or proxy income can be used when measuring the gap between initial income and the living income benchmarks. The World Bank notes that poverty and standard of living can be measured by social perception as well, and found that in 2015, roughly one-third of the world's population was considered poor in relation to their particular society.

The Living Income Community of Practice (LICOP) was founded by The Sustainable Food Lab, GIZ and ISEAL Alliance to measure the gap between what people around the world earn versus what they need to have a decent standard of living, and find ways to bridge this gap.

A variation on the LICOP's Living Income is the Massachusetts Institute of Technology's Living Wage Calculator, which compares the local minimum wage to the amount of money needed to cover expenses beyond what is needed to merely survive across the United States. The cost of living varies greatly if there are children or other dependents in the household.

Relevance
An outdated or flawed poverty measure is an obstacle for policymakers, researchers and academics trying to find solutions to the problem of poverty. This has implications for people. The federal poverty line is used by dozens of federal, state, and local agencies, as well as several private organizations and charities, to decide who needs assistance. The assistance can take many forms, but it is often difficult to put in place any type of aid without measurements which provide data. In a rapidly evolving economic climate, poverty assessment often aids developed countries in determining the efficacy of their programs and guiding their development strategy. In addition, by measuring poverty one receives knowledge of which poverty reduction strategies work and which do not, helping to evaluate different projects, policies and institutions. To a large extent, measuring the poor and having strategies to do so keep the poor on the agenda, making the problem of political and moral concern.

Threshold limitations
It is hard to have exact number for poverty, as much data is collected through interviews, meaning income that is reported to the interviewer must be taken at face value. As a result, data could not rightly represent the situations true nature, nor fully represent the income earned illegally. In addition, if the data were correct and accurate, it would still not mean serving as an adequate measure of the living standards, the well-being or economic position of a given family or household. Research done by Haughton and Khandker finds that there is no ideal measure of well-being, arguing that all measures of poverty are imperfect. That is not to say that measuring poverty should be avoided; rather, all indicators of poverty should be approached with caution, and questions about how they are formulated should be raised.

As a result, depending on the indicator of economic status used, an estimate of who is disadvantaged, which groups have the highest poverty rates, and the nation's progress against poverty varies significantly. Hence, this can mean that defining poverty is not just a matter of measuring things accurately, but it also necessitates fundamental social judgments, many of which have moral implications.

National poverty lines
National estimates are based on population-weighted subgroup estimates from household surveys. Definitions of the poverty line do vary considerably among nations. For example, rich nations generally employ more generous standards of poverty than poor nations. Even among rich nations, the standards differ greatly. Thus, the numbers are not comparable among countries. Even when nations do use the same method, some issues may remain.

United Kingdom
In the UK in 2006, "more than five million people – over a fifth (23 percent) of all employees – were paid less than £6.67 an hour". This value is based on a low pay rate of 60 percent of full-time median earnings, equivalent to a little over £12,000 a year for a 35-hour working week. In April 2006, a 35-hour week would have earned someone £9,191 a year – before tax or National Insurance".

In 2019, the Low Pay Commission estimated that about 7% of people employed in the UK were earning at or below the National Minimum Wage. In 2021, the Office for National Statistics found that 3.8% of jobs were paid below the National Minimum Wage, a decrease from 7.4% in 2020 but an increase from 1.4% in 2019. They note that this increase from 2019 to 2021 is connected to the COVID-19 pandemic in the United Kingdom. The Guardian reported in 2021 that "almost 5m jobs, or one in six nationally, pay below the real living wage".

India
India's official poverty level is split according to rural versus urban thresholds. For urban dwellers, the poverty line is defined as living on less than 538.60 rupees (approximately US$12) per month, whereas for rural dwellers, it is defined as living on less than 356.35 rupees per month (approximately US$7.50) In 2019, the Indian government stated that 6.7% of its population is below its official poverty limit. As India is one of the fastest-growing economies in 2018, poverty is on the decline in the country, with close to 44 Indians escaping extreme poverty every minute, as per the World Poverty Clock. India lifted 271 million people out of poverty in a 10-year time period from 2005/06 to 2015/16.

Iran
In 2008 Iran government report by central statistics had recommended 9.5 around million people living below poverty line. As of August 2022 the Iranian economy suffered the highest inflation in 75 years; official statistics put the poverty line at 10 million tomans ($500), while the minimum wage given in the same year has been 5 million toman.

Singapore
Singapore has experienced strong economic growth over the last ten years and has consistently ranked among the world's top countries in terms of GDP per capita.

Inequality has however increased dramatically over the same time span, yet there is no official poverty line in the country. Given Singapore's high level of growth and prosperity, many believe that poverty does not exist in the country, or that domestic poverty is not comparable to global absolute poverty. Such a view persists for a selection of reasons, and since there is no official poverty line, there is no strong acknowledgement that it exists.

Yet, Singapore is not considering establishing an official poverty line, with Minister for Social and Family Development Chan Chun Sing claiming it would fail to represent the magnitude and scope of problems faced by the poor. As a result, social benefits and aids aimed at the poor would be a missed opportunity for those living right above such a line.

United States
In the United States, the poverty thresholds are updated every year by Census Bureau. The threshold in the United States is updated and used for statistical purposes. In 2020, in the United States, the poverty threshold for a single person under 65 was an annual income of US$12,760, or about $35 per day. The threshold for a family group of four, including two children, was US$26,200, about $72 per day. According to the US Census Bureau's American Community Survey 2018 One-year Estimates, 13.1% of Americans lived below the poverty line.

Women and children
Women and children find themselves impacted by poverty more often when a part of single mother families. The poverty rate of women has increasingly exceeded that of men's. While the overall poverty rate is 12.3%, women poverty rate is 13.8% which is above the average and men are below the overall rate at 11.1%. Women and children (as single mother families) find themselves as a part of low class communities because they are 21.6% more likely to fall into poverty. However, extreme poverty, such as homelessness, disproportionately affects males to a high degree.

Racial minorities
A minority group is defined as "a category of people who experience relative disadvantage as compared to members of a dominant social group." Minorities are traditionally separated into the following groups: African Americans, American Indians, Alaska Natives, Asians, Pacific Islanders, and Hispanics. According to the current US Poverty statistics, Black Americans – 21%, Foreign born non-citizens – 19%, Hispanic Americans – 18%, and adults with a disability – 25%. This does not include all minority groups, but these groups alone account for 85% of people under the poverty line in the United States. Whites have a poverty rate of 8.7%; the poverty rate is more than double for Black and Hispanic Americans.

Impacts on education
Living below the poverty threshold can have a major impact on a child's education. The psychological stresses induced by poverty may affect a student's ability to perform well academically. In addition, the risk of poor health is more prevalent for those living in poverty. Health issues commonly affect the extent to which one can continue and fully take advantage of his or her education. Poor students in the United States are more likely to dropout of school at some point in their education. Research has also found that children living in poverty perform poorly academically and have lower graduation rates. Impoverished children also experience more disciplinary issues in school than others.

Schools in impoverished communities usually do not receive much funding, which can also set their students apart from those living in more affluent neighborhoods. There is much dispute over whether upward mobility that brings a child out of poverty may or may not have a significant positive impact on his or her education; inadequate academic habits that form as early as preschool typically are unknown to improve despite changes in socioeconomic status.

Impacts on healthcare
The nation's poverty threshold is issued by the Census Bureau. According to the Office of Assistant Secretary for Planning and Evaluation the threshold is statistically relevant and can be a solid predictor of people in poverty. The reasoning for using Federal Poverty Level (FPL) is due to its action for distributive purposes under the direction of Health and Human Services. So FPL is a tool derived from the threshold but can be used to show eligibility for certain federal programs. Federal poverty levels have direct effects on individuals' healthcare. In the past years and into the present government, the use of the poverty threshold has consequences for such programs like Medicaid and the Children's Health Insurance Program. The benefits which different families are eligible for are contingent on FPL. The FPL, in turn, is calculated based on federal numbers from the previous year.

The benefits and qualifications for federal programs are dependent on number of people on a plan and the income of the total group. For 2019, the U.S. Department of Health & Human Services enumerate what the line is for different families. For a single person, the line is $12,490 and up to $43,430 for a family of 8, in the lower 48 states. Another issue is reduced-cost coverage. These reductions are based on income relative to FPL, and work in connection with public health services such as Medicaid. The divisions of FPL percentages are nominally, above 400%, below 138% and below 100% of the FPL. After the advent of the American Care Act, Medicaid was expanded on states bases. For example, enrolling in the ACA kept the benefits of Medicaid when the income was up to 138% of the FPL.

Poverty mobility and healthcare
Health Affairs along with analysis by Georgetown found that public assistance does counteract poverty threats between 2010 and 2015. In regards to Medicaid, child poverty is decreased by 5.3%, and Hispanic and Black poverty by 6.1% and 4.9% respectively. The reduction of family poverty also has the highest decrease with Medicaid over other public assistance programs. Expanding state Medicaid decreased the amount individuals paid by an average of $42, while it increased the costs to $326 for people not in expanded states. The same study analyzed showed 2.6 million people were kept out of poverty by the effects of Medicaid. From a 2013–2015 study, expansion states showed a smaller gap in health insurance between households making below $25,000 and above $75,000. Expansion also significantly reduced the gap of having a primary care physician between impoverished and higher income individuals. In terms of education level and employment, health insurance differences were also reduced. Non-expansion also showed poor residents went from a 22% chance of being uninsured to 66% from 2013 to 2015.

Poverty dynamics
Living above or below the poverty threshold is not necessarily a position in which an individual remains static. As many as one in three impoverished people were not poor at birth; rather, they descended into poverty over the course of their life. Additionally, a study which analyzed data from the Panel Study of Income Dynamics (PSID) found that nearly 40% of 20-year-olds received food stamps at some point before they turned 65. This indicates that many Americans will dip below the poverty line sometime during adulthood, but will not necessarily remain there for the rest of their life. Furthermore, 44% of individuals who are given transfer benefits (other than Social Security) in one year do not receive them the next. Over 90% of Americans who receive transfers from the government stop receiving them within 10 years, indicating that the population living below the poverty threshold is in flux and does not remain constant.

Cutoff issues
Most experts and the public agree that the official poverty line in the United States is substantially lower than the actual cost of basic needs. In particular, a 2017 Urban Institute study found that 61% of non-elderly adults earning between 100 and 200% of the poverty line reported at least one material hardship, not significantly different from those below the poverty line. The cause of the discrepancy is believed to be an outdated model of spending patterns based on actual spending in the year 1955; the number and proportion of material needs has risen substantially since then.

Variability
The US Census Bureau calculates the poverty line the same throughout the US regardless of the cost-of-living in a state or urban area. For instance, the cost-of-living in California, the most populous state, was 42% greater than the US average in 2010, while the cost-of-living in Texas, the second-most populous state, was 10% less than the US average. In 2017, California had the highest poverty rate in the country when housing costs are factored in, a measure calculated by the Census Bureau known as "the supplemental poverty measure".

Government transfers to alleviate poverty
In addition to wage and salary income, investment income and government transfers such as SNAP (Supplemental Nutrition Assistance Program, also known as food stamps) and housing subsidies are included in a household's income. Studies measuring the differences between income before and after taxes and government transfers, have found that without social support programs, poverty would be roughly 30% to 40% higher than the official poverty line indicates.

title: Poverty threshold