SCB-27, or "Two Seven-Charlie" was the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 designation for a series of upgrades to the Essex

Essex class aircraft carrier

The Essex class was a class of aircraft carriers of the United States Navy, which constituted the 20th century's most numerous class of capital ships with 24 vessels built in both "short-hull" and "long-hull" versions. Thirty-two were originally ordered; however as World War II wound down, six were...

 class aircraft carrier

Aircraft carrier

An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

s (both the short-hull and long-hull (Ticonderoga) versions), conducted between 1947 and 1955. These upgrades were intended to allow the World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

-era carriers to operate jet aircraft

Jet aircraft

A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...

.

Modifications

The SCB-27 modernization was very extensive, requiring some two years for each carrier. To handle the much heavier, faster aircraft of the early jet-era, the flight deck

Flight deck

The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the...

 structure was significantly reinforced, able to support aircraft weighing up to 52000 pounds (23,587 kg), namely the North American AJ Savage

AJ Savage

|-See also:-References:NotesBibliography* Grossnick, Roy A. . Washington, DC:Naval Historical Center, 1995. ISBN 0-945274-29-7.* Swanborough, Gordon and Peter M. Bowers. United States Navy Aircraft since 1911. London:Putnam, Second edition, 1976. ISBN 0 370 10054 9.* Wilson, Stewart. Combat...

. Stronger and larger elevators, much more powerful catapults

Aircraft catapult

An aircraft catapult is a device used to launch aircraft from ships—in particular aircraft carriers—as a form of assisted take off. It consists of a track built into the flight deck, below which is a large piston or shuttle that is attached through the track to the nose gear of the aircraft, or in...

, and new Mk 5 arresting gear

Arresting gear

Arresting gear, or arrestor gear, is the name used for mechanical systems designed to rapidly decelerate an aircraft as it lands. Arresting gear on aircraft carriers is an essential component of naval aviation, and it is most commonly used on CATOBAR and STOBAR aircraft carriers. Similar systems...

 were installed. The original four twin 5"/38 gun mounts were removed, clearing the flight deck of guns. The new five-inch gun battery consisted of eight weapons, two on each quarter beside the flight deck. Twin 3"/50 gun mounts replaced the 40mm guns

Bofors 40 mm gun

The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...

, offering much greater effectiveness through the use of proximity fuze

Proximity fuze

A proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...

d ammunition.

The island was completely redesigned, made taller, but shorter in overall length with the removal of its gun mounts. In addition, the boiler uptakes were rebuilt and angled aft to accommodate a single radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 and communications mast atop the island. To better protect aircrews, ready room

Ready room

A ready room is a room on an aircraft carrier where on-duty pilots "stand by" their aeroplanes. Each flight squadron has its own individual ready room. Large squadrons, such as torpedo and dive-bomber squadrons, can have more than one ready room...

s were moved from the gallery deck to below the armored hangar deck, with a large escalator

Escalator

An escalator is a moving staircase – a conveyor transport device for carrying people between floors of a building. The device consists of a motor-driven chain of individual, linked steps that move up or down on tracks, allowing the step treads to remain horizontal.Escalators are used around the...

 on the starboard side amidships to move flight crews up to the flight deck. Internally, aviation fuel capacity was increased to 300000 gallons (1,135,624 l) (a 50% increase) and its pumping capacity enhanced to 50 gallons (189.3 l) per minute. Fire fighting capabilities were enhanced through the addition of two emergency fire and splinter bulkheads

Bulkhead (partition)

A bulkhead is an upright wall within the hull of a ship or within the fuselage of an airplane. Other kinds of partition elements within a ship are decks and deckheads.-Etymology:...

 to the hangar deck, a fog/foam firefighting system, improved water curtains

Safety curtain

A safety curtain is a fire safety precaution used in large proscenium theatres. It is usually a heavy fibreglass or iron curtain located immediately behind the proscenium arch. Asbestos-based materials were originally used to manufacture the curtain, before the dangers of asbestos were discovered...

 and a cupronickel

Cupronickel

Cupronickel or copper-nickel or "cupernickel" is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Cupronickel is highly resistant to corrosion in seawater, because its electrode potential is adjusted to be neutral with regard to seawater...

 fire main. Also improved were electrical generating power, and weapons stowage and handling facilities. All this added considerable weight: displacement

Displacement (fluid)

In fluid mechanics, displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can then be measured, as in the illustration, and from this the volume of the immersed object can be deduced .An object that sinks...

 increased by some twenty percent. The armor belt was removed and blisters were fitted to the hull sides to compensate, widening waterline beam

Beam (nautical)

The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

 by eight to ten feet. The ships also sat lower in the water, and maximum speed was slightly reduced, to 31 knots.

Modification sub-types

The two sub-types of SCB-27 modifications were primarily a result of changes in catapult technology in the early-1950s. SCB-27A vessels utilized a pair of H 8 slotted-tube hydraulic catapults, while the later SCB-27C vessels were fitted with a pair of C 11 steam catapults, a British

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 innovation. To accommodate the catapult machinery, the SCB-27C vessels were slightly wider abeam and heavier than their SCB-27A sisters. Additionally, the SBC-27C carriers were equipped with jet blast deflector

Jet blast deflector

A jet blast deflector or blast fence is a safety device that redirects the high energy exhaust from a jet engine to prevent damage and injury. The structure must be strong enough to withstand heat and high speed air streams as well as dust and debris carried by the turbulent air...

s, deck cooling, fuel blending facilities, emergency recovery barrier and storage and handling for nuclear weapon

Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s, which was not included in all of the SCB-27A carriers. Under SCB-27C the No. 3 (after) elevator was moved to the starboard deck edge; this elevator was located further aft on the first three SCB-27C ships than it was on the ships which received it concomitantly with an angled flight deck under the SCB-125 program.

Program history

USS Oriskany (CV-34)

USS Oriskany (CV-34)

USS Oriskany – nicknamed Mighty O, The O-boat, and Toasted O – was one of 24 s completed during or shortly after World War II for the United States Navy. The ship was the third US Navy ship to bear the name, and was named for the Revolutionary War Battle of Oriskany.The history of...

, laid-up incomplete at the conclusion of World War II, served as the prototype and was re-ordered to the SCB-27A standard. All of the SCB-27 modernized Essex carriers, save USS Lake Champlain (CV-39)

USS Lake Champlain (CV-39)

USS Lake Champlain was one of 24 s completed during or shortly after World War II for the United States Navy. She was the second US Navy ship to bear the name, and was named for the Battle of Lake Champlain in the War of 1812....

, were further modified, under the SCB-125

SCB-125

SCB-125 was the United States Navy designation for a series of upgrades to the Essex class of aircraft carriers , conducted between 1954 and 1959...

 modernization program.

Modified vessels

Source:www.history.navy.mil

	Program	Shipyard	Work Began	Recommissioned
USS Oriskany (CV-34) USS Oriskany (CV-34) USS Oriskany – nicknamed Mighty O, The O-boat, and Toasted O – was one of 24 s completed during or shortly after World War II for the United States Navy. The ship was the third US Navy ship to bear the name, and was named for the Revolutionary War Battle of Oriskany.The history of...	SCB-27A	New York	Aug 1947	Sep 1950
USS Essex (CV-9) USS Essex (CV-9) USS Essex was an aircraft carrier, the lead ship of the 24-ship built for the United States Navy during World War II. She was the fourth US Navy ship to bear the name. Commissioned in December 1942, Essex participated in several campaigns in the Pacific Theater of Operations, earning the...	SCB-27A	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Feb 1949	Jan 1951
USS Wasp (CV-18) USS Wasp (CV-18) USS Wasp was one of 24 s built during World War II for the United States Navy. The ship, the ninth US Navy ship to bear the name, was originally named Oriskany, but was renamed while under construction in honor of the previous , which was sunk 15 September 1942...	SCB-27A	New York	May 1949	Sep 1951
USS Kearsarge (CV-33) USS Kearsarge (CV-33) USS Kearsarge was one of 24 s completed during or shortly after World War II for the United States Navy. The ship was the third US Navy ship to bear the name, and was named for a Civil War-era steam sloop. Kearsarge was commissioned in March 1946...	SCB-27A	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Feb 1950	Feb 1952
USS Lake Champlain (CV-39) USS Lake Champlain (CV-39) USS Lake Champlain was one of 24 s completed during or shortly after World War II for the United States Navy. She was the second US Navy ship to bear the name, and was named for the Battle of Lake Champlain in the War of 1812....	SCB-27A	Norfolk Norfolk Naval Shipyard The Norfolk Naval Shipyard, often called the Norfolk Navy Yard and abbreviated as NNSY, is a U.S. Navy facility in Portsmouth, Virginia, for building, remodeling, and repairing the Navy's ships. It's the oldest and largest industrial facility that belongs to the U.S. Navy as well as the most...	Aug 1950	Sep 1952
USS Bennington (CV-20) USS Bennington (CV-20) USS Bennington was one of 24 s built during World War II for the United States Navy. The ship was the second US Navy ship to bear the name, and was named for the Revolutionary War Battle of Bennington...	SCB-27A	New York	Dec 1950	Nov 1952
USS Yorktown (CV-10) USS Yorktown (CV-10) USS Yorktown is one of 24 s built during World War II for the United States Navy. She is named after the Battle of Yorktown of the American Revolutionary War, and is the fourth U.S. Navy ship to bear the name...	SCB-27A	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Mar 1951	Feb 1953
USS Randolph (CV-15) USS Randolph (CV-15) USS Randolph was one of 24 s built during World War II for the United States Navy. The second US Navy ship to bear the name, she was named for Peyton Randolph, president of the First Continental Congress. Randolph was commissioned in October 1944, and served in several campaigns in the Pacific...	SCB-27A	Newport News	June 1951	Jul 1953
USS Hornet (CV-12) USS Hornet (CV-12) USS Hornet is a United States Navy aircraft carrier of the Essex class. Construction started in August 1942; she was originally named , but was renamed in honor of the , which was lost in October 1942, becoming the eighth ship to bear the name.Hornet was commissioned in November 1943, and after...	SCB-27A	New York	July 1951	Sep 1953
USS Hancock (CV-19) USS Hancock (CV-19) USS Hancock was one of 24 s built during World War II for the United States Navy. The ship was the fourth US Navy ship to bear the name, and was named for John Hancock, president of the Second Continental Congress and first governor of the Commonwealth of Massachusetts...	SCB-27C	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Dec 1951	Feb 1954
USS Intrepid (CV-11) USS Intrepid (CV-11) USS Intrepid , also known as The Fighting "I", is one of 24 s built during World War II for the United States Navy. She is the fourth US Navy ship to bear the name. Commissioned in August 1943, Intrepid participated in several campaigns in the Pacific Theater of Operations, most notably the Battle...	SCB-27C	Newport News	Apr 1952	Jun 1954
USS Ticonderoga (CV-14) USS Ticonderoga (CV-14) USS Ticonderoga was one of 24 s built during World War II for the United States Navy. The ship was the fourth US Navy ship to bear the name, and was named for historic Fort Ticonderoga, which played a role in the American Revolutionary War...	SCB-27C	New York	Apr 1952	Sep 1954
USS Shangri-La (CV-38) USS Shangri-La (CV-38) USS Shangri-La was one of 24 s completed during or shortly after World War II for the United States Navy.Commissioned in 1944, Shangri-La participated in several campaigns in the Pacific Theater of Operations in World War II, earning two battle stars...	SCB-27C/125	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Oct 1952	Jan 1955
USS Lexington (CV-16) USS Lexington (CV-16) USS Lexington , known as "The Blue Ghost", is one of 24 s built during World War II for the United States Navy. The ship, the fifth US Navy ship to bear the name, is named in honor of the Revolutionary War Battle of Lexington...	SCB-27C/125	Puget Sound Puget Sound Naval Shipyard Puget Sound Naval Shipyard and Intermediate Maintenance Facility is a United States Navy shipyard covering 179 acres on Puget Sound at Bremerton, Washington...	Sep 1953	Aug 1955
USS Bon Homme Richard (CV-31)	SCB-27C/125	Hunters Point San Francisco Naval Shipyard The San Francisco Naval Shipyard was a United States Navy shipyard in San Francisco, California, located on of waterfront at Hunters Point in the southeast corner of the city...	May 1953	Sep 1955