Operation Sailor Hat

Last updated
Operation Sailor Hat
Sailor Hat Shot.jpg
500 short tons (454 t) of TNT (5 x 10 meter, 17 × 34 feet) awaiting detonation at Operation Sailor Hat. The USS Atlanta is visible in the background.
Information
CountryUnited States
Test site
  • Kahoʻolawe, Hawaii
  • San Clemente Island, California
Coordinates 20°30′15″N156°40′44″W / 20.50417°N 156.67889°W / 20.50417; -156.67889
DateNovember 12, 1964 – June 19, 1965
Number of tests5
AgencyBureau of Ships, DASA
ExplosiveTNT, HBX
Configuration
  • Stacked Hemisphere
  • Underwater Charge
Max. yield0.5 kilotons of TNT (2.1 TJ)
Test chronology

Operation Sailor Hat was a series of explosives effects tests, conducted by the United States Navy Bureau of Ships under the sponsorship of the Defense Atomic Support Agency. [1] The tests consisted of two underwater explosions at San Clemente Island, California in 1964 [2] and three surface explosions at Kahoʻolawe, Hawaii in 1965. They were non-nuclear tests employing large quantities of conventional explosives (TNT and HBX) to determine the effects of a nuclear weapon blast on naval vessels, and the first major test of this kind since Operation Crossroads in July 1946.

Contents

Each "Sailor Hat" test at Kahoʻolawe consisted of a dome-stacked 500-short-ton (454 t) charge of TNT high explosive detonated on the shore close to the ships under test. Since a TNT detonation releases energy more slowly than a nuclear explosion, the blast effect at close range was designed to be equivalent to a 1 kiloton of TNT (4.2 TJ) nuclear weapon at greater distance. [3] The main ship used for testing was the former Cleveland-class light cruiser USS Atlanta. In addition, the guided-missile frigates USS England and USS Dale, the guided-missile destroyers USS Cochrane, USS Benjamin Stoddert, and USS Towers, and the Royal Canadian Navy's escort destroyer HMCS Fraser all participated in the trial. [4] These were a mixture of the obsolete, Atlanta having been built during WWII, and the recently constructed Cochrane. The highly complex operation yielded data useful for determining and improving blast resistance of naval ships.

Background

When the Limited Test Ban Treaty came into effect in 1963, it prohibited nuclear testing in the atmosphere and underwater. The Defense Atomic Support Agency turned to alternative methods of generating airblast effects with high explosives. [5] The previous year in 1964, Operation Snowball was a 500-ton HE test on the Experimental Proving Ground in Alberta, Canada that provided technical information related to nuclear weapon detonation. [6] In 1963, DASA called on the Bureau of Ships to conduct a full scale explosives test with conventional chemical explosives and a test site had to be chosen. [1]

Following the Japanese attack on Pearl Harbor, the Territory of Hawaii was placed under martial law and the island of Kahoʻolawe was used as a training ground, fleet bombing, and gunnery range. [7] This made it a natural choice for Operation Sailor Hat, since it also had deep waters close to shore and was only 90 miles (140 km) away from the Pearl Harbor Naval Shipyard in Honolulu that could provide industrial support. [1]

Preparations

USS Atlanta at the Hunters' Point Naval Shipyard, San Francisco, California, circa October 1964, while completing conversion to a weapons effects test ship Photo NH 98882 USS Atlanta (IX-304).jpg
USS Atlanta at the Hunters' Point Naval Shipyard, San Francisco, California, circa October 1964, while completing conversion to a weapons effects test ship

A test platform was needed for the operation that could mount a variety of equipment and structures. The light cruiser USS Atlanta was decommissioned in 1949 and placed in the Pacific Reserve Fleet, then in 1962 earmarked for disposal. However, after undergoing extensive modifications at San Francisco Naval Shipyard she was converted to a target ship (reinstated as IX-304) to study the effects of high energy air explosions. The hull was cut down to the main deck level and two different types of destroyer deckhouses and three mast arrays were fitted. [8] [1] Representative destroyer systems for communication, detection, fire control and weapons delivery were installed and an experimental reinforced fiberglass deckhouse was constructed for comparison with aluminum ones used at the time. It was noted that in such an unusual configuration the refitted Atlanta received many stares and comments while en route to the test site in Hawaii. [1]

The preparation of the charges was in itself an engineering feat. The TNT was supplied by the Naval Powder Factory in Hawthorne, NV that developed a method of producing high quality cast blocks from materials recovered from old torpedoes, mines and other weapons. A total of 92,022 4 by 12 by 12 inches (101.6 mm × 304.8 mm × 304.8 mm) blocks were produced for the tests. The Navy Construction Battalion Three had the hazardous task of carefully assembling 30,674 32.98-pound (14.96 kg) TNT blocks into 34-foot (10 m) hemispheres that reached a height of 17 feet (5.2 m) for each of the three tests. The domes were placed on thin octagonal concrete pads close to shore. In order to obtain the desired results, the ships also needed to be moored at precise distances from the charge for each test. This proved a difficult task in high winds and was accomplished with help from the Bureau of Ships, the tug USS Sunnadin (ATA-197) and salvage ships USS Safeguard (ARS-25) and USS Current (ARS-22) [1]

Tests

The first shots were performed during test Alpha using 20 short tons (18 t) of HBX explosives detonated 200 feet (61 m) under water. The purpose was to determine the effects of underwater shock on equipment in preparation for the larger surface shots. [9] The crew reported the blast sounding like a large hammer hitting the ship that caused the deck to move out from under their feet and paint to flake off of piping and bulkheads. [10] For the large surface shots, USS Atlanta was the primary close-in target ship, while the others were stationed more distantly so that they could be repaired more readily. For each successive test, the Atlanta would be placed closer to ground zero thus receiving more damage. [1]

Operation Sailor Hat
NameDateTimeLocationTypeYieldShips Present
Alpha12 November 196415:15 PSTOff San Clemente IslandUnderwater20 t USS Atlanta
Alpha14 November 196416:17 PSTOff San Clemente IslandUnderwater20 t USS Atlanta
Bravo6 February 196514:31 HSTSmuggler Cove, KahoʻolaweSurface500 t USS Atlanta, USS Cochrane, HMCS Fraser
Charlie16 April 196515:21 HSTSmuggler Cove, KahoʻolaweSurface500 t USS Atlanta, USS England, USS Benjamin Stoddert, HMCS Fraser
Delta19 June 196511:26 HSTSmuggler Cove, KahoʻolaweSurface500 t USS Atlanta, USS Dale, USS Towers
Detonation for Shot "Bravo", first of a series of three test explosions. USS Atlanta is moored in the left center. Note the shock wave spreading over the water just beyond the ship, and the shock condensation cloud lifting overhead TNT detonation on Kaho'olawe Island during Operation Sailor Hat, shot Bravo, 1965.jpg
Detonation for Shot "Bravo", first of a series of three test explosions. USS Atlanta is moored in the left center. Note the shock wave spreading over the water just beyond the ship, and the shock condensation cloud lifting overhead

A central timing and firing system was on board Atlanta to direct photo planes, smoke rockets and hundreds of recording instruments, the synchronization of which was essential. The test shots resembled a small nuclear explosion, creating a shock wave on the water and an expanding shock condensation cloud. The fireball and mushroom cloud were present but since no nuclear bomb was involved, no radiation or dangerous fallout was produced. The blast created an overpressure of 10 pounds per square inch (69 kPa) on the target, [11] a moving wall of highly compressed air with maximum wind speeds of 294 miles per hour (473 km/h). An overpressure blast of that magnitude is equivalent to a 1 megatonne of TNT (4.2 PJ) burst at roughly 8,000 feet (2,400 m) [12] and is sufficient to be lethal and capable of destroying reinforced concrete buildings. [13] Knowing the yield of the blast, this also implies the Atlanta was placed around 800 feet (240 m) away from ground zero for that particular test. Two blimps were also destroyed high above ground, and a life size mannequin placed on the deck facing the blast was violently thrown over. [14] The first test Bravo also produced a large amount of rock ejecta that caused secondary damage. To solve this problem, the second shot was placed over a five-foot (1.5 m) mound of sand, and the last shot Delta was detonated over the previous crater that was back filled with 39,000 cubic yards (30,000 m3) of sand. [1]

Effects

USS England and USS Atlanta during the second shot Charlie of Operation Sailor Hat Operation Sailor Hat Charlie Shot.jpg
USS England and USS Atlanta during the second shot Charlie of Operation Sailor Hat

On USS Atlanta, over 500 high-speed cameras recorded the effects of the blast. [10] During the tests, the ship was manned by a 169-man navy crew and 60 scientific personnel who remained below deck. In spite of the topside damage, the crew below deck experienced only a shock equivalent to that experienced aboard an Iowa-class battleship firing a nine gun 16-inch salvo. Had there been personnel in the superstructures, they would have been violently thrown about. Topside, the SPS-37 and SPS-10 antennas as well as the URD-4 radio direction finder were torn off by the blast, while other structures were severely deformed. The AN/SPG-51 Tartar guided missile radar was put out of operation for one hour. While the anti-submarine ASROC launcher and Mark 32 torpedo tubes were damaged, the rockets and Mark 44 and Mark 46 torpedoes inside were intact. The Mark 25 torpedo tube was severely damaged, aluminum casting cracked, hold down bolts elongated, the insulating blanket destroyed and the muzzle door sprung, but surprisingly, the tube remained operational. The tripod mast carrying electronics gear was destroyed and fell to the deck. On the blast side, components of the hardened deck house sustained a permanent 2-inch (51 mm) deflection. The entire DLG 16 deck-house between two levels was blown in after welds were ruptured. [11]

USS England was placed farthest from the blast center and thus experienced the least damage, the most serious of which was only a dent where a boulder had hit the ship. The shock wave reportedly caused the ship to move side to side by as much as 4 feet (1.2 m). [10]

On USS Cochrane, power was lost for 5 minutes after the ship was hit by the blast overpressure. She was able to restore power and return to Pearl Harbor Naval Shipyard for a hull and systems inspection and to assess the effects of the blast. The yard was impressed with how well the blast was resisted. After some minor repairs (Both the 3-Dimensional AN/SPS-39 & 2-Dimensional AN/SPS-40 Air Search Radar Antennas had to be replaced) Cochrane was cleared for her first deployment. [15]

Results

The crater created by Operation Sailor Hat Operation Sailor Hat Crater, Kaho'olawe.JPG
The crater created by Operation Sailor Hat

The operation demonstrated that some components were vulnerable to air blast, while others proved quite resilient. However, only low-cost improvements and minor design changes were needed without imposing unacceptable weight and cost factors or compromising operations. For example, although some antennas were incapacitated, antenna designs needed modifying only at the ruggedization level rather than at the concept level. The test data were intended also to be used in better damage-range standoff predictions and to provide design and specification information for better survivability in combat. [11] [1]

In addition to the projects directly associated with the ship evaluation program, various other projects were supported. These dealt with seismic effects, underwater acoustics, radio communications, cratering phenomena, free-field air blast measurements, fireball generation, cloud growth and electromagnetic effects. [11]

The remaining crater left by the blast is called the "Sailor's Hat" crater and holds an anchialine pool containing Halocaridina rubra shrimp, [16] which are salt-tolerant.

See also

Related Research Articles

<span class="mw-page-title-main">Bomb</span> Explosive weapon that uses exothermic reaction

A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechanical stress, the impact and penetration of pressure-driven projectiles, pressure damage, and explosion-generated effects. Bombs have been utilized since the 11th century starting in East Asia.

<span class="mw-page-title-main">Depth charge</span> Anti-submarine weapon

A depth charge is an anti-submarine warfare (ASW) weapon designed to destroy submarines by detonating in the water near the target and subjecting it to a destructive hydraulic shock. Most depth charges use high explosives with a fuze set to detonate the charge, typically at a specific depth from the surface. Depth charges can be dropped by ships, patrol aircraft and helicopters.

Overpressure is the pressure caused by a shock wave over and above normal atmospheric pressure. The shock wave may be caused by sonic boom or by explosion, and the resulting overpressure receives particular attention when measuring the effects of nuclear weapons or thermobaric bombs.

<span class="mw-page-title-main">Operation Crossroads</span> 1946 nuclear weapon tests at Bikini Atoll

Operation Crossroads was a pair of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. They were the first nuclear weapon tests since Trinity on July 16, 1945, and the first detonations of nuclear devices since the atomic bombing of Nagasaki on August 9, 1945. The purpose of the tests was to investigate the effect of nuclear weapons on warships.

<span class="mw-page-title-main">Effects of nuclear explosions</span> Type and severity of damage caused by nuclear weapons

The effects of a nuclear explosion on its immediate vicinity are typically much more destructive and multifaceted than those caused by conventional explosives. In most cases, the energy released from a nuclear weapon detonated within the lower atmosphere can be approximately divided into four basic categories:

<span class="mw-page-title-main">Operation Wigwam</span> 1955 U.S. nuclear test

Operation Wigwam involved a single test of the Mark 90 "Betty" nuclear bomb. It was conducted between Operation Teapot and Project 56 on May 14, 1955, about 500 miles (800 km) southwest of San Diego, California. 6,800 personnel aboard 30 ships were involved in Wigwam. The purpose of Wigwam was to determine the vulnerability of submarines to deeply detonated nuclear weapons, and to evaluate the feasibility of using such weapons in a combat situation. The task force commander, Admiral John Sylvester, was embarked on the task force flagship USS Mount McKinley. Wigwam was the first atomic test in the deep ocean, and it remains the only test that has been conducted in water deeper than 1,000 ft (300 m).

<span class="mw-page-title-main">Operation Blowdown</span> Australian test explosion

Operation Blowdown was an explosives test carried out in the Kutini-Payamu jungle of Australia's Cape York Peninsula in 1963, to simulate the effects of a nuclear weapon on tropical rainforest. It was conducted by the Australian Army, the Department of Supply, and the Defence Standards Laboratory with participation from the United Kingdom, Canada and United States. In addition, blast effects on military material, field fortifications, supply points, and foot and vehicle movement were examined in a rainforest environment.

<span class="mw-page-title-main">Operation Hardtack I</span> Series of 1950s US nuclear tests

Operation Hardtack I was a series of 35 nuclear tests conducted by the United States from April 28 to August 18 in 1958 at the Pacific Proving Grounds. At the time of testing, the Operation Hardtack I test series included more nuclear detonations than the total of prior nuclear explosions in the Pacific Ocean. These tests followed the Project 58/58A series, which occurred from 1957 December 6 to 1958, March 14, and preceded the Operation Argus series, which took place in 1958 from August 27 to September 6.

There have been many extremely large explosions, accidental and intentional, caused by modern high explosives, boiling liquid expanding vapour explosions (BLEVEs), older explosives such as gunpowder, volatile petroleum-based fuels such as gasoline, and other chemical reactions. This list contains the largest known examples, sorted by date. An unambiguous ranking in order of severity is not possible; a 1994 study by historian Jay White of 130 large explosions suggested that they need to be ranked by an overall effect of power, quantity, radius, loss of life and property destruction, but concluded that such rankings are difficult to assess.

<span class="mw-page-title-main">Nuclear weapon yield</span> Energy released in nuclear weapons explosions

The explosive yield of a nuclear weapon is the amount of energy released such as blast, thermal, and nuclear radiation, when that particular nuclear weapon is detonated, usually expressed as a TNT equivalent (the standardized equivalent mass of trinitrotoluene which, if detonated, would produce the same energy discharge), either in kilotonnes (kt—thousands of tonnes of TNT), in megatonnes (Mt—millions of tonnes of TNT), or sometimes in terajoules (TJ). An explosive yield of one terajoule is equal to 0.239 kilotonnes of TNT. Because the accuracy of any measurement of the energy released by TNT has always been problematic, the conventional definition is that one kilotonne of TNT is held simply to be equivalent to 1012 calories.

<span class="mw-page-title-main">Minor Scale</span> Explosives detonation test in 1985

Minor Scale was a test conducted on June 27, 1985, by the United States Defense Nuclear Agency involving the detonation of several thousand tons of conventional explosives to simulate the explosion of a small nuclear bomb. The purpose of the test was to evaluate the effect of nuclear blasts on various pieces of military hardware, particularly new, blast-hardened launchers for the MGM-134 Midgetman ballistic missile.

<span class="mw-page-title-main">Explosives safety</span>

Explosives safety originated as a formal program in the United States in the aftermath of World War I when several ammunition storage areas were destroyed in a series of mishaps. The most serious occurred at Picatinny Arsenal Ammunition Storage Depot, New Jersey, in July, 1926 when an electrical storm led to fires that caused explosions and widespread destruction. The severe property damage and 19 fatalities led Congress to empower a board of Army and Naval officers to investigate the Picatinny Arsenal disaster and determine if similar conditions existed at other ammunition depots. The board reported in its findings that this mishap could recur, prompting Congress to establish a permanent board of colonels to develop explosives safety standards and ensure compliance beginning in 1928. This organization evolved into the Department of Defense Explosives Safety Board (DDESB) and is chartered in Title 10 of the US Code. The DDESB authors Defense Explosives Safety Regulation (DESR) 6055.9 which establishes the explosives safety standards for the Department of Defense. The DDESB also evaluates scientific data which may adjust those standards, reviews and approves all explosives site plans for new construction, and conducts worldwide visits to locations containing US title munitions. The cardinal principle of explosives safety is expose the minimum number of people for the minimum time to the minimum amount of explosives.

USS <i>LSM-60</i> LSM-1-class landing ship medium

USS LSM-60 was a World War II era landing ship, medium (LSM) amphibious assault ship of the United States Navy. It was notable for being used as the float to suspend a fission bomb underwater during the Operation Crossroads BAKER test, becoming the first naval vessel to deploy a nuclear weapon.

1967 USS <i>Forrestal</i> fire Shipboard fire at sea

On 29 July 1967, a fire broke out on board the aircraft carrier USS Forrestal after an electrical anomaly caused a Zuni rocket on an F-4B Phantom to fire, striking an external fuel tank of an A-4 Skyhawk. The flammable jet fuel spilled across the flight deck, ignited, and triggered a chain reaction of explosions that killed 134 sailors and injured 161. At the time, Forrestal was engaged in combat operations in the Gulf of Tonkin, during the Vietnam War. The ship survived, but with damage exceeding US$72 million, not including the damage to aircraft. Future United States Senator John McCain and future four-star admiral and U.S. Pacific Fleet Commander Ronald J. Zlatoper were among the survivors. Another on-board officer, Lieutenant Tom Treanore, later returned to the ship as her commander and retired an admiral.

<span class="mw-page-title-main">Misty Picture</span> United States explosive test

Misty Picture was a test conducted on May 14, 1987 by the United States Defense Nuclear Agency involving the detonation of several thousand tons of conventional explosives to simulate the explosion of a small nuclear bomb.

A sympathetic detonation, also called flash over or secondary/secondaries (explosion), is a detonation, usually unintended, of an explosive charge by a nearby explosion.

<span class="mw-page-title-main">Condensation cloud</span> Product of large explosions in humid air

A transient condensation cloud, also called a Wilson cloud, is observable surrounding large explosions in humid air.

<span class="mw-page-title-main">Nuclear testing at Bikini Atoll</span> US nuclear testing on Bikini Atoll in the Marshall Islands

Nuclear testing at Bikini Atoll consisted of the detonation of 24 nuclear weapons by the United States between 1946 and 1958 on Bikini Atoll in the Marshall Islands. Tests occurred at 7 test sites on the reef itself, on the sea, in the air, and underwater. The test weapons produced a combined yield of about 75 Mt of TNT in explosive power.

<span class="mw-page-title-main">Operation Snowball (test)</span> Canadian conventional explosive test for nuclear weapon detonations

Operation Snowball was a conventional explosive test to obtain information on nuclear weapon detonations run by the Defence Research Board with participation from the United Kingdom and United States. A detonation of 500 short tons (450 t) of TNT was used to study the resulting phenomena. The test was held at the Suffield Experimental Station in Alberta and was the largest ever man-made, non-accidental explosion in Canada. The test was also the first of its kind using a stacked TNT block hemisphere of such magnitude, a method repeated in six subsequent tests such as Operation Sailor Hat and Prairie Flat. The test allowed verifying predicted properties of shock and blast and determining its effect on a variety of military targets at varied distances from ground zero.

<span class="mw-page-title-main">Operation Prairie Flat</span> Conventional explosive test for nuclear weapon detonations

Operation Prairie Flat was a test involving the detonation of a 500-short-ton (450 t) spherical surface charge of TNT to evaluate airblast, ground shock and thermal effects of nuclear weapons.

References

  1. 1 2 3 4 5 6 7 8 9 Reed, Cdr. S. C. (1 January 1966). "Naval Ship Systems Command Technical News". 15 (5–12). Naval Ship Systems Command, Department of the Navy: 54–56. Retrieved 26 April 2017.{{cite journal}}: Cite journal requires |journal= (help)
  2. ↑ "Bureau of Ships journal v.14". Bureau of Ships Journal: 25. January 1965. Retrieved 25 April 2017.
  3. ↑ Defence's Nuclear Agency 1947 – 1997 (PDF). Washington, DC: Defence Threat Reduction Agency. 2002. p. 190. Retrieved 1 May 2017.
  4. ↑ "Naval Historical Center" . Retrieved 17 April 2017.
  5. ↑ Defense Special Weapons Agency, 1947–1997 the first 50 years of national service. DIANE Publishing. 1996. p. 16. ISBN   9781428981508 . Retrieved 27 April 2017.
  6. ↑ "Defence Research and Development Canada | News | DRDC's experimental proving ground supports CAF, allied readiness". www.drdc-rddc.gc.ca. 10 March 2015. Retrieved 27 April 2017.
  7. ↑ "Protect Kaho'olawe 'Ohana" . Retrieved 17 April 2017.
  8. ↑ "Naval History and Heritage Command" . Retrieved 17 April 2017.
  9. ↑ E. L., Harner (March 1977). Guide to High Explosive Field Tests with Military Applications - Yields of 100 Pounds or More. Defence Technical Information Center. pp. 141–144. Retrieved 1 June 2017.
  10. 1 2 3 "USS England official website" . Retrieved 17 April 2017.
  11. 1 2 3 4 "Swordfish Sailor Hat MK57 ASROC ASTOR SUBROC DOE Video #0800046". Youtube. 6 February 2012. Retrieved 25 April 2017.
  12. ↑ Dolan, Philip J.; Glasstone, Samuel (1977). The Effects of Nuclear Weapons. United States Department of Defense. pp. 101, 109. Retrieved 6 May 2017.
  13. ↑ "Overpressure | Effects of Nuclear Weapons | atomicarchive.com". www.atomicarchive.com. Retrieved 24 April 2017.
  14. ↑ Operation Sailorhat 1965 . Retrieved 2014-12-16.
  15. ↑ "USS Cochrane History". USS Cochrane. Retrieved 17 April 2017.
  16. ↑ Brock, R.; J. Bailey-Brock (1997). "An[sic] Unique Anchialine Pool in the Hawaiian Islands". International Review of Hydrobiology. 83 (1): 65–75. doi:10.1002/iroh.19980830107. Archived from the original on 2012-10-20. Retrieved 2010-04-01.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.