HistoryData
Historical ConflictKahoolawe

Operation Sailor Hat

Operation Sailor Hat provided the U.S. Navy with critical data on nuclear blast effects on ships using conventional explosives, the first such major test since 1946.

Duration & Scope

1964 1965

1 year

Key Facts

Explosive charge per test
500 short tons (454 t) of TNT/HBX
Equivalent nuclear yield simulated
1 kiloton at greater distance
Kahoʻolawe surface tests
3
San Clemente underwater tests
2
Prior comparable test
Operation Crossroads, July 1946
Primary test vessel
USS Atlanta (Cleveland-class light cruiser)

Strategic Narrative Overview

The operation unfolded in two phases: two underwater explosions at San Clemente Island, California in 1964, followed by three surface detonations at Kahoʻolawe, Hawaii in 1965. Each Hawaiian test used a dome-stacked 500-short-ton TNT charge detonated near participating vessels, including USS Atlanta, USS England, USS Dale, USS Cochrane, USS Benjamin Stoddert, USS Towers, and the Royal Canadian Navy's HMCS Fraser, representing a mix of older and newly constructed warships.

01 / The Origins

Following Operation Crossroads in 1946, the U.S. Navy lacked recent empirical data on how nuclear weapon blasts affected surface warships. By the early 1960s, with nuclear warfare remaining a credible threat, the Bureau of Ships and the Defense Atomic Support Agency sought to assess and improve the blast resistance of modern naval vessels. Large conventional explosive charges were chosen to simulate nuclear effects without conducting an actual nuclear detonation.

03 / The Outcome

The tests concluded successfully, generating extensive data on shock and blast effects experienced by naval ships. The findings informed improvements to blast resistance standards and damage control procedures across the U.S. Navy fleet. No nuclear materials were used, and the operation demonstrated that large-scale conventional explosive testing could serve as a viable proxy for evaluating nuclear weapon effects on modern warships.

Belligerents & Mobilization Analysis

Side A

1 belligerent

United States Navy / Defense Atomic Support Agency

Side B

1 belligerent

Royal Canadian Navy (observer/participant)
Outcome
Tests completed successfully; data collected on nuclear blast effects on naval vessels, informing improvements to ship blast resistance.

Location

Map of Kahoʻolawe, United StatesMap of Kahoʻolawe, United StatesKahoʻolawe, United States