Summary and Key Points: The USS Wasp (CV-7) was a U.S. Navy aircraft carrier designed under the constraints of the Washington Naval Treaty, which limited its size and capabilities.
-Commissioned in 1940, Wasp was smaller and more lightly armored than other carriers, making it vulnerable in combat.
-Despite its design compromises, Wasp contributed to World War II efforts until it was sunk by Japanese torpedoes in 1942.
-The ship's inadequate firefighting capabilities, exacerbated by battle damage, led to uncontrollable fires that ultimately caused its loss. Wasp’s fate highlights the challenges of treaty-limited warship design.
The U.S. Navy rose to prominence during World War II from just one of many major naval powers to the undisputed greatest in just four short years.
This was in large part due to the expansion and effective use of its aircraft carrier fleet. Although most American flattops that fought in the war were highly successful designs one, USS Wasp, was fatally compromised by the need to conform to international treaty obligations. The result was a carrier that was quickly sunk early on in the war, making only a modest contribution to the overall effort.
One of the most ambitious conventional arms control treaties ever signed was the Washington Naval Treaty. The multinational treaty was negotiated between 1921 and 1922 and resulted in limits in the size of individual warships and the overall tonnage of the navies of the United Kingdom, United States, Italy, and France.
The Washington Naval Treaty had two major provisions: the limitation of fleets and individual warships by tonnage. The treaty limited the size of battleships and battlecruisers built by participants to 35,000 tons or less. The treaty also limited participating countries to a ratio of 5:5:3:1.75:1.75 for the UK, the United States, Japan, Italy, and France. In other words, for every 5 tons of warship the treaty authorized the U.S. to build, Italy could build 1.75 tons. The United States was restricted to 525,000 tons for the overall size of its fleet (the equivalent of five of today’s Nimitz-class supercarriers) and 135,000 tons of aircraft carriers--of which individual carriers could weigh no more than 27,000 tons.
Throughout the 1920s the United States had three aircraft carriers: USS Lexington, USS Saratoga, and USS Langley, the first purpose-built U.S. Navy carrier and technically as an experimental ship not part of the treaty. The Navy’s had allocated all but 14,700 tons of its carrier treaty allowance and decided to build a small carrier, USS Wasp, with the remaining tonnage. The particular compromises allowed by the Navy to keep it within its weight obligation ultimately doomed the ship during its trial by fire in 1942.
USS Wasp (CV-7) was authorized by Congress in March 1934, at the height of the Great Depression, laid down in April 1936, launched in April 1939, and commissioned in April 1940. The Navy tried to fit as many features from the larger Yorktown-class carriers into Wasp, but the latter was a full 5,000 tons smaller than the former, and adding all of them was physically impossible. The smaller carrier was relatively modest by the standards of fleet carriers. CV-7 was 688 feet long at the waterline with an overall length--including flight deck--of 720 feet. She had an overall beam of 109 feet, weighed 14,700 tons empty and 19,000 tons fully loaded.
The demands of the treaty instilled a number of weaknesses in Wasp. Armor was extremely light for a peacetime aircraft carrier, with machinery, magazines, aviation fuel, and rudder control all covered by a maximum of 4 inches of armor. Vital spaces in the island only had only .75 inches of armor, and the conning tower had just 1.5 inches of armor. Other issues included a Wasp had a unique round bottom, a hull strengthened only to the hangar deck, and the ship was the “last combatant ship to have a transversely framed hull”. As a result, Wasp was uniquely susceptible to damage and the ship’s best bet to avoid sinking in combat was to outmaneuver the enemy.
Another major problem with Wasp went undiagnosed until the fatal attack that sunk her in 1942. Although the Navy had judged her as having excellent firefight capabilities, these came up short during an actual attack. The ship was ultimately done in by out of control fires that the crew was unable to control. A wartime report prepared by the Navy blamed Wasp’s poor firefighting efforts on a combination of poor water pressure, damage to existing fire fighting facilities, other fire fighting facilities that came up short, and the existing gasoline stowage system, which was active, that fed the fires.
On September 15th, 1942 USS Wasp was struck by three torpedoes from the Imperial Japanese Navy submarine I-19. Wasp at first though survivable and was even able to remain under her own power, but gasoline fires swept through the ship and made her recovery impossible. After five hours the order was given to abandon ship, and Wasp was scuttled by three torpedoes fired by the destroyer USS Lansdowne. Of the ship’s 2,247 crew, 193 were killed and 366 wounded.
Wasp was not a terrible aircraft carrier, but she had enough shortcomings to succumb to battle damage in September 1942. Although she had light armor, the Navy concluded that she could have survived the three torpedoes that struck her were it not for the fires that followed.
The carrier’s firefighting capabilities were in large part hobbled by battle damage from the torpedo attacks, so it could well be argued that a better-protected ship would have had a better organized and effective damage control effort. While not all of the ship’s shortcomings contributed to the sinking, a better ship not constrained by the demands of a treaty might well have shrugged off the torpedoes and kept fighting.
Kyle Mizokami is a writer based in San Francisco who has appeared in The Diplomat, Foreign Policy, War is Boring and The Daily Beast. In 2009 he cofounded the defense and security blog Japan Security Watch.
