Lexington Class Aircraft Carrier - Development

Development

The Lexington-class were originally designed as battlecruisers, with heavy guns, high speed, and moderate armor protection. The Navy laid down six ships of the class from 1916 to 1919. When the battlecruisers were cancelled under the Washington Naval Treaty of 1922, two of the unfinished ships were designated for completion as carriers. Lexington and Saratoga were selected since they were the most advanced of the six ships in construction. Conversion became a series of compromises and mixed blessings which would not have arisen had they been "specifically designed carriers" from the outset. On the plus side, the ships would have better anti-torpedo protection, larger magazines for aircraft bombs and, with the after elevator 28 feet (8.5 m) higher than otherwise, more room for aircraft landings. On the minus side, a converted battlecruiser would be .5 knots (0.93 km/h) slower than a specifically designed carrier, have 16 percent less hanger space, less emergency fuel and, with "narrower lines" aft, not as wide a runway for which to aim. Costs were similar. A brand-new aircraft carrier was estimated at $27.1 million. Conversion of a Lexington class was $22.4 million, not counting the $6.7 million already sunk into them. Added together, the figure rose to $28.1 million.

The bottom line, with the signing of the treaty, was that any capital ships under construction by the five signatories (the United States, Great Britain, France, Italy and Japan) had to be canceled and scrapped. For battlecruisers, this encompassed the United States' Lexington class, Japan's Amagi class, and Great Britain's G3 battlecruisers. For the U.S. Navy, the choice seemed clear. If it scrapped all six Lexingtons in accordance with the treaty, it would throw away $13.4 million that could otherwise go toward aircraft carriers. The Navy opted for the latter course.

The next challenge the Navy's Bureau of Construction and Repair faced was the tonnage cap set by the treaty. Carriers were to be no more than 27,000 tons. An exception, spearheaded by Assistant Secretary of the Navy Theodore Roosevelt Jr. and added to the treaty, allowed capital ships under conversion to go up to 33,000 tons, an increase of 6000 tons. This would almost not be enough for a conversion without removing half the power plant, something the Navy General Board did not consider an option. Creative interpreting of a clause in the treaty allowed a potential way out of this situation. The clause (Chapter II, Part III, Section I, (d)) read:

No retained capital ships or aircraft carriers shall be reconstructed except for the purpose of providing means of defense against air and submarine attack, and subject to the following rules: The Contracting Powers may, for that purpose, equip existing tonnage with bulge or blister or anti-air attack deck protection, providing the increase of displacement thus effected does not exceed 3,000 tons (3,048 metric tons) displacement for each ship. No alterations in side armor, in calibre, number or general type of mounting of main armament shall be permitted except:

(1) in the case of France and Italy, which countries within the limits allowed for bulge may increase their armor protection and the calibre of the guns now carried on their existing capital ships so as not to exceed 16 inches (406 millimeters) and

(2) the British Empire shall be permitted to complete, in the case of the Renown, the alterations to armor that have already been commenced but temporarily suspended.

Without this clause, conversion might not have been feasible. Estimates made in 1928 estimates for the two ships put Lexington at an actual tonnage of 35,689 tons and Saratoga at 35,544. On official lists, the number given was 33,000 tons, with the footnote, " does not include weight allowance under Ch. 11, pt. 3, Sec. 1, art. (d) of Washington Treaty for providing means against air and submarine attack". This tonnage number was the one these ships carried for their entire careers.