Tennessee Class Cruiser - Modernization Plans

Modernization Plans

After the Washington Naval Conference of 1922, the question of modernization was looked into since, by law, the three Tennessees still in service would be more powerful theoretically than any new cruisers. In May 1922, C&R studied conversion of the power plants to give them a speed of 25 or 27 knots "without excessive expenditures of power or without taking a prohibitive amount of water onboard due to freeboard." A study of weight distribution showed enough similarity between these ships and the Omaha-class scouts to promise they would behave no worse than the scouts on the open seas. Discussions, which continued into 1923, included flaring the bows in keeping with the design for the now-defunct Lexington class battlecruisers, conversion to oil burning, added torpedo protection and an armament upgrade to 8-inch (200 mm) 55 caliber guns in triple turrets. Eventually, nothing was done.

Modernization was considered again in 1928. This would include the installation of 8-inch/55 guns, an anti-aircraft battery, fire controls, oil-fired boilers and torpedo bulkheads. The estimated cost of $6 million did not include new engines. It was argued that, despite the 1922 study, a significant increase in speed would be prohibitive in cost as "the underwater lines of these ships do not lend themselves to these increases." It was conceded that without an increase in speed, the ships had little tactical value and the war plans division of Opnav argued from the opening discussions that modernizing them would be pointless. They could still prove useful, others argued, as support for the battle fleet, where their speed would match that of current battleships. In this role, they could screen and support destroyers against enemy cruisers.

The main issue turned out to be political, with War Plans concerned that reconstruction of the Tennessees might disrupt the building of new cruisers and with doubts about whether they would compare to more modern ships, even with their superior tonnage. Costs had escalated to $17 million and it did not seem profitable to modernize ships that would be between 25 and 28 years old once modernization was complete. Also, the Bureau of Ordnance did not consider replacing their guns practical. This meant that, if these ships were kept in service 15 years after modernization, they might eventually face weapons over 40 years more advanced than their own. Despite these developments, detailed studies continued.

C&R found it could install a 58,000–shaft horsepower power plant similar to one planned for the new aircraft carrier USS Ranger without disturbing the existing shaft lines of the cruisers; this would give them a speed of 26 knots. The Bureau of Ordnance could increase elevation of the 10-inch guns to 40 degrees, which would increase their range to 31,000 yards (28,000 m). However, in a comparison with the Pensacola-class ships then being built, the newer ships showed themselves at an advantage in gunnery range and equal in protection. Modernization plans were thereby abandoned.