USS Kentucky

USS Kentucky (BB-66) was a unique experimental American battleship based on the Iowa-class. The USS Kentucky tested several improvements planned for subsequent battleships based on war experience and advancements. The USS Kentucky was the first fully welded battleship, as well as the first US battleship to be armed with 18in guns. She also served as a testbed for 5in/54 guns, as well as 3in/70 AA Guns.

## Background:

USS Kentucky was ordered as the sixth member of the Iowa-class. Laid down in early 1942, work on her was paused in early 1943.  With USS Montana ordered in early 1943, and subsequent plans for the Michigan-class made the Kentucky obsolete on the slip. While talks of canceling her were floated, it was decided for her and her sister ship Illinois were to be converted. Her sister USS Illinois was converted into a carrier, however, Kentucky was too far along in construction to be converted into a CV.

The USN decided that Kentucky would be completed as a testbed for newly developed armament planned for potential next-generation Battleships, as well as integrate changes that would reflect changes made elsewhere in the fleet. The biggest change would be to her armament. By 1942, intelligence indicated that the Yamato-class previously suspected 16.1 in guns were actually 18.1in guns. This was coupled with news that the new under-construction Japanese Aki-class and German Tegetthoff-class would both use 20.1in Guns. In the wake of this, the USN was left scrambling for a gun capable of countering these new threats. The Montana-class and Michigan-class would serve as a stop-gap, but the US needed an 18in armed battleship to serve as proper counters.

The first iteration of the 18in gun, the Mark 1, was ultimately rejected in favor of the Mark 7 16in guns used on the Iowas, which had a similar performance to the 18in gun. However, work continued and lessons learned from the development of the Mark 7 Superheavy shell spurred the development of an improved 18in gun called the Mark 2. This new gun had improved ballistic characteristics, believed to be on par with the Japanese 20.1in gun.

By 1943, wartime experience had led to changes in USN Shipbuilding philosophy. This change resulted in revised condensed superstructures with better secondary placement. These changes were seen on the new Fargo-class and Oregon City-Cruiser.

## Design:

With an incomplete hull of the USN’s newest and most prized warships, work on USS Kentucky was to resume with new improvements made to her based on war experience and without the limitations of the 45000tonne limit of the Washington Naval Treaty. The USS Kentucky project was personally overseen by Admiral Ernest King and Admiral Chester Nimitz with changes made to her based on their specification. These changes largely concerned her armament and superstructure design.

The preceding Iowa-class battleships were constructed using a combination of riveting and welding. However, the USS Kentucky, along with USS Illinois, was to be the first battleships to be fully assembled by welding. This change alone saved over 4500 tonnes of weight. Further weight was removed by the removal of the 17.3in thick armored conning tower, and replaced with a conning tower with only 5in of armor. The additional ballast freed up by these changes allowed the USN to further upgrade USS Kentucky’s bulkheads to 17.5in. This change also allowed her to carry several thousand more tonnes of fuel over the Iowa-class, increasing her range dramatically.

The USS Kentucky was the first US Battleship completed armed with 18in/50 Mark 2 guns mounted in twin turrets. While based on the earlier Mark 1, these new guns were vastly improved using lessons learned from the development of the super heavy shell for the 16in guns.

In addition to this, her superstructure was completely reworked at the behest of Admiral Ernst King and Admiral Nimitz. This new superstructure would reflect improvements also made to the Fargo-class and Oregon City-class cruisers. The new superstructure truncated the twin funnels into a single funnel while moving the bridge aft. The 17.3in armored conning tower was removed and replaced with 5in special treated steel. This extra space allowed for the addition of 2 extra secondary mounts fore and aft of the C and B turrets respectively. While 10 gun mounts were still installed, this arrangement allowed for an additional secondary turret to be brought to bear on either broadside over her fellow Iowas. Additionally, the broadside secondary battery gun mounts were dropped a deck over her sisters, to Main deck and 01 level respectively. These new gun mounts would be armed with the new improved 5in/54 Gun mounts- the same gun mounts to be used on the Montana-class.

Her entire AA Armament was completely overhauled as well. The USS Kentucky was the first battleship armed with the new twin 3in/70 AA gun mounts in place of the traditional quad 40mm Bofors. Her 20mm armament was also completely redone, with a new experimental Quad-20mm gun mount system called the “Elco Thunderbolt” being installed in place of whole 20mm batteries.

Finally, her torpedo protection bulkheads were slightly revised. The previously angled knuckles were made perpendicular. This new system increased the effectiveness of the Torpedo system by 20%.

## Service History:

Commissioned into active service in 1946, the USS Kentucky was deployed to the South Pacific Fleet as a counter to the Japanese Super Battleships.