Iowa class

2023-02-01 -

USS IOWA

Arguably, the Iowa class was the largest, most modern, well-armed, and functionally sound battleships ever conceived and were the last of their kind constructed by the

US. The USS Iowa, commissioned on 22 February 1943, was the lead of four Iowaclass battleships constructed. Progressing onward from the design and performance improvements derived from the previous classes of battleships (North Carolina and South Dakota) the Iowa class would be further improved by enlarging the size of the ships, fitting them with additional and improved armament, greater armour protection, a higher top speed, and advanced radar systems. This class of ship would have the capability of keeping up with modern aircraft carriers thus enabling them to provide greater protection.

The Iowa-class battleships were incredibly long at 860ft resulting from a lengthened forecastle and amidship (which increased their speed), had a beam of

108ft 2in, and a full load displacement of 57,540 tonnes. The ships also had a bulbous bow in lieu of the sharper taper of previous battleships which caused very powerful ocean spray and could obstruct the view from the bridge during refuelling operations for their destroyer escorts. A similar nuisance was created from the hull design where it abruptly widened, but other than the decks being wet, the ships were incredibly stable at sea which improved the accuracy of their armament.

The primary guns used on these battleships were upgraded from 45 to 50cal, meaning the guns were 66ft long which is 50 times (or calibres) their 16in bore. As with the two previous classes of battleships, there were nine guns housed in three gun turrets, two forward of the battleship’s superstructure and one aft each weighing 267,900lb. They could fire a 2,700lb armour piercing shell 24 miles (about one mile further than a 45cal gun) and it required between 85 and 110 men to operate each turret. In as much as each gun barrel could be elevated and operated independently, the ship could fire any combination or a broadside of all nine guns. The Iowa class was outfitted with 20 highly reliable and accurate 5in/38cal

Mark 12 guns in 10 ring mounts operating as a dual purpose gun in that it could successfully fire at both surface and air targets with a reasonable degree of success. All the Iowa class ships were equipped with 20 quad 1.6in and 49 single mounted guns and to improve accuracy, were fitted with Mk 14 range sight and Mk 51 fire control system. They were later replaced with the heavier Bofors 1.6in AA gun. The ships were also built with .50cal machine guns, but those were phased out in favour of the Oerlikon 0.8in gun. Additional guns were added as the war progressed.

Power was supplied by eight 600psi Babcock & Wilcox boilers and four sets of double reduction cross-compound geared turbines, with each turbine set driving a single shaft. The ship’s propellers were

17ft in diameter and there were a set of four-blade and pair of five-blade models. Two rudders gave the ships a tight tactical turning diameter of 814yd.

The installed electronic countermeasures consisted of SPT-1 and SPT-4 equipment. Passive electronic support measures were a pair of DBM radar direction finders and three intercept receiving antennas, while the active components were the TDY-1

USS Iowa

Class: Iowa

Displacement: 58,400 tonnes

Length: 887ft 3in

Beam: 108ft 2in

Draft: 37ft 2in

Speed: 33 knots

Range: 17,261 miles

Crew: 2,788 men

Armament: 9 × 16in • 20 × 5in guns • 76 × 1.6in AA guns • 52 × .80in AA guns

Armour: Decks - main 1.5in, second 6in; Waterline belt - 12.1in

USS NEW JERSEY

On 16 September 1940, the second Iowaclass battleship USS New Jersey was laid down at the Philadelphia Naval Shipyard and after the attack on Pearl Harbor, construction rapidly progressed until her commissioning on 23 May 1943.

It took the remainder of that year to complete her shakedown and crew training but, in January 1944, she reported for combat support operations in the Marshall Islands including the invasion of Kwajalein. During 17-18 February, New Jersey screened carriers as they conducted raids on the Japanese base at Truk and from there, continued escort activities and shelled enemy positions on Mili Atoll in March.

During the period of 3 April-4 May the ship provided air support for the invasion of Aitape and Tanahmerah Bay, then moved to Humboldt Bay for more action before shelling shipping and shore installations on Truk 29-30 April. She attacked Ponape two days later.

On 13-14 June, New Jersey bombed targets on Saipan and Tinian in preparation for the Allied landings and a few days later, provided anti-aircraft defence during the Battle of the Philippine Sea. She next supported attacks in the Palau’s before steaming for Pearl Harbor to become the flagship of Admiral Halsey.

Sailing for Ulithi, New Jersey had a busy September screening carriers and bombing targets in the Visayas, the southern Philippines, then Manila and Cavite, Panay, Negros and Cebuacross. In October, she provided cover for the landings on Leyte and participated in the Battle of Leyte Gulf. For the following two months, New Jersey and the carrier task force renewed their attacks around the Philippines constantly battling unrelenting enemy air and kamikaze attacks.

While steaming in the Philippine Sea, on 18 December thew task force fleet was suddenly struck by the tremendous force of Typhoon Cobra. Many American ships were damaged including the USS Iowa and three destroyers were sunk, however, the New Jersey was virtually unaffected.

In January, New Jersey screened carriers and shelled targets as the force launched attacks against Formosa, Luzon, French Indochina, Hong Kong, Hainan and Okinawa. In February, she protected the carriers supporting the invasion of Iwo Jima before sailing north to join in the attack on Tokyo.

On 14 March 1945, New Jersey commenced operations supporting the invasion of Okinawa where she fought off air raids, used her seaplanes to rescue downed pilots, and defended carriers from kamikaze planes shooting down at least three and assisting in the annihilation of many others. For the next month, she protected the carriers from persistent Japanese air attacks with her superior firepower and supported the invading Allied forces with her big guns.

Ordered to Puget Sound Navy Yard for a refit, once completed New Jersey sailed on 4 July to partake in the invasion of Guam and the Palaus. Following the end of hostilities, she arrived in Tokyo Bay on 17 September, two weeks after the surrender of Japan. For her contribution in the war, New Jersey received 19 battle stars, a phenomenal number for a relatively short time in service.

USS WISCONSIN

The USS Wisconsin was constructed at the Philadelphia Navy Yard and commissioned on 16 April 1944.

After her trials and initial training, the

USS New Jersey / USS Wisconsin

Class: Iowa

Displacement: 58,400 tonnes

Length: 887ft 3in

Beam: 108ft 2in

Draft: 37ft 2in

Speed: 33 knots

Range: 17,261 miles

Crew: 2,788 men

Armament: 9 × 16in guns • 20 × 5in guns • 76 × 1.6in AA guns • 52 × .80in AA guns

Armour: Decks - main 1.5in, second 6in; Waterline belt - 12.1in

USS MISSOURI

The USS Missouri (Mighty Mo) was the last Iowa-class battleship commissioned and has the distinction of being the final battleship constructed by the United States. Although she participated in several WWII battles, she is best known as the location of the Japanese surrender on 2 September 1945, denoting the end of WWII.

In reaction to America’s anticipations for an imminent war with the Empire of Japan, the US Navy designed the Iowa class of fast battleships, in the late 1930s, to be the largest and fastest vessels of their type. Design studies prepared during the development of the earlier North Carolina and South Dakota classes confirmed the struggle to construct a fast, heavily gunned and well armoured battleship within the confined weight and gun limitations of the Washington Naval Treaty that controlled capital ship construction.

However, the clause contained within the proposed 1936 Second London

Naval Treaty permitted a ship to weigh an additional 10,000 tonnes if every member nation did not sign the document. The refusal of the Japanese to ratify the agreement opened the door for American marine architects to increase the weight of the Iowa class to 45,000 tonnes.

At a length of 887ft 3in, Missouri had plenty of space to house the arsenal of weaponry she carried which consisted of a main battery of nine 16in/50cal

Mark 7 guns, a secondary battery of

20 x 5in/38cal dual purpose guns, 20 quadruple mounts for 1.6in Bofors AA guns, and 49 x 0.8in Oerlikon light AA autocannon in single mounts distributed throughout the length of the ship.

The sophisticated weapon systems aboard Missouri left nothing to chance as they were operated by sailors utilising modern electronic systems. The 16in guns, better known as the main armament, were equipped with a primary sensor known as the Mark 8 fire-control radar mounted on their turret roofs. The guns were also controlled by two Mark 38 directors that were components of the Mark 38 fire-control system. To get the longest distance benefit from the directors, they were installed on the superstructure in the forward and after fire-control towers. The directors for the rangefinders were quite long and measured 25ft 6in.

In case of damage from enemy fire or a component failure, a back-up Mark 40 fire-control director was positioned inside the forward area of the conning tower on the superstructure that mated with the Mark 27 fire-control radar system located positioned on the top of the conning tower. The final electronic system associated with the main guns was a 46ft rangefinder installed on each turret that, in case of damage, was co-mingled with the other guns to direct their fire.

Controlling the 5in guns were four Mark 37 gunnery directors, two of which were installed on centreline at opposing ends of superstructure and one on each side of the ship. All the directors were outfitted with rangefinder 15ft in length and a pair of Mark 12 fire-control system and a Mark 22 height-finder radars. A Mark 51 director combined with a Mark 14 lead-computing gyro gunsight remotely controlled the 1.6 AA mounts and the targets of the 0.8 guns were sighted by using a Mark 14 system for controlled tracking.

Fitted on the ship’s foremast was an