Were The Iowa Class Battleships Flawed?

Were The Iowa Class Battleships Flawed?


Let’s look at the armor and protection problems of the Iowa class battleships.

The Iowa class battleships were a group of four fast battleships built by the United States Navy in the 1940s. The ships of the class were USS Iowa (BB-61), USS New Jersey (BB-62), USS Missouri (BB-63), and USS Wisconsin (BB-64). They were the last battleships built by the US Navy, and were among the largest and most heavily armed ships of their time. The Iowa class battleships were commissioned during World War II, and saw action in the Pacific theater.

They were also used during the Korean War and in the Persian Gulf War. After being decommissioned, the Iowa and Missouri were later reactivated and modernized for use in the 1980s and 1990s. The USS Missouri is notable as the site of the official Japanese Surrender in World War II.

One historian Dr George H Elder points to problems with their torpedo protection which didn’t receive proper testing.

Moreover, propellant containment is not the only weak point Dr. Elder’s assessment of the Iowa Class battleship’s design.
Missouri fires 16 in guns at Chong Jin, Korea, 21 October 1950

Dr. Elder points to a few issues, from radar protection, to torpedo protection, but really hits on general armor protection.

In the Iowa and South Dakota designs both weight and the advent of Japanese shells with underwater trajectories had to be considered. The designers felt they did not have sufficient weight margins available to employ a heavy multi-layered system against underwater attacks and thick side armor as well. In lieu of making the design changes necessary to employ separate underwater and shell protection system, American naval designers opted to use a common system for both purposes. As Oliver North would say, “It was a neat idea.”

The side armor of the Iowa class was set several feet inboard, and inclined internally at 19 degrees to the vertical until it reached the top of the ships’ triple bottoms. It was reasoned the side armor would thus form a formidable torpedo protection bulkhead (6.4″ to 1.62″) as well as keep shells with underwater trajectories out. Despite the lack of full scale tests, the system was immediately incorporated in both the South Dakota and Iowa Class. That’s good old Navy foresight for you, although in all fairness to the designers they were pressed for time due to the looming war.

In 1939 the Iowa’s under-water protection scheme was finally tested on full scale models in the Philadelphia Navy Yard.

The results of the trials were very disappoint­ing. It was discovered that the heavy Class B armor used in the torpedo bulkhead could not bend enough to accept the gas pressures generated by large underwater contact explosions. The system failed due to armor plate cracks and structural failures where the bulkheads joined into the ship’s triple bottom. These defects allowed flooding to take place behind the main torpedo bulkhead, and the system had to modified.

The modified torpedo protection system was tested in 1943 at the Philadelphia Naval Yard. The results were less than satisfactory and again showed structural defects, but these faults were deemed acceptable. Corrective plans were finally drawn up, but they were too late for the Iowa and her three sisters. Had the Illinois and Kentucky (Iowa Class near sisters) been completed, they would have incorporated the improved torpedo protection scheme. However, their construction was halted and both ships were ultimately scraped.

Some Navy officials were displeased with the Iowa Class’s underwater protection scheme very early on. In 1944 P. W. Snyder, a Commander in the Bureau of Ships, filed a scathing report on the battleships’ design. He felt the Iowa Class needed six feet more beam and better sub-division to have adequate torpedo protection. But Snyder’s recommendations were rejected by his superiors. It was felt a wider hull would make the ships slightly slower and unable to go through the Panama Canal. Improving the ship’s internal sub-division was too expensive and time-consuming to even consider. So in the end nothing was done.

Richard Debobes, a staffer for the Senate Armed Services Committee, was unaware of the 1939 and 1943 trials on the Iowa Class’s torpedo protection system.

“I can’t comment,” he said. “You must understand that there is an investigation of the turret explosion. These other concerns you have brought up have not even been discussed.” It would appear that the Committee’s staffers are so intent on studying one tree that they are failing to take into account how the forest is faring.

But Debobes is not alone in his unfamiliarity with the trials on the Iowa Class’s torpedo defense system. No staffer from either the House or Senate Armed Services Committee was aware of these tests. Considering the greatly improved performance of the latest torpedoes, one would hope someone notices there’s a problem here. The underwater pressure forces created by modern torpedos and mines are far greater than those that were used in the Philadelphia tests. Two or three hits by modern underwater explosive devices might be more than sufficient to disable or capsize one of these glass-skirted leviathans.

What is of more concern is the possible use of underwater weapons with large shaped-charge warheads. If one of these was to hit an Iowa Class battleship there is the distinct possibility hot gases and debris could penetrate one of their magazines–especially the magazine that supplies Turret I (the turret closest to the ship’s bow). The magazine of Turret I is closer to the sides of the ship than the magazines used to supply turrets II and III. The vulnerability of Turret I’s magazine has been a source of concern since these battleships were designed but the Navy accepted the risk given the fine forward hull form needed to achieve the Iowa Class’ high speed.

Admiral Kinnear admitted that the Iowa Class’s underwater protection was suspect before the ships became reactivated.
Official portrait of Adm. George E.R. Kinnear II

He said, “We knew that the ships’ underwater protection was a potential weak point, but I don’t recall being briefed on the tests that took place in Philadelphia.” Kinnear went on to say that survivability and armor distribution talks took place in Navy Secretary Lehman’s office, but the precise details of these talks can’t be released for security reasons.

Navy spokesperson Walker didn’t know about the Philadelphia tests on the Iowa Class’s underwater protection scheme. “I’m not aware of those tests,” he said. “Nothing is in the works to improve the ships’ underwater protection that I’m aware of. I don’t think it’s an area of concern.” After being told about the Philadelphia test results Walker continued to insist the reactivated battleships “can take more torpedo hits than most ships” in the modern Navy. Walker’s view certainly doesn’t say much for the underwater protection of our modern warships.

Ship Record’s John Reilly also didn’t recall any details about the Philadelphia tests, but said rectifying any shortcomings in the Iowa Class would be difficult.
The hull of Kentucky is floated out of drydock to allow it to be used for repairs to Wisconsin

“You’re talking about a total underwater rebuild, and it’s not necessarily worth it,” he said. “The ships are protected by escorts that will keep submarines away.” Reilly explained the Iowa Class has a number of redundant systems that should limit damage from torpedoes. However, he refused to speculate on the effect a shaped-charge torpedo warhead would have on an Iowa Class’s magazines.

But there are other areas of concern regarding the reactivated battleships besides their dubious underwater protection scheme. Navy spokesperson Walker said the Iowa Class has the thickest armor of any warship afloat. But enormous areas of these battleships are completely unarmored. Of course, these unarmored areas just happen to be where many Navy crewmen serve during battle-stations–another “neat idea.”

The Iowa Class was designed at a time when the US navy embraced the “all-or-nothing” scheme of armor protection.

Heavy armor was restricted to the vital parts of the Iowa Class, and made thick enough to prevent large caliber shells from penetrating it. All other parts of the ships were left unarmored in any meaningful way. The extent of unarmored area was increased in the Iowa Class’s case because their main armor is internal. In short, an armored raft was placed inboard of a relatively unarmored hull and upper deck.

The entire waterline of the Iowa Class is protected by a mere 1.5″ thick armor plates. The ship’s heavy 12.1″ thick main armored belts are set several feet inside the hull. The deck armor of the Iowa Class is also internal. The main deck is only 1.5″ thick, while two decks down the main armored deck is 6.0″ thick.

Most decks above the armored deck are very lightly protected in the Iowa Class, as are the bridge, fire control directors, superstructures, and external communication devices. The secondary turrets that house the Iowa Class’s 5″ guns only have a maximum of 2.5″ of armor plate. In fact, vast areas above the weather deck have no armor at all. The only structures above the weather deck that are heavily protected are the gun turrets, barbettes, and conning tower. All crew members serving outside these areas are vulnerable to even light shell and missile hits.


However, radar systems don’t work all too well when encased in steel!
USS Wisconsin (BB-64) WisKy A History of the Iowa Class Last American Battleship with Keith J. Nitka
So the main criticism on the Iowa’s rests on their ‘immunity zone’!

What is an ‘immunity zone’?

A battleship immunity zone refers to an area or region where a battleship is immune or protected from attack or interference. This could refer to a physical location, such as a designated safe harbor or port, or a legal or political designation, such as a treaty or agreement between nations that prohibits the targeting of battleships in a certain area. The concept of a battleship immunity zone is not a commonly used term in military or naval contexts.

Written by bsbr

Were The Iowa Class Battleships Flawed?