November 11, 2020

The Alaska Class Part 2

As the naval treaties lapsed in the late 30s, a new type of ship became possible, something more powerful than the treaty cruisers but smaller than a full-size battleship. Several nations looked into building this kind of ship, but only the US actually built them, in the form of the Alaska class large cruisers. The process of actually reaching a consensus in favor of the ships was tortuous, and things got even worse when it was time to actually design them.


Alaska on her shakedown cruise

The first batch of design studies were an interesting hybrid of cruiser and battleship practice. Unlike contemporary cruisers, they were given a proper TDS, although one designed against a 500 lb charge instead of the 700 lbs of the Iowas. The inner edge of the immune zone was set at a much shorter range than was common for battleships, as a ship operating independently might well have short-range encounters that a battleship's screen would intercept. Three of the four were to be protected against the extremely powerful 12" gun, which in turn pushed up size and led designers to use more elements of battleship practice. This formed a vicious cycle, and the largest design from the initial phase, armed with 12 12" guns, had a standard displacement of 38,700 tons, larger than the North Carolina and South Dakota classes. Another, with 9 guns and a bigger immune zone, actually had a thicker belt than the Iowas. All of these designs were rightly seen as too big, with two Iowas costing as much as three of the smallest design armored against the 12" gun.


The design for the "convertible cruiser"

The designers were sent back to the drawing boards to try again, including a rather odd request to study a ship that could be armed with either 12 8" or 6 12" guns interchangeably. Three of the four barbettes were designed to take either a triple 8" or a twin 12", while the fourth would be left empty if the 12" gun was selected. The motivations behind this plan are not entirely clear, but it seems that the General Board was worried about foreign cruiser-killers making an unexpected appearance. They could either switch the ships over quite late in design, or replace the guns after they entered service, giving a quick response if they found foreign ships outmatching their 8" cruisers. In any event, this plan was discarded, and after much wrangling between those in favor of a slightly bigger 8" cruiser and the faction who wanted a balanced 12" ship, a compromise design was settled on. The side protection over the magazines was based on a notional 10" gun, considered equivalent to the 11" German gun that was the largest expected aboard a commerce raider, while the machinery would get 8" protection. The immune zone, starting at 15,000 yards, would be based on the 60° angle of impact used for cruisers instead of the 90° angle used for battleships, thinning the required belt significantly.1 The ship was not expected to fight at long range, so deck protection, a 2" bomb deck and 4" main armored deck, was set by concerns about bombing instead of gun range. A proper TDS was impossible given the size of the ship, and a simple triple bottom was incorporated into the design instead.


Guam

This design, with 8 12" guns (two triples and a superfiring twin) came in well above the 24,000 ton target, and even going to three twins and cutting deck armor 25% couldn't bring it back down to that figure. This was seen as an unacceptable amount of firepower, particularly aft, and more studies resulted. Some looked at a triple aft and two twins forward, while others investigated if it would be possible to fit a TDS, although the loss of speed involved was considered unacceptable given the ship's role as a cruiser, likely to undertake independent operations. Admiral Stark, the CNO, also requested studies, including some with as few as four guns, in an attempt to drive size down. But some consensus was finally forming in July 1940, after at least 16 sketch designs and 6 months of confusion in high Navy echelons. The final decision was for a variant of the earlier compromise design, with 8 12" guns and a speed of 33 kts using the same machinery as the Essex class carriers. The belt was made uniform, as bulkheads to stop the magazines being penetrated by oblique machinery hits soaked up most of the savings from thinner belts, and a battleship-type fire-control tower was finally fitted to take advantage of the 12" gun's range, although they had a cruiser secondary battery of 12 5" guns and two Mk 37 directors.


The gorgeous model of Alaska on display at the Science Museum of Oklahoma.2 Note the cruiser-style single rudder, which gave these ships relatively poor maneuverability.

This decision was timely, as the fall of France to the Germans in June had opened the way for a major expansion of the USN. Previously, it had been assumed that the British would deal with the Germans, leaving the USN to worry only about Japan. Now, there was a real chance that Britain would fall, leaving the Germans in control of the combined fleets of Europe. Thus, on July 19th, America passed the Two-Ocean Navy Act, which authorized six of the new large cruisers. Detailed design began, and by the following May, enough weight was left over to replace the superfiring twin with a triple.


Alaska under air attack

The new cruisers were named after territories of the United States in recognition of their intermediate nature.3 Alaska was laid down ten days after the attack on Pearl Harbor at New York Shipbuilding Corporation,4 with Guam following on February 2nd, 1942. They commissioned in June and September 1944, respectively. They gave good service in the closing months of the Pacific War in the same roles as the fast battleships, but both decommissioned in February 1947 after less than three years of service. They remained in reserve until 1961, when they were broken up, a sad fate for such interesting ships. An argument could be made that they would have been a better choice than the Iowas for preservation, thanks to their smaller size and lower running cost, but this was probably ruled out by the fact that only two ships were available.


Hawaii in July 1946

The other four vessels were suspended along with the Montanas in April 1942, although Hawaii was put back in the plan in mid-1943 and laid down that November. The other three were cancelled that June, and Hawaii was launched two months after the end of the war. She was retained as at this point the US had only six ships capable of providing big-gun support to the carriers. Within a few years, there was obviously no need for her to be completed in her original configuration, although the existence of such a large hull had obvious appeal for conversion to other roles. Serious proposals were made for completing her as a guided-missile cruiser, which died when it was pointed out that electronic limitations would make her only slightly more effective than a converted heavy cruiser of half her size. The next plan was to make her a command ship, but this was also not pursued due to the same capability being available at lower cost. Plans continued as late as 1957, when a proposal called for her to carry 20 Polaris ballistic missiles, along with Talos and Tartar SAMs. But eventually it became obvious that the hull was a white elephant, and it was scrapped in 1959.


Guam at sea, 1944

Now that we've looked at the history of the Alaskas, it's time to return to the nomenclature question. Were they battlecruisers, as alleged by a number of their critics? In some ways, they do closely resemble Fisher's first battlecruisers. Both were built essentially as cruiser-killers with a major eye on commerce protection. But there are several key differences. Fisher's ships were the same size as contemporary battleships and carried the same guns, with a secondary mission to stand in the line of battle. None of this applies to the Alaskas, which were very clearly the products of American cruiser doctrine. They were never intended to fight capital ships, and were considerably smaller than contemporary battleships. The only post-WWI battleships of comparable size are the Dunkerques, built almost a decade earlier. The Alaskas are properly of a generation after the Iowas, and as such should be considered alongside the Montanas, which were twice their tonnage. Comparisons to the later battlecruisers fail even more clearly. Many of them were essentially fast battleships, a type exemplified in WWII by the Iowas. A few of the wartime battlecruisers departed from this mold, but the Alaskas are not particularly close to either Fisher's "Large Light Cruisers", designed apparently to fight pre-dreadnoughts in the Baltic, or to the American Lexingtons, intended as extremely fast and heavily-armed scouts. They are instead the logical extension of the heavy cruiser, and deserve to be remembered as such, and as vessels that, while too late for their intended roles, gave good service in their short careers.


1 The basic justification for this was that battleships were expected to fight broadside-to-broadside, while cruisers were more likely to engage in chases, where the target ship would be ahead of or behind the beam.

2 I have no clue why this model was included in Oklahoma's allocation of naval models, but it is unbelievably pretty. My photo.

3 The planned names were Alaska, Guam, Hawaii, Philippines, Puerto Rico and Samoa. Alaska and Hawaii didn't become states until 1959.

4 It's worth pointing out that NYSC wasn't involved with the battleship program, so these ships didn't trade off against more Iowas.

Comments

  1. November 11, 2020cassander said...

    (wasn't sure if you wanted this discussion here or the other thread, feel free to delete)

    I will fight you to the ends of the earth on this one bean, they’re battlecruisers.

    The purpose of the Alaskas was to run down and utterly dominate enemy cruisers. And, as Ian Argent points out, they’re not that far off from the Kongos in size and capability. That’s the classic BC mission, and they’re sized to do that appropriately, being substantially larger and more powerful than any existing cruiser. That’s not as big as an iowa or montana because the gap between BBs and cruisers had grown considerably in the decades since invincible. The UK’s last armored cruisers were 14kt tons, compared to 20kt for Dreadnought. to beat up armored cruisers you had to be BB sized. But by 1940, big cruisers are 15-17kt, but BBs are 55kt. Building something BB sized to beat up on them would be pointless. Besides, what what would a 1940 BB sized battle cruiser even look like?

    They were also a colossal waste of money, and demonstration of the extreme wealth advantage that the allies held over the axis, that they could afford custom extravagances like a bespoke 12 inch gun and still massively outproduce the axis in every area that mattered.

  2. November 11, 2020bean said...

    Names and roles aren't static over time, and we have to look at the Alaskas in role and design history at their time. The first generation of BCs may have been intended to beat up on ACRs, but the ACRs were practically capital ships already, and they went away because the BCs replaced them in the "fast capital ship" role. Remember that the Invincibles were authorized as "Dreadnought Armored Cruisers". By the end of WWII, the two types had merged to the point where HMS Hood, a "battlecruiser", was the largest warship in the world for most of the interwar years. The treaty heavy cruisers ultimately descended from the Hawkins class, which were big light cruisers, and not from the ACRs. The Alaska was a bigger version of that, filling a gap that had grown up because of the treaty.

    And, as Ian Argent points out, they’re not that far off from the Kongos in size and capability.

    The Kongos were very old, dating back to before WWI. This is what happens with a couple decades of ship development under your belts.

    Building something BB sized to beat up on them would be pointless. Besides, what what would a 1940 BB sized battle cruiser even look like?

    There's two within a three-hour drive of you. Go take a look.

  3. November 11, 2020echo said...

    Ok, a ballistic missile cruiser just sounds awesome, so they should have done it anyway.

    when it was pointed out that electronic limitations would make her only slightly more effective than a converted heavy cruiser of half her size.

    Guessing, but was this because the early ships were limited by the single pair of illuminators, fore and aft?

  4. November 11, 2020Ian Argent said...

    Hey, don't drag me into this : ) - or at least not on the side of calling the Alaskas anything with "battle" in their name, just because they're around the size of the Kongos.

    The design choices (as written up by Bean) including the armament and armoring schemes, are not Line-of-Battle choices. They are Enlarged Cruisers, not Pocket Battleships.

    Opinions follow: Cruisers "cruise" - they go out and about. Battleships go out looking for fights; the BB's reason for being is to find the other side's fleet and destroy it, while the cruiser's reason for being is to defend one's own vessels (both fleet and merchant) and to prey on the enemy's escorts and merchant marine.

  5. November 11, 2020bean said...

    Guessing, but was this because the early ships were limited by the single pair of illuminators, fore and aft?

    Pretty much. You can't mount those too close together without a lot of work, and the system really wasn't set up to support more than 2 per end, and no matter how big the ship is, it still only has two of those.

  6. November 14, 2020AlphaGamma said...

    Ok, a ballistic missile cruiser just sounds awesome, so they should have done it anyway.

    1957 is when the Italians started the rebuild of their 11,000 ton light cruiser Giuseppe Garibaldi, with four ballistic missile tubes (as well as a twin-arm Terrier launcher) replacing the aft 152mm turrets and I think the catapults.

    The tubes were originally designed for Polaris missiles- these were never delivered, and Italy's indigenous Alfa ballistic missile was never launched from a ship.

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