Ocean liner converted to aircraft carrier?

Discussion in 'Alternate History Discussion: After 1900' started by I want to learn, Apr 12, 2015.

  1. I want to learn Well-Known Member

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    What if some of the large ocean liners such SS Normandie or SS Breman of the 20s and 30 were converted to aircraft carriers for use in World War Two? They were large and fast vessels. Japan laid down the Hiyo class as ocean liners, I don't believe they ever served as such. Italy started converting SS Roma, but never finished her. I know some of the ocean liners served as fast troop carriers, but others were laid up.
     
  2. wietze Figment of my own Imagination

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    normandie sure was very fast, although i do think she would have been much more useful as a fast troop carrier (the us was doubting between converting her to troop carrier or to aircraft carrier)
     
  3. Mike Stearns Member

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    I agree. Trooping duty is a far better use for an Atlantic greyhound like the Normandie. The Cunard Queens supposedly shaved something like an entire year off the length of the war all by themselves because they were too fast to be caught by U-boats. There's also the fact that you'd have to remove most or maybe all of the superstructure, which there's a lot of on a big liner and that'll take time.
     
  4. I want to learn Well-Known Member

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    If you take all the things that supposedly shortened World War Two by at least a year, and did away with them, we'd still be fighting the Nazis today. :p ;)

    Besides, Normandie never functioned as an Atlantic troop transport, nor did the Breman or Europa. They could have begun conversions at the start of the war, when it was realized they would be unable to perform their designed roles.
     
  5. Hammerbolt Well-Known Member

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    The Normadie was french, so only they could have decided. And such a convertion would take too long, cost too much, and ocupy a large shipyard, allready full with orders for proper warships. And the Bremen was german... which means the idea would "run into" Goering... who would oppose it, as he did the carrier.
     
  6. CalBear Your Ursus arctos californicus Moderator Moderator Donor

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    Japanese did this, although the ships were designed with conversion in mind (IJN paid better than half the construction cost), as noted with the Hiyo class. They were far more robust than the normal civilian liner (double hull, provisions for additional bulkheads and bracing, more fuel capacity, etc.).

    The problem with a conversion of pure civilian vessel is the internal volume is all wrong, the construction is much lighter, both of the hull itself as well as compartmentalization, and machinery is not designed for the sort of abuse that warships encounter on a regular basis.

    What will hurt a warship will sink a civilian vessel of two or three times the size. A WW II 12,000 ton full load cruiser would have better resistance than a liner the size of the Normandie (70,000 tons), as would a 17,000 ton carrier of the Yorktown class. The amount of time and effort needed in the yard to have her razeed and provide space for a hanger and avgas fuel tanks would likely be greater than that to build an actual proper carrier.
     
  7. fastmongrel Well-Known Member

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    Dont think the big liners would have made good carriers they all had very short legs, basically enough bunkerage to get from one side of the Pond to the other.

    Carriers need long range because they spend a lot of time steaming in the wrong direction to launch or land.
     
  8. Mike Stearns Member

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    No she didn't. She was impounded by the US government following the fall of France in 1940 and was in the process of being converted for trooping duty when careless workmen accidentally started a fire and she sank at her dock, as a result. Based on the example and experience of the two Cunard Queens, the only other ships big enough and fast enough to rival the Normandie in peace time, she would have a formidable war asset. Don't forget that the Queen Mary and the Queen Elizabeth were capable of embarking an entire division at once.
     
  9. fscott As you age things get gayer

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    December 1942, Queen Mary carried 16,082 American soldiers and routinley carried 15k not only from the US but also Australia maybe SA also as that was a fueling stop. So each of the Queens carrying 15k troops at just over 30 knots compared with the Liberty troop ships which in the Southwest Pacific were turned into makeshift troop transports for New Guinea operations by installing field kitchens on deck, latrines aft between #4 and #5 hatches flushed by hoses attached to fire hydrants and about 900 troops sleeping on deck or in 'tween deck spaces. While most of the Liberties converted were intended to carry no more than 550 troops thirty-three were converted to transport 1,600 on shorter voyages from mainland U.S. ports to Alaska, Hawaii and the Caribbean at 11 knots. The Queens could out run submarines the Liberty ships can't. Carrying extra troops made them top heavy and a wave hit the side of the QM and almost rolled it over. A serviceman later wrote the Poseidon Adventure.
     
  10. docfl dazed and confused

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    The Germans did start planning on converting Europa and Bremen to carriers. Never did get past planning stage. Bremen was destroyed, Europa was given to the French after the war.
     
  11. Zheng He Well-Known Member

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    Were some of the early escort carrier or MAC conversions smaller liners?
     
  12. Perky50 I have my moments

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    .... I think if one was to look they would find that HMS Argus sprang forth from the uncompleted Italian Liner Conte Rosso ... just sayin' ...:)

    ... back on topic ...
    I'd be thinking along the lines of most others here arguing against the conversion idea .... the demand on the existing large, fast liners for troopers would preclude them from conversion to carriers.

    In most of the cases where liners were indeed converted to carriers, the liners used were not in the same category for speed or size of the Blue Riband elite.
     
  13. TFSmith121 War is the remedy that our enemies have chosen ... Banned

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    In the 1920s and 1930s versions of WP Orange, before

    In the 1920s and 1930s versions of WP Orange, before the RAINBOW plans, the USN's detailed plans for mobilization of the US Merchant Marine included liner conversions.

    From the 1920s onward, the large fast liners built (or rebuilt) with USG funds (first by the USSB, then by the US Maritime Commission) had various earmarks for mobilization; at times, no less than a dozen large liners (including the 55,000-ton SS Leviathan, commissioned in 1911 as the German liner Vaterland and used under the US flag as a troopship in WW I and then converted to a liner - essentially a near-total rebuild and under the US flag until the mid-1930s, and capable of 28 knots burning oil). Unfortunately, she was completely uneconomic to run, and was scrapped (in the UK) in 1938...

    Others included the modern (~1930) sisters Washington and Manhattan; California, Pennsylvania, and Virginia; and Malolo (half-sister), Lurline, Monterey, and Mariposa.

    All the 1930s era ships were built with some military features as potential troop transports, and with at least some basic planning for carrier conversions; these were designated as XCVs, and the seven smaller ships would have approximated Ranger/Wasp in tonnage and would have carried a smaller but balanced air group of 18 fighters, 18 scout/dive bombers, and 18 torpedo bombers. Manhattan and Washington were larger (~22,000 tons vs. ~17,000-18,000) and faster (22 knots vs 18 knots) and, if converted, might have approached a Yorktown in size and a Ranger/Wasp air group (36 VF, 36 VSB).

    In the event of a Pacific War that broke out before the expiration of the Washington treaty, they would have been very useful ships as carrier conversions; as it was, given the passge of the Vinson-Trammel acts and the need for shipyard resources for the Essexes (and then the Independence conversions) and especially the Two Ocean war and the needs of BOLERO and (as envisaged) ROUNDUP, they were more useful as troopers - these ships (along with USS West Point/SS America) are why the British 18th Division got to Singapore, for example.

    In 1940-41, the USN also looked at Lafayette/ex-Normandie and the John Ericcson/ex-Kungsholm, but again, using them as troopers made more sense.

    The need for fast carriers was met by the 24 Essexes and the nine Independences; the need for auxiliary carriers was met by the CVEs, both the C3 and T3 hulls and the Kaiser P2s.

    The British, who had more liners than anyone else in the 1930s and 1940s, actually managed one such conversion, the Pretoria Castle, which despite her size was not actually all that more impressive in terms of capabilities than the handful of British CVEs converted from cargo or passenger-cargo ships.

    Going back farther, there was Argus and the first Campania, but they both illustrate the problems with trying to convert ships designed to carry people into ships designed to carry things...freighters and tankers were actually better bets for successful carrier conversions than liners, generally.

    Best,
     
  14. zoomar Curmudgeon

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    IN "US Aircraft Carriers", doesn't Friedman describe a concept design the US developed for high-speed liners that could be "relatively easily" converted to a fleet aircraft carrier or am I dreaming? It would have been far better suited for fleet use that the IJN's Hiyo, which was too slow. The design was never built as either a liner or carrier.
     
  15. TFSmith121 War is the remedy that our enemies have chosen ... Banned

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    Yep, it was an outgrowth of the XCV concept


    Yep, it was an outgrowth of the XCV concept.

    Best,
     
  16. Mike Stearns Member

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    That line of thinking also supposedly influence the design of the United States, which was designed for a rapid conversion from liner to troop ship.
     
  17. Grey Wolf Writer, Poet, Publisher, Cat-sitter

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  18. RJGFox Well-Known Member

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    Liner Roma became Aquila, and her sister Augustus became Sparviero - not a great design. Would have been better to duplicate Aquila I guess.
     
    Last edited: Apr 13, 2015