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It would be great to see some of this stuff. Does Downfall already cover some of this territory?

I would do a late start with an ahistorical reason for the war to go late. Say the three carriers were stting pretty in PH on Dec. 7 and it delayed the war by a year. Thus, you could do a June 1945 start with Saipan, Guam and Tinian still in Japanese hands.

Cheers,
CC

On average, 3 liberty ships finished production each day with the average build time of 42 days nationally and 2 weeks at Kaiser shipywards. Kaiser reduced the build time by replacing rivets with welding (which was new at the time and until the kinks were fixed resulted in some ships in the north Atlantic convoys literally breaking in half).

The fastest liberty ship built was the Robert E. Peary which was built in 4 days 15 hours and 29 minutes as a publicity stunt at Kaiser's Richmond shipyard.

The implication of your post seems to be that the structural failures were the direct result of the widespread applicsation of welding to construction of the Liberties. I think that may be misleading, since from what I have read the problem arose not from the adoption of welding techniques but from greater 'notch brittleness' of American mild steel used for shipbuilding compared with British steel, which tended to have a higher carbon to manganese ratio. In other words the primary reason for such structural failures was metallurgical.

The significance of welded construction lay in the fact that welded seams provided an uninterrupted medium through which a crack, once started, could continue to propagate. Part of the solution to the structural failure problem consisted of riveting crack arrester strips to decks. Being attached by rivets, these strips would be unaffected by cracks propagating through the underlying deck.

The Bethlehem-Fairfield yard at Baltimore was the only major producer of Liberties that used riveted plate seams, and its output suffered a lower ratio of major structural failures than other yards. Probably this was primarily due to such rivetted seams operating as effective crack interrupters.

The Liberties were not the only ships to suffer major structural failures. At least two T-2 tankers, Esso Manhattan and Shenectady, suffered major damage in which the hogging effect upon their hulls was such as to induce an angle of about 15-20 degrees between the forward part and the aft.

ORIGINAL: Local Yokel
The Liberties were not the only ships to suffer major structural failures. At least two T-2 tankers, Esso Manhattan and Shenectady, suffered major damage in which the hogging effect upon their hulls was such as to induce an angle of about 15-20 degrees between the forward part and the aft.

Nineteen US welded ships either broke in half or broke their backs and had to be abandoned from ’38 to ‘48: nine T2 tankers, two ‘other’ tankers, seven Liberty cargo, one LST conversion. Some foreign (British and Canadian) built ships too.

Everything you never wanted to know about welded vs riveted ship construction, specific Liberty ship construction details, causes of hull plate fractures, all this and T2 tankers, too.

http://www.shipstructure.org/list_reports.pl

Two very nice overviews from 1952 are : SSC-62 : Structural Studies Related to Ship and Ship Components For Determining Loads and Strains On Ships At Sea, by J.H.Evans, MIT, and SSC-63 : Welded Ship Failures, H.G.Acker, Bethlehem Steel. Both are reports prepared for the NRC’s Committee on Ship Structural Design.

Quite extensive studies of welded vs riveted construction in bulk cargo vessels and liquid carriers. Includes extensive analyses of Liberty ships as well as other contemporary US and foreign bulk carriers, and analysis/comparison of primarily T2 tankers constructed by both techniques.

Neat stuff.

Some of those SSC reports are a bit deep for me, but SSC-52 and SSC-63 are eminently readable - Thanks, JWE!

US Naval Research Lab. Report 5920 may also be of some interest, and deals in part with the fate of oiler USS Ponaganset (a T2 design) which, in 1947, was completely bisected by a crack initiated by the striking of an arc at the base of a bracket supporting a chock - imagine the thoughts of the welder as the vessel split in two beneath him!

<edit> Substituted link to a full copy of the report - patience required; it takes a while to load </edit>

Thanks JWE

Ya'll are very welcome. Glad I could help. LY, am familiar with Report 5920, fun stuff, and it comports nicely with the other failure details. But I sure wouldn't have wanted to be that welder [:D]

Going back to the OP topic, There were several hundred German/Danish/Dutch ships captured in various North Sea and Baltic ports that were eminently suitable for operational use. These were contemporaneously known as the Hansa ships. Taken in hand, mostly by MOWT, they were being outfitted for use in the Pacific. Don Bowen has the full list, including relevant specs, for each such vessel being outfitted.

The Maritime Commission and the Planning Board, decided in early '44 to stop production of EC-2 models in favor of VC-2s. Where applicable, US wartime production would be of models and types that would easily adaptable to post-war commercial service; otherwise, an utter waste of resources. Most shipyards had already geared up to produce VC-2s, and the remaining yards were either following or being phased out.

There should be no additional EC-2 production. Continued VC-2 production is a possibility. Incorporation of the Hansa fleet is a necessity.

ORIGINAL: Local Yokel

The implication of your post seems to be that the structural failures were the direct result of the widespread applicsation of welding to construction of the Liberties. I think that may be misleading, since from what I have read the problem arose not from the adoption of welding techniques but from greater 'notch brittleness' of American mild steel used for shipbuilding compared with British steel, which tended to have a higher carbon to manganese ratio. In other words the primary reason for such structural failures was metallurgical.

No the implication of my post was that liberty ships in the North Atlantic did have structural failures that were attributable to the welding which was solved, I believe, by simply welding a iron strip along the hull.

I probably over-simplified by referring only to the metallurgical properties of the steel used, since low temperature seems also to have been a significant factor, both in initiation of the crack and the ability of plates to arrest it. Obviously the presence of welded seams was also a precondition of the failures under consideration. However, leaving aside the case of Ponaganset where the striking of the welder's arc initiated the failure, I was not aware of welding itself having been the main cause of such failures. Is there something I have missed here?

ORIGINAL: Local Yokel

I probably over-simplified by referring only to the metallurgical properties of the steel used, since low temperature seems also to have been a significant factor, both in initiation of the crack and the ability of plates to arrest it. Obviously the presence of welded seams was also a precondition of the failures under consideration. However, leaving aside the case of Ponaganset where the striking of the welder's arc initiated the failure, I was not aware of welding itself having been the main cause of such failures. Is there something I have missed here?

Oversimplification for both of us. Sources I had didn't refer to metallurgical failures but just the catastrophic failures which caused ships (which they always seemed to stress being welded over rivited ships) to break apart and the "final" fix.

Of course, another relevant factor was design detail such as the squared-off corners of the holds and accommodation hatches that provided stress concentration points at which cracks were likely to start. A consideration that seems to have eluded the designers of the de Havilland Comet. [:(]

The vital point about the cure of applying crack arrester strips is that they were rivetted in place rather than welded. This introduced a discontinuity in the material through which the crack could not propagate.

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