A few ways to get Germany some ships
Battleships Sachsen and Wurttemberg, and battlecruisers Graf Spee and Mackensen were already launched, and so not occupying slipways. Of the otehr two Mackensens, Erstaz Freya (to be named Prinz Eitel Freidrich) was launched in 1920 to clear the slipway, while Ersatz A (expected to be named Furst Bismarck) was broiken up on the slip.
Any of them would be a rusted hulk by the time Hitler came to power, if they were just left there.
That said, I've got a few schemes to preserve one or more in an A/H scenario, with a POD no earlier than Novemver 11, 1918.
Option 1.
Greece convinces the Allies to make Germany complete one or more of the battlecruisers, or better yet, Ersatz York, as replacement for Salamis, which is a rusted hulk after years of sitting in the yard. The cost is credited against German reparations. (If Greece was interested in a battlecruiser instead of a battleship, I think most people would rather have a German design.) Perhaps a new battleship or battlecruiser was part of the deal under which Greece joins the war, althought this requires an earlieer POD.
Work on the ships progresses slowly, as money is short, and Greece has no imeadiate threat, and so modifications are incorporated into the design. Delays occurr--and the whole project can't even start until the treaty is finalized. Hitler ends up offering to buy the ships when he comes to power, and they're completeing fitting out--or just takes them.
This also gives Germany the capability of manufacturing big guns and heavy armor--something useful to Germany.
Option 2.
One or more of the ships are converted to civilian use. Thios isn't as far-fetched as it might seem, other capital ships were converted, or plans existed to convert them.
Examples:
Italia, built 1885, converted to cereal carrier 1917.
Italy's Francesco Carraciolo (laid down 1914) was sold while partially complete to a shipping firm for conversion to a high speed passenger-cargo ship.
In addition, there were plans post-war to convert 3 of the Mackensens to tankers, but they were scrapped (along with the ships) for economic reasons. Suppose the plans had been carried out, while the armor was stockpiled somewhere. At least one, and possibly more (I have no information on just how many) of the guns destined for Saschen and Wurtenburg were test fired by Germany in 1938 while preparing the Bismarck's guns. Perhaps enough were stockpiled to re-arm one of the converted battleships...
If the conversion was done with an eye towards re-converting them, there would be some time savings possibly-but Germany gets an obsolete ship--bur one that could be brought up to modern standards the way the rest of the world's battle line was durring the battleship holiday.
There's a few options for getting the ships to survive long enough. Perhaps if the Great Scuttle didn't occur, Germany would have been allowed to keep 4 modern captal ships. If so, and if the Washington 20 year clause is adopted, then Germany gets to build 4 shiny new battleships for completion in 1934-1937 as Konig, Hindenburg, Baden, and Bayern reach the 20 year mark--earlier if 2 Konigs replace the 15" ships.
If Germany has four battleships/battlecruisers, perhaps the Washington Treaty gives the US and Britian 20 ships instead of 15, and a corresponding increase for the rest of the signatories, giving Britain a reason to sign on. She had to, anyways, as she couldn't afford the G3's and N3's.
Knowing Hitler, the completion of the new ships is delayed--and when he renounces Versailles, the scrapping of the older ships hasn't started, while the new ones are just about to enter service. Voila--8 capital ships. (I chose to allow Germany four, as ships of the time often opperated in groups of four.)
With legitimate reason to work on warship design, Germany may well have better ships than she did historicly--German ships of World War Two had some severe weaknesses, although this is not the forum to critique the designs.
Dual purpose guns, better armoring schemes, and more reliable engines could come out of extensive tests on old pre-dreadnoughts.
There's a few ways to keep some of the ships, or get Germany new ones earlier and better. I don't claim they're probable--in fact, they seem to be long shots all--but I think they're all possibilities, with the right POD.