Displacement: (700,000 tons planned) 462,750 tons light; 484,920 tons standard; 560,057 tons normal service; 617,927 tons full load

Dimensions:
Length: 2,000’ (609.60m)
Beam: 300’ (91.44m)
Draft: 55’ (16.75m)

Armament:
Main: 8 x 31.5” (80cm) Gustav siege guns (4 x 2)
Secondary: 12 x 9.45”/73 (24cm) Long Range AA guns (12 x 1)
Tertiary: 24 x 5.04”/60 (12.8cm) AA guns (12 x 2)
Light: 5.5cm/77 Gerat 58, 30mm AA guns
(Broadside = 131,574 lbs/59,631 kg)

Aircraft: 15 aircraft

Armor:
Belt: 14.96” (380mm)
Deck: 14.96” (380mm)
Turrets: 25.96” (660mm)
Conning tower: 24.8” (630mm)

Machinery: 8 shafts, (480,000 shp planned) 498,735 shp/372,057 kw
Performance: 28 knots
Range: 30,000 nm @ 20 knots
Complement: (5,000 planned) 10,236 – 13,307

Distribution of weight:
Armament: 16,425 tons = 2.9%
Armor: 158,660 tons = 28.3%
Machinery: 11,931 tons = 2.1%
Hull, fittings & equipment: 274,955 tons = 49.1%
Fuel, ammunition & stores: 97,307 tons = 17.4%
Miscellaneous weights: 750 tons = 0.1%

This is a 700,000 ton German battleship built to carry a battery of eight 80 cm/31.5 guns, the siege gun Gustav. This is strictly a flight of fancy taken from remarks made by Hitler that he wanted to mount 80 cm guns on the H-class. It was estimated that it would take a 700,000 ton ship to mount them.

Rate of fire for the main battery would be quite slow, one round per gun every five minutes or more while the AA defense would be much more rapid. The AP shell weighed over 15,000 lbs with 441 lbs of burster while the HC shell weighed over 10,000 lbs with 882 lbs of burster.

The 24 cm/73 AA armament was based upon a Kriegsmarine late war study to develop a land based high altitude gun firing a 300 plus pound shell up to 59,000 feet. It is possible that a 700,000 ton ship could carry twelve of these in single double purpose mounts, partly to make up for the slow rate of fire of the 80cm main battery and to engage cruisers.

The 5"/60 were probably Germany's best AA weapon at the end of the war and would have served this mastodon well.

The 80 cm weight of shell is based upon reality. Initially, the 80cm gun was intended to bombard the Maginot Line but as it was not completed in time, it was intended then to use it against Gibraltar. As Spain would not give right of passage to German invasion forces, the Wehrmacht took the gun(s) to Russia and bombarded Sevastapol and possibly Leningrad. The Gustav fired approximately 46 rounds in two days and inflicted incredible damage.

The turrets on this ship are so huge in order to provide sufficient room to handle absolutely giant shells and hold the extremely extensive and strong hoist and rammer facilities needed to fire the shells.

There is no detail information regarding the ship’s power plant. The total SHP required for a ship of this size dictated at least 8 shafts. Based on the extended range of these ships it would appear that a portion of the power plant was diesel.

This design does not ‘compute’ when plugged into Springsharp. The numbers in the weight distribution are extreme estimates.

This drawing is basically a 1:x upscaling but a 600 m BB could/should be completely different.

I am strongly convinced that the H44 was already too much as standard BB while the H45 could/should be something radically different.
The starting point are only the basic Hitler's specs(whishes): from there several solutions/drawings are feasible.
I'll not follow the web skecth but I'll workout a personal solution.
It means that this will be the perfect target for any type of critics: I'll be open to accept and/or discuss all the constructive ones.