The Washington Treaty allowed for building of aircraft carriers. Antarctica had 90,000 tons for new construction that could be split into whatever sizes it wished. Even six by 15,000 ton ships was contemplated. Antarctica had time to trial the four carriers they had in service to get a feel for the new ship type and what it could do. New construction was to be three 30,000 ton aircraft carriers. The trials had shown the more aircraft that could be got to sea the more chance they had of being effective against an enemy. The Amundsen had shown that too many 'warship' features were not conducive to the maximum amount of aircraft that could be fitted in the hangar(s).



The first of the three ship class was laid down in late 1925 with completion expected in 1929. The Senate funded a new ship every two years, with completion for the next two in 1931 and 1933. They were to be big ships, with a length of over 800 feet and a breadth over 100 feet. During the mid 1930's the armament started changing quite drastically with the removal of the low angle 4.7" and their replacement with the new 4.5" dual purpose gun system. This meant that the 4" AA were no longer required, either, and these were replaced with four octuple 2 pounder. 20mm Hispano-Suiza mountings started appearing, and more and more space was given over to AA weaponry. 1942 and the 2 pounder and 20mm are replaced with quad and twin 40mm. Within six months radar predictors for these weapons also start requiring space and personnel. Electronic equipment was in full proliferation mode with updates for aerials and equipment arriving aboard any time the ships reached port.



It is the aircraft in 1942 that had been designed to give the Antarctican carriers the edge. The new generation of fighters, dive bombers and torpedo / bombers were, for twelve months, the best around. Then, of course, the rest of the world caught up and something new was required to put the Antarcticans back in the lead of aircraft development - jets.

 

Displacement	31,500 tons standard, 37,000 tons full load
Length	862 ft
Breadth	106 ft hull (120 ft over sponsons)
Draught	31 ft
Machinery	4 shaft, steam turbines, 120,000shp
Speed	30 knots
Range	12000 miles at 14 knots
Armour	3" side, 3" deck
Armament	As completed 12 x 4.7" (12x1) 8 x 4" AA (8x1) 24 x 2pd AA (6x4)	1941 12 x 4.5" (12x1) 56 x 2pd (4x8, 6x4) 16 x 20mm (16x1)
Aircraft	90	98
Complement	2350/2500
Notes	Captain Furneaux - Admiral Ellsworth - Commodore Kagge -

The same 4.5" DP AA guns were deployed all over Antarctica as those fitted to the Furneaux.
As can be seen the gun can be loaded at full elevation. These are early fixed ammunition guns.
Later models had bag and shell ammunition which was better for crew fatigue.