The Vengeance class was originally a class of four battle/armoured cruisers, of which only two were completed as gun cruisers, the other two being completed as the new 'ships to house, launch and retrieve aircraft'.
The aircraft carrier conversions went along in spasms as news of what was happening in Britain arrived and the designers/builders could add or subtract ideas that had or had not worked. Venomous was the first to take aircraft to sea in 1918 and trial take off and landings on a through deck with no structures to intrude. Final fit out and acceptance into the Navy did not take place until 1920 for Venomous and 1922 for Vendetta. An accident with Vendetta in 1923 nearly lost the ship and highlighted stability problems that required immediate remedying. Bulges were fitted to both ships and they returned to service in 1924.
The original armament was six 6. These were replaced as part of the stability remedies with 4.7 of the same type as refitted to the cruisers. Four high angle 4 were fitted for anti-aircraft duties. Various machine guns were added and replaced until 1936 when like the cruisers the Bofors 40mm twin mountings were fitted. The 4 guns were kept while the 4.7 were replaced one-for-one with 40mm guns. Up to 30 aircraft could be carried depending on size and type.
Displacement: 19,000 tons normal, 24,250 tons full load.
Dimensions: 643 x 84 x 26 feet
Machinery: 2 shafts, turbines, 80,000shp
Speed: 29 knots
Endurance: 9,500 miles at 14 knots
Armour: 3 belt, 2 deck.
Armament:
6 x 6 (6x1) replaced by 4.7 1923-24
4 x 4 AA (4x1)
Aircraft: 30
Crew: 900
Displacement: 19,850 tons standard, 26,400 tons full load
Dimensions: 643 x 84 x 26 feet
Machinery: 2 shafts, turbines, 80,000shp
Speed: 28 knots
Endurance: 10,000 miles at 14 knots
Armour: 3 belt, 2 deck.
Armament:
4 x 4 AA (4x1)
12 x 40mm (6x2)
Aircraft: 30
Crew: 950