Ordered and laid down in 1918, the Gerlache class was to have twelve units originally. This was reduced to six with the end of the war in sight and reduced again to three on the Armistice. These were to be an extension of the previous Bjaaland class with a fourth twin 6" fitted forward. The speed was originally to be the same as the Bjaaland - 30 knots. This was increased to 32 knots, then 34 knots to counter and catch the fast minelayers that had been built to lay offensive minefields around the coasts of Antarctica. This requirement made the ships bigger and bigger to fit the machinery power required.



These were big ships. Longer than the Manahan class armoured cruisers, but half their displacement. On full speed trials they exceeded the speed requirement but were credited with 34 knots at standard displacement. Like all ships these three would be a couple of knots slower at full load displacement. These ships were the greyhounds the Navy had wanted. In the above drawing I show the catapult and aircraft but this was not fitted till 1926. Same with the two quad 2 pounder mountings beside the bridge, these were not available to be fitted till 1928, other larger ships got priority for the new weapons.



The three Gerlache class ships spent their careers as squadron flagships with a Commodore or Rear Admiral in command. Firstly with members of the Bjaaland and Bransfield classes, while those cruisers were still armed with 6" guns, then later with the Hornby class light cruisers. Between 1938 and 1940, many changes took place aboard the Gerlache class. Radar started appearing, the 4" were paired and shielded, one set of torpedoes was removed to aid stability with the added topweight. the single 2 pounder guns were removed and replaced with a quad 2 pounder aft and single 20mm wherever there was space. 1942 and the remaining set of torpedoes and the aircraft handling facilities were removed in the forever battle against topweight.

 

Displacement	7,500 tons standard, 9,800 tons full load
Length	570 ft
Breadth	56 ft
Draught	19 ft
Machinery	4 shaft, steam turbines, 100,000ihp
Speed	34 knots
Range	7,000 miles at 12 knots
Armour	3" side, 2" deck
Armament	As completed 8 x 6" (4x2) 4 x 4" AA (4x1) 12 x 2pd AA (2x4, 4x1)	Refits to 1940 8 x 6" (4x2) 8 x 4" (4x2) 12 x 2pd (3x4) 16 x 20mm (1x2, 14x1)
Aircraft	1 (no hangar)	Removed 1941
Torpedoes	16 x 21" (4x4)	8 x 21" (2x4)
Complement	580	600
Notes	General Gerlache - Alpha River Onyx River