She was one of two sister ships secretly ordered from the John Laird Sons & Company shipyard in 1862 by the Confederate States of America.

The hull was divided by 12 watertight bulkheads and the ships had a double bottom beneath the engine and boiler rooms.

The engines produced a total of 1,450 indicated horsepower (1,080 kW) which gave the ships a maximum speed of 10.5 knots (19.4 km/h; 12.1 mph).

[4] The ships carried 336 long tons (341 t) of coal, enough to steam 1,210 nautical miles (2,240 km; 1,390 mi) at 10 knots (19 km/h; 12 mph).

Wivern was the first ship to have tripod masts to reduce interference with the firing arcs of the gun turrets.

[5] No ordnance had been ordered by the Confederates before the ships were seized in 1863, but in British service they mounted a pair of 9-inch rifled muzzle-loading guns in each turret.

The inside of the turret was lined with .5 inches (12.7 mm) of iron boiler plate to which T-shaped beams were bolted.

Yet on one occasion her behaviour at sea was so bad that she had to be brought head to wind in order to prevent her shipping large, and, of course, dangerous, quantities of water, the extreme angle of roll rising to 27 degrees each way.