They were a revised version of an 1874 design by the Royal Navy's Chief Constructor, William Henry White, the Osprey-class sloop.

The Nathaniel Barnaby design was a development of William Henry White's 1874 Osprey-class sloop.

The graceful clipper bow of the Opsreys was replaced by a vertical stem and the engines were more powerful.

Power was provided by three cylindrical boilers, which supplied steam at 60 pounds per square inch (410 kPa) to a two-cylinder horizontal compound-expansion steam engine driving a single 13-foot-1-inch (3.99 m) screw.

[1] All the ships of the class were provided with a barque rig,[1] that is, square-rigged foremast and mainmast, and fore-and aft sails only on the mizzen mast.