Designed by Edward Reed,[2] the Royal Navy Director of Naval Construction, they were equipped with a ram bow.

[2] The hull was of wooden construction, but they were the first class of sloops to incorporate a form of composite construction; they had iron cross beams while retaining wooden framing.

[2] Propulsion was provided by a two-cylinder horizontal single-expansion steam engine by Ravenhill, Salkeld & Company driving a single 15 ft (4.6 m) screw.

[2] The class was designed with two 7-inch (6½-ton) muzzle-loading rifled guns mounted on slides on centre-line pivots, and two 64-pounder muzzle-loading rifled guns on broadside trucks.

Dryad, Nymphe and Vestal were rearmed in the early 1870s with an armament of nine 64-pounder muzzle-loading rifled guns, four each side and a centre-line pivot mount at the bow.