The ships were wooden-hulled, with both steam power and sails, and of shallow draught for coastal bombardment in the shallow waters of the Baltic and Black Seas during the Crimean War.

[2] One of the vessels of the class, HMS Surly, cost £9,867, of which the hull accounted for £5,656 and machinery £3,298.

[3] Half of the ships had two-cylinder horizontal single-expansion trunk steam engines, built by John Penn and Sons, with two boilers.

The other half had two-cylinder horizontal single-expansion direct-acting steam engines, built by Maudslay, Sons and Field, with three boilers.

Both versions provided 60 nominal horsepower through a single screw, sufficient for 7.5 knots (13.9 km/h; 8.6 mph).