The Minotaur-classarmoured frigates were enlarged versions of HMS Achilles with heavier armament, thicker armour, and more powerful engines. The ships of this class were unique among ironclad warships in possessing on completion five masts, named fore-, second-, main-, fourth- and mizzen.
They were originally intended to mount forty Armstrong110-pounderbreech-loading guns on the main deck, with ten more on pivot mountings on the upper deck. The failure of these guns in service led to a complete re-evaluation of their armament, with a concomitant delay in the arming of the whole class. The ships were armed with a combination of 9-inch muzzle-loading rifles (MLR) on metal carriages and 7-inch MLRs on rope-worked carriages. In a moderate swell these 7-inch guns were virtually unworkable, making the Minotaurs both the heaviest and the worst armed of the Victorian battleships.
The Minotaurs were poor sailors, never exceeding a speed under sail of about 9.5 knots (17.6 km/h; 10.9 mph) with all sail set and a favourable wind. They were, in spite of the number of masts they exhibited, the most sluggish of all British ironclads under sail. They were regarded as good sea-boats, and were considered to be among the steadiest ships in the battle-fleet. They were slow in manoeuvre under hand-steering, but were regarded as good after steam steering was fitted.