 Originally designed with three masts , Northumberland was fitted with five masts until her 1875 – 79 refit when two were removed and she was re @-@ rigged as a barque . Northumberland only made 7 knots ( 13 km / h ; 8 @.@ 1 mph ) under sail , mainly because the ship 's propeller could only be disconnected and not hoisted up into the stern of the ship to reduce drag , the worst speed of any ironclad of her era . Admiral George A. Ballard described the Minotaur @-@ class ships as " the dullest performers under canvas of the whole masted fleet of their day , and no ships ever carried so much dress to so little purpose . " 
