text:  The first ocean @-@ going ironclads carried masts and sails like their wooden predecessors , and these features were only gradually abandoned . Early steam engines were inefficient ; the wooden steam fleet of the Royal Navy could only carry " 5 to 9 days coal " , and the situation was similar with the early ironclads . Warrior also illustrates two design features which aided hybrid propulsion ; she had retractable screws to reduce drag while under sail ( though in practice the steam engine was run at a low <unk> ) , and a <unk> funnel which could be folded down to the deck level . 
  