Andrew Noble. Rendel gunboats In 1867 Armstrong signed an agreement with a local shipbuilder, Dr. Charles Mitchell, whereby Mitchell's shipyard would build warships and Armstrong's company would provide the armaments. George Rendel was put in charge of the new venture and he designed the early ships produced by it. These were the Rendel gunboats (or "flat-iron gunboats" after their physical similarity to a contemporary flat iron) produced for the British Admiralty as well as for Italy, Brazil and Chile. The first of these was HMS Staunch, delivered in 1868. Unarmoured cruisers Armstrong's Elswick yard became well known for its construction of cruisers, and Rendel designed many of these. He designed a series of 1,350 ton unarmoured 16 knot cruisers for the Chinese (Chaoyong and Yangwei) and Chilean navies. Protected cruisers Following this, together with Armstrong, he designed the world's first protected cruiser, the prototype being the . The design had an arched steel protective deck running from stem to stern just below the waterline. All of the vital parts of the ship were placed below the protective deck. The ship also had cork-filled cellular compartments to aid with buoyancy. The Esmeralda was built for Chile, and was later sold to Japan and became the Izumi. The Japanese navy in particular took several Rendel-designed cruisers, with which they defeated the Russian navy at the Battle of Tsushima in 1905. Forced draught Rendel and Alfred Yarrow pioneered the use of forced-draught fans in boiler rooms, significantly increasing the power of marine steam engines at minimal cost in weight or volume. Naval guns Rendel worked on the design of large naval guns, using hydraulics to reduce the number of men required to work the guns and the space required. This was first tried on HMS Thunderer, which was able to have 38-ton guns fitted, instead of the 35-ton guns originally planned. His hydraulic systems were subsequently used in all Royal Navy ships as well as the ships of several foreign navies. HMS Inflexible In 1871 Rendel was appointed a member of the British government committee on warship design. He played a major role in the 1877 design of the innovative HMS Inflexible, which was notable for being the first major warship to depend in part for the protection of her buoyancy by a horizontal armoured deck below the water-line rather than armoured sides along the waterline. She was packed with other new features: