SS Great Britain, propeller and rudder. Francis Smith patented the screw propeller in 1836. and Brunel changed the design of the engine of his Great Britain to fit one. The rudder also was new, being pivoted not at the leading edge but near the centre, giving a lightness of touch to the steering. Like the rudder, the propeller, 15 ft 6 in (4.75m) diameter, is a reconstruction and forms part of the restoration of the ship, now resting in the dock from which it was launched at Bristol in 1845.