Triple-screw engines require an increase of about 6 per cent. in the engine room force; there is some added intricacy of piping and a greater number of valves, but the engineering difficulties as a ...

Working model, scale 1:12, of twin-cylinder steam driven double trunk screw engines, as extensively used for screw propulsion on the HMS 'Minotaur' and 'Northumberland' (1865-1868), construction ...