Note 261 — Chapter VI

On arriving in shallow water or nearing a port the screw is raised, so that the bottom of it is above the level of the keel, and when the blades require examining or replacing, the shaft can be raised still higher, thus exposing the boss and allowing ready access when the ship is in light trim. The last two lengths of shafting are connected with an universal joint which works in a chamber in the after end of the tunnel and is at all times accessible to the engineers. The bush is guided by two cheeks on the stern-post, and raised by means of rods with gearing on the middle deck either by a steam-engine or by a hand winch placed on the upper deck, additional power being always at command through the medium of the capstan. The want of the customary keel pieces joining the inner and outer stern-post conveys an appearance of weakness, but this is amply compensated by the increased width and additional thickness at the head of the screw aperture; and the centre of effort of the rudder being raised above the ordinary height. A false foot is fitted to the bottom of the rudder-post and this foot can be readily removed, allowing the screw boss to be changed without disturbing the shaft, which is another very important feature.—Ibid., 20th November, 1874.