1851 Great Exhibition: Official Catalogue: Class VIII.: E. J. Carpenter
194. CARPENTER, E. J., Capt., Senior United Service Club — Inventor and Patentee.
Duplex rudder and screw propeller. — The engraving represents a stern view of a vessel with two rudders and two screw propellers, fitted in new positions for improved steering and propelling. From the midship section of the vessel to the stem, no alteration is introduced into the form of the hull; but abaft this point they commence. First, the keel, with the dead wood, stern-post, and rudder, are removed, and the flooring above receives a suitable form for strength. Two additional keels lie in a line parallel with the former keel, but placed at a distance of two or more feet, according to the size of the vessel, on either side of it, terminating at the midship section in the fore-part, and in a line with the former stern-post in the after-part. Framework is carried down to these keels, leaving a free channel for the water to run between them in the direction of the midship keel. A stern-post is placed at the end of the additional keels, and upon each of them hangs a rudder.
A screw-propeller works in an orifice in each framework, on the common arrangement. One of the propellers is a little more aft than the other, to allow full play to both, and yet economise space in the mid channel.
The appearance of the vessel in the water is not altered in the side view, neither is it much changed in the stern view.
The consequence of this new arrangement is, that the rudders and propellers are acting with double effect in each case. The rudders are receiving an increased power, because the impact of the water upon them takes place at an angle which is constrained by the situation of the keels, and which is the most favourable that can be had. The two propellers, also, revolving as they are in water confined in a limited space, are working to considerable advantage. The effect actually produced is, that, when required, a vessel can be turned about in nearly half the space that a single rudder can turn it, and the two propellers will give a proportionate increase of speed.
The advantages gained by the new construction of the vessel are considerable. There will be more strength, more bearings in the run, and more breadth for cabin room. The rolling and pitching will be reduced very considerably. The vessel will not make lee-way as formerly; the vibration, or tremulous motion, will be lessened. The safety of the vessel will be very much increased, because the duplex rudder will have the effect of instantaneously changing the direction should she be running into some unexpected danger; also, if one rudder should be damaged, the other can be used to steer with. The propellers also can be used separately when required. For river navigation, the advantages obtained by the two rudders and two propellers will jointly enable the screw principle to be applied to steam-boats plying in shallow water, such as the Thames above London Bridge, or to vessels having small draught of water. For Transatlantic ships the use of the two rudders and two propellers will jointly ensure their making a passage in less time and at less expense than before, also with more certainty and safety than can possibly be done by a single screw or paddle-wheels.
The duplex rudder is applicable to paddle-wheel as well as screw steam-boats.