Navigation, a piece of timber turning on hinges in the stern of the ship, and which, opposing sometimes one side in the water and sometimes another, turns or directs the vessel this way or that. See Helm.

In the seventh volume of the Transactions of the Society instituted at London for the Encouragement of Arts, Manufactures, and Commerce, there is explained a method of supplying the loss of a ship's rudder at sea. The invention, which is Capt. Pakenham's of the royal navy, has been approved by Admiral Cornwallis, the commissioners of the admiralty, by the society in whose transactions the account of it was first published, and who presented to Capt. Pakenham their gold medal, by the Trinity-house, by the managing owners of East India shipping, by the duke of Sutherland then regent of Sweden, and by the society for the improvement of naval architecture. The substitute here recommended for a lost rudder, says the inventor, is formed of those materials without which no ship goes to sea, and its construction is simple and speedy. Capt. Pakenham, however, did not give a particular account of his invention to the society whom he addressed, and to whom he sent a model of his invention, till such time as he had an opportunity of reducing the theory he had conceived to practice. On the 7th of July 1788, he made this trial with the Merlin of Newfoundland; and he declares that, during the different manoeuvres of tacking and wearing, he could not discover the least variation between the operation of the machine and that of the ship's rudder: she was steered with the same ease by one man, and answered the helm in every situation fully as quick. Admiral Cornwallis certifies the same with respect to the Crown of 64 guns, which lost her rudder on the Kentish Knock, when with the substitute she was steered to Portsmouth with the utmost ease in a heavy gale, and, as the admiral affirms, it would have taken her to the East Indies.

The materials and construction are thus described in ccclxxvi. of the Transactions. "No 1. A topmast inverted; the fid-hole to ship the tiller in, and secured with hoops from the anchor-blocks; the heel forming the head of the rudder. No 2. The inner half of a jibboom. No 3. The outer half of a jibboom. No 4. A fish: the whole of these materials well bolted together—in a merchantman her ruff-tree. No 5. A cap, with the square part cut out to fit the stern-post, and acting as a lower gudgeon, secured to the stern-post with hawser, leading from the bolts of the cap, under the ship's bottom, into the hawse-holes, and have well tort. No 6. A plank, or, if none on board, the ship's gangboards. No 7. Anchor-blocks, made to fit the topmast as partners, secured to the deck, and supplying the place of the upper gudgeon, and in a merchant ship the clamps of her windlass. No 8. A stern-post. No 9. Hoops from the anchor-blocks. No 10. Pigs of ballast, to sink the lower part. The head of the rudder to pass through as many decks as you wish."

On this the Captain makes the following remarks: "It might probably be supposed, that a difficulty would occur in bringing the jaws of the cap to embrace the stern-post; but this will at once be obviated, when it is remembered that the top-chains, or hawser, leading from each end of the jaws, under the ship's bottom, are in fact a continuance of the jaws themselves. Nor can it be apprehended that the cap, when fixed, may be impelled from its station, either by the efforts of the sea, or the course of the ship through the water, though even the hawser, which confine it in the first instance, should be relaxed:—the experiment proves, that the partners must be first torn away, or the main-piece broken off.

"Since the improved state of navigation, notwithstanding remedies have been found in general for the most disastrous accidents at sea, experience has convinced that nothing complete had been hitherto invented to supply the loss of a rudder. The first expedient within my knowledge were cables veered aftward, with tackles leading from them to the ship's quarters. This practice was superseded by the invention of the machine usually called the Ipswich machine; but the construction of it is complex and unwieldy, and vessels are seldom found in possession of the materials which forms it. Commodore Byron, in the Journal of his Voyage round the World, says, that the Tamer, with every assistance from his own ship, was five days in constructing it. Besides, like the before-mentioned scheme, it can only operate to steer a ship..." ship large (and that but very wildly), and of course, under the circumstance of a lee-shore, defeat the most skilful exertions of a seaman. Several other expedients have been adopted, which I shall not mention here, as the same defects equally appear in all.

Thus it was apparent, that ample room was left for the discovery of some more certain resource than any of the former; and the scheme which has suggested itself to me, will, I trust, be found fully to answer the purpose intended. The materials are such as fearlessly any ship can venture to sea without; and the construction so speedy, easy, and simple, that the capacity of the meanest sailer will at once conceive it. I need not, from mathematical principles, show the certainty of its effect, as it is formed and managed in the same manner as a ship's common rudder: and as the common rudder is certainly of all inventions the best calculated for guiding a vessel through the water, it will of course follow, that whatever substitute the nearest resembles that, must be best adapted to supply its loss."