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HISTORY OF MARINE ARCHITECTURE.

or in a narrow channel where there is little room, a vessel may venture to standmuch nearer to the shore than she otherwise would do, being certain of notmissing stays. The measures recommended to be taken in putting about, are,to haul up the sternmost, and immediately to let the fore keel com-pletely down, putting the helm a-lee at the same instant, the ship will comeround almost incredibly fast; so that instead of that sloth, if the term be allow-able, with which the yards of a vessel going about, may frequently appear to beworked in the eyes of those who are unacquainted with the art of navigation,it requires no inconsiderable share of alertness in the people to trim the sailssufficiently quick, particularly in a fresh of wind. The fore keel being hauledup as soon as the ship’s head is brought to the wind, it is ready to prevent, as isgenerally the case with square-rigged vessels, any falling off, which occasionsthe loss of an infinite deal of time: the instant therefore that the sails are full,the fore keel being lowered down, will not only prevent any inconvenience ofthe kind just mentioned, but will cause the vessel, soon as it gets any headway,to fly to, with as much alacrity as if going about; insomuch that some care mustbe taken to prevent the vessel from coming round, by trivially raising thefore keel, as soon as the head is brought in a position to lay the proper course.

The use of the sliding keel is equally advantageous in wearing as in tacking.The measures recommended to be taken are, reversing those of the former operation,to haul up the fore keel, and lower down the sternmost; or, if it is required thatthe vessel should wear round quick, it will be necessary to haul up the mainkeel also, and the ship will turn almost as though it were on a pivot, the rudderbeing at the same time made use of in the customary way. The reason of theeffect produced by the operation just described, will become immediately ob-vious, on the slightest consideration of the acting principle. The fore as wellas main keels bang hauled up, and the stern keel down, the latter acts insome degree as the rudder itself, and has a tendency to prevent the vessel fromfore-reaching. The effect of the after keel, during this operation, is similarto that which would be produced by a rope made fast to the stern in the tideway :the moment the hawser or cable, which had previously kept the head of thevessel to the current, is cast off, the stern would naturally swing round, and takethe same position. Or, to proceed with stating parallel cases, if a vessel draw-ing more water abaft than forward, should chance to take the ground, and her'bows, or fore-body, be afloat, the head will immediately swing round, as itwere, to oppose the current or tide.

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