IT is very difficult to ascertain with any degree of exactitude when sliding or drop-keels first came into use. In the third volume of " An History of Marine Architecture," by John Charnock, F.S.A., published in 1802, there is a chapter (No. XIII., p. 337) devoted chiefly to the description and use of sliding-keels as claimed to have been invented by Captain Schank.* It is not however quite clear whether Captain Schank was the inventor or only the adapter, for a plate is given, Fig. 1, which represents a boat built at Boston in New England in the year 1771 for Earl Percy, who subsequently became Duke of Northumberland; whereas Fig. 2 shows a boat fitted at Deptford with three sliding-keels in 1789 in accordance with Captain Schank's ideas, and his celebrated Trial Cutter, which was built by order of the Government, does not appear to have been launched until 1790, as the reports of her trials are dated 1791-2.

Drop-keels have come into such general use in the Life-boat service since their first introduction in 1884, when, it will be remembered, the Clacton Lifeboat was fitted with one, that doubtless some slight account of their early history may be acceptable to those readers of ' His name is sometimes spelt Schanck.

the LIFE-BOAT JOURNAL who may not have had an opportunity of seeing Charnock's book.

It is very unfortunate that so little reference is made to the boat shown in Fig. 1, which " represents a boat built at Boston in New England in the year 1771 for Earl Percy, now Duke of Northumberland. It was furnished with a continuous and uninterrupted slidingkeel by means of which it could be worked without a rudder." Such is the meagre description which leaves us longing for further information. As to the name of the inventor, or whether there were other boats of the same description built previously or at the same time as that built for Earl Percy, Charnock is silent. It is curious to note that the first drop-keels used in the Life-boat service were of the same shape as that shown in Fig. 1. Several Life-boats were fitted with drop-keels of this form, arranged so as to be lowered at each end, a contrivance which did not prove very satisfactory, and which led to the present forms, in which the drop-keels are lowered at the after-end only.

The chapter in Charnock's book alluded to above gives a long account of the reasons which led to Captain Schank's invention, from which it is necessary to quote. " Captain Schank states very properly that, in the case of a frigate drawing seventeen feet of water and another frigate of the same burthen drawing only eleven feet (fitted with sliding-keels), the last will have a body of six feet less fluid to divide, a body of water to displace and force herself through equal to the difference between eleven and seventeen; when it is considered, in addition to this, that the resistance of the fluid increases in proportion to the depth it is acted opposing only one, two, or three keels as may be found necessary to make her hold a good wind, while the first has six feet perpendicular depth of her hull depressed, being about one-third of her real size. It follows therefore she has against, the disparity is almost incredibly increased. North-country built vessels, or those in the coal trade, are a strong proof of this observation. These in general draw one-third less water than any other of British construction; yet Fig J.

when employed as transports they are generally found to sail as fast as any other, and when going before the wind in ballast or half-loaded frequently beat the ships belonging to the Royal Navy.

When however they are close hauled in a wind they will drop to leeward; but were they furnished with slidingkeels there is no doubt but that they would have the advantage over all other English vessels. The Dutch, who bestow little pains in making their trading vessels sail, are nevertheless not totally unfortunate in this respect; for when they are light they sail fast before the wind, owing to their small draft of water. They have also other vessels, built almost totally flat, such as pilotboats, yagers for carrying the first herrings to market from Shetland, and pleasure yachts. All these have leeboards, by the assistance of which they sail as fast as the generality of those which navigate the Northern seas; circumstances which are manifestly in favour of flat-floored vessels and slidingkeels." Then follows a long disquisition on the relative merits of vessels built sharp forward and aft, and vessels with long flat floors provided with sliding-keels, from which a few extracts are of special interest. " Experience and the occurrences of many years prove that the North-country built ships, all of which have flat floors, and the Dutch fishing-boats will ride at anchor when the violence of the wind and sea would render it extremely dangerous and perhaps impossible for those of any other construction to persevere in the same measure." " Captain Cook, whose practical knowledge in navigation and the properties of a vessel stood, perhaps, inferior to that of no person in the world, gives a decided preference in favour of the flat-floored vessel as being best calculated for a distant and perilous voyage." The obvious advantage that flat-floored vessels have over deep vessels on such occasions when they take the ground, either by accident or for convenience, is another point strongly dwelt on; and as in those days it was a frequent practice to run vessels aground, both in. harbours and on open, beaches, for the purpose of discharging cargo, Captain Schank adduces this as another strong reason for -flat-floored vessels and sliding-keels. Captain Schank was a strong advocate for building ships in watertight compartments, in which he appears to have been a long way ahead of his times ; a good deal of the chapter on sliding-keels is occupied by this question of "bulkheads rendered watertight," an interesting subject, but not necessary for the purposes of this article.

Fig. 2, as previously stated, represents a boat built in 1789 at Deptford, and fitted with three sliding-keels, under the direction of Captain Schank. The arrangement of the sliding-keels is precisely similar to that adopted in the Trial Gutter, built in the following year.

It will be seen that the keels are of a spade-like shape and of considerable depth, and when housed or triced up the upper edge comes up as high as the gunwale.

Sliding-keels of a very similar shape are still in use, notably at Wexford, in the flat-bottomed punts which ply between the town and Rosslare Point.

Fig. 3 is a transverse section of the Trial Cutter with her sliding-keel lowered down, also showing the winch and rope used for lowering and hoisting the keel; each keel had two winches and ropes, the one made fast to the after and the other to the fore side of the sliding-keel.

Like most inventors, Captain Schank was very confident of his invention, and claimed advantages for it which were perhaps rather too far-reaching. After describing how unlikely a vessel fitted with sliding-keels is to be thrown on her beam-ends or broach to, he says: "The use of sliding-keels is known by actual experience to counteract all mischances and disasters of this kind. In fresh breezes, or in light winds, it is totally immaterial how much sail is set or how it is disposed, since the act of raising or lowering the keels will immediately counteract the inconvenience that might otherwise arise from carrying too much sail, either forward or aft. . . .

In a gale of -wind it is necessary that the main and fore-keels should be hauled close up and the stern-keel let down to such depth as shall be found necessary to make the vessel steer perfectly easy." Captain Schank then proceeds to explain the method of using the keels in tacking and wearing, which is best described in his own words : "Vessels furnished with two or three sliding-keels will tack with far greater readiness than those which are destitute of them, inasmuch as the fore and sternmost keels have each of them an effect on the vessel little inferior to that of the rudder itself. In working to windward, or in a narrow channel where there is little room, a vessel may venture to stand nearer to the shore than she otherwise would do, being certain of not missing stays. The measures to be taken in putting about are to haul up the sternmost and immediately let the fore-keel completely down, putting the helm a-lee at the same instant, the ship will come round almost incredibly fast. . . . 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 that the 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 rudder being at the same time made use of in the customary way. The reason of the effect produced by the operation just described will become immediately obvious on the slightest consideration of the acting principle. The fore as well as the main-keels being hauled up and the stern-keel down, uhe latter acts in some degree as the rudder itself, and has a tendency to prevent the vessel from fore-reaching. The effect of the after-keel during this operation is similar to that which would be produced by a rope made fast to the stern in a tideway; the moment the hawser or cable which had previously kept the head of the vessel to the current is cast off, the stern -would naturally swing round, and take the same position. Or, to proceed with stating parallel cases, if a vessel drawing more water abaft than forward should chance to take the ground and her bow or forebody be afloat, the head will immediately swing round, as it were, to oppose the current or tide." The Trial Cutter proved very successful, as is shown in the reports of her officers, dated 21st February, 1791, and April, 1792, and the categorical answers to a Yisb oi (ja.eatV.ona as. to lass Vvuvdvness and seaworthiness were extremely favourable. Sailing trials were carried out against five cutters, three squarerigged ships, and a brig, all of which she beat, and in answer to a question the lieutenant in command (Lieutenant Micajah Malbon) stated : " I never was with any King's cutter that beat her." In April, 1792, she was taken into dock at Woolwich and carefully inspected by the Dockyard Staff, who found no defect in her, but stated they were of opinion vessels so constructed would be a little more expensive than others.

In spite of the excellent reports on the Trial Cutter, sliding-keels do not appear to have come much into vogue until about the middle of the nineteenth century. Very likely Captain Schaak, in his zeal, rather wished to prove too much. In any case his theories were correct and the sliding or drop-keel, used in its proper place, has proved a most valuable invention and one of its proper places is in Life-boats, which ia the nature of their work must be of shallow draught and have long flat floors..