Remarks on the Construction of Vessels

By Col. Beaufoy, FRS.

(To the Editors of the Annals of Philosophy.)

Bushey Heath, Stanmore, Sept. 13, 1824.

DEAR SIRS, The readers of the Annals of Philosophy will be gratified to learn, that the Admiralty, in addition to the improvements already introduced into the navy, have given orders for building three vessels (the Orestes, Champion, and Pylades) upon different principles, suggested, I believe, by Prof. Inman, Capt, Hayes, R.N. and Sir Robert Seppings. As these ships have nearly equal length, breadth, and tonnage [1] and as great theoretical knowledge and ability will be exercised in giving to every vessel that form which each individual considers the most advancement of naval architecture may be expected from the above collision of intellect.

When these ships proceed to sea for the purpose of comparing their respective qualities, it is possible considerable difference will be found in their sailing. This inequality may proceed from dissimilarity in the length of the masts and yards, and consequently in the size of the sails. The bow of one may be better adapted than the others for dividing the water, or the after part may possess a more efficacious shape. The stowing of the ballast, the smoothness of the bottoms, or superiority of seamanship, will also severally produce a disagreement in their rates of sailing. The latter can, however, be detected, by chainging the officers from ship to ship. An alternation in the distribution of the ballast will produce a correspondent fluctuation in the merits of each vessel; the best sailor becoming worse, and the dull better; but with respect to the fore and after bodies, how far the particular form of each contributes to the fast sailing, it will be impossible to judge from want of sufficient knowledge of the resistance of non-eleastic fluids. This branch of mechanical science being very imperfectly understood, it cannot be expected that the shape of vessels can be advantageously altered, until the improvement is founded on the solid basis of experiment. Then, and not before, constructors will be able to give satisfactory reasosns for adopting one form in preference to another.

To place in a conspicuous point of view the various opinions which writer on naval subjects entertain respecting the resistance of water, I will commence with the remarks of Monsieur Romme, Correspondent de l'Acad‚mie des Sciences de Paris, et Professeur-Royal de Navigation des Eleves de la Marine. This gentleman, in the year 1787, published a quarto book on naval affairs; and therein states, that the resistance a vessel meets when sailing is almost independent of the form of the bow; the impulse of the water being the same, provided the greatest vertical section remains unaltered. And this theory is represented as, confirmed by experiment, made with two models of a seventy-four gun ship; one model had the bow formed in the usual manner with curved lines; the other had a similar midship bend, but the bow consisted of strait lines; yet notwithstanding this great dissimilarity of shape, both were equally resisted when moving with equal celerity. M. Romme could not discover that these models experienced more or less resistance effected when the vessels were cut in two, and the head of one joined to the tail of the other.

Mr. Stalkartt, in his Treatise on Ship Building, recommends the segment of a circle as best adapted for dividing the water; and others prefer the parabola. Such contrariety of opinions only prove, how little we know on the subject; and the importance of estanblishing some more correct rule for drawing the water-lines of vessels, than the mere fancy of the draughtsman.

The tonnage of the Royal navy in round numbers may be estimated at 450,000; the expense of building, taking one vessel with another at 20 l. per ton; the value of all at nine millions. To the expense of the hulls must be added the cost of the masts, yards, sails, cordage, and many other et ceteras, requisite for the equipment; this doubles the amount, making 18,000,000 for the primary sum laid out on men of war. The durability of the ships in time of peace may be now calculated at 14 years; during war at 10 years; the average is 12 years; consequently 1,500,00 l. of money is annually expended in keeping these bulwarks of the nation in an efficient state.

Every one will assent that the construction of such costly machines should, in the first instance, be as perfect as possible; hence arises the question, how, and at waht expense, is so desirable an end to be accomplished? The increase of 1/18000th part on the annual expenditure, would secure this point; for the application of the comparatively small sum of 100 l. in making a complete set of experiments, in all probability, would be attended with most beneficial results for the future constructure of ships.

Let it be borne in mind the sums of money which are year after year laid out to encourage a superiority of far less moment to the United Kingdom than the excellence of the navy: there are plates, sweepstakes, and purses, for breeding fleet horses; in a national point of view, it is of little consequence whether the average rate of a racer be 37 or 38 miles in the hour; but widely different is the case, if the sailing of our men of war be increased one knot, or half a knot, in the same space of time. By such improvement an enemy's fleet may be taken, or an island captured, or a colony preserved; and who would not rather read in the Gaszette a dispatch from an Admiral, stating that in consequence of the superior sailing of his fleet he had come up with, and captured the enemy, than peruse in the public papers that at Newmarket, or an other celebrated racing ground, after a well contested run, one horse was declared the winner by half a neck, and the prize adjudged accordingly.

If the union of capacity with quickness of sailing be deemed impracticable, the error of such opinion is fully demonstrated by reference to the engravings accompanying a work on the Elements and Practice of Naval Architecture, by Mr. David Steel; who there gives the draught of a London trader particularly distinguished for capacity and velocity; -- a circumstance the more remarkable in a merchantman, as the variety of the cargoes would be tantamount to alteration of stowage; and consequently if the same vessel, under such circumstances, continues to remain a prime sailor, it is evident this superiority depends on the curves that divide the water.

Discoveries are continually making in chemestry, magnetism, and galvanism; improvements are introduced in chronometers, and mathematical instruments; all these advantages proceed either from experiment or observation, and it only requires the powerful influence of my Lord Melville, to expel, by simlar means, the mist that at present envelopes the science of hydrodynamics; and to place this negelected branch of knowledge in the elevated situation it so justly merits from its importance to a maritime nation.

I remain,

Dear Sirs, yours very truly,

Mark Beaufoy.

                        Orestes.        Champion.         Pylades.
                        Feet In.         Feet In.         Feet  In.
Length on deck . . . . . 109 11 . . . . . 109  6 . . . . . 110   1
Breadth extreme  . . . .  20  6 . . . . .  30  6 1/2 . . .  30 1/4
Depth in Hold  . . . . .   7  6 . . . . .   7  8 1/4 . . .   8   3
Builder's tonnage  . . . 460  0 . . . . . 456  0 . . . . . 433   0
Light draft of water   Afore.
                           8  6 . . . . .  10  8 . . . . .   8   8 1/2
                          11  0 . . . . .  10 10 . . . . .  10  11
Transcribed by Lars Bruzelius

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