PLAN ET CONSTRUCTION DU YACHT COLUMBIA

Catégorie : COLUMBIA

© 1899 SCIENTIFIC AMERICAN, INC : JUNE 24, 1899

Designer Herreshoff has never been known to take a retrograde step. Each yacht that he has turned out in any class has been faster than its predecessors, and we have every confidence, therefore, that Columbia will be superior to Defender.

In an article published in the Proceedings of the United States Naval Institute, in 1897, on the subject of the yacht Defender, Naval Constructor Hobson (now of “Merrimac“ fame) says :

The idea that gives the distinguishing feature to this advanced type is the realization of extreme sail-carrying power from a great metacentric height—initial and under inclination—realized from the disposition of weights. The great metacentric height, and consequent sail-carrying power, is derived more from the element of weight than from the elements of form.

The method adopted in realizing the low position of the center of gravity is that of reduction in weight of hull and fittings, and the addition of weight to the keel the weight being taken from the upper portions and added to the lowest point. The method of realizing a reduction of high weights is the use of light materials and light scantlings, with a light method of construction and fastenings. The reduction of frictional resistance and the liability to deterioration are sought in the use of manganese bronze for water-washed portions.

Comparing Columbia with Defender, the question arises as to where she exhibits a gain in construction and form over the earlier boat. In general, it may be said that, while she derives equal sail carrying power from the element of weight due to her light construction — in which respect, in spite of the absence of aluminum, she is probably at least equal to the “ Defender “—she derives more power from the element of form than did the Defender. She has a gain in distribution of weight, due to the fact that her lead is carried lower down, that the keel is straight and level on the bottom for its full length, and that the greatest thickness of the lead is within a few inches of its bottom, and not, as in the Defender, two or three feet from its lowest point. This is evident from a comparison of the midship section of the Columbia as given above, with that of the Defender.

From the same section it will be seen that the changes in form in the new boat will give her considerably more stiffness and power. The bilge is considerably harder, that is to say, it rounds with a shorter radius, the floor is flatter, with less dead rise, and the curve where the floor rounds into the keel has a smaller radius than in the Defender. The effect of these changes is that the center of displacement of the hull proper is raised, while at the same time, as we have just seen, the center of gravity of the lead is lower. These changes, coupled with an increase of over a foot in the beam, will evidently enable the new boat to carry a. heavier press of canvas than the Defender.

At the same time, although her beam is greater, the lines of the Columbia, because of her greater length, are finer than those of the older boat. She is from a foot to a foot and a half longer on the waterline and between 5 and 8 feet longer on deck. Her overhang, both forward and aft, is truly enormous, being about 18 feet forward and 22 feet aft as against 15 feet forward and 17% feet aft in the Defender. The lines are carried out in a gradual sweep that will give the boat long and easy sailing lines when she lies down under a press of canvas. The topsides amidship have a slight "tumble home" or inward inclination, but this only extends for a short distance amidship, and. as will be seen from the sections at frames 12 and 60, the sides flare out liberally on the counter and toward the bow.

It will be evident from the drawings and our description that the Columbia is more completely of the fin-keel type than was the Defender. The fin is narrower, the lead lower, and the body of the boat is wider and not so deep.

As regards the constructional details, the drawings which we herewith publish speak for themselves. The deck beams are of bulb angle steel rolled to a special section, above which there is a system of diagonal intersecting steel straps, forming a horizontal trussing to distribute the lateral strains of mast and stays and resist the torsional and racking strains to which the hull is subject when in a seaway or heeling to a strong breeze. Above the horizontal strapping is a two-inch deck of wood. The wood deck does not extend to the outside rail, but finishes on either side at steel deck-stringers, which form, as it were, the chords of the deck trussing. The stringer is 20 inches wide amidships, and tapers to 10 inches at the bow and stern. Along its inner edge is a 1¾X1¾ inch steel angle, and on the outer edge is riveted a steel bulb angle, 1¾X3¼ inches, the bulb flange forming the rail of the boat. About 6 feet below the deck is a very light platform deck forming the cabin floor, and a series of 2-inch tubular steel struts extends diagonally from the deck beams to the side of the vessel just above the platform deck, the struts being fastened at each end to longitudinal bulb angles which extend fore and aft beneath the deck beams and across the frames at the points indicated in the drawings. About the neighborhood of the garboard strakes, where the floor rounds into the keel, the vessel is strengthened by a series of steel plates, as shown, which extend from frame to frame throughout that part of the body of the boat which lies immediately above the lead keel. Another of our drawings shows the method of stepping the mast, which is placed at frame 28. The mast-ring is a bulb angle steel, 2½X 4 inches, and measures 26 inches in diameter, the mast being 21 ¼ inches in diameter at the level of the deck. The mast step, which is 6 feet below the deck, consists of a half-inch steel plate which is slightly dished downward, and carries above it a steel ring forged from a 3 X 3 angle. Below the plate is another ring, 2 X 2 inches, the two rings and the plate being firmly riveted together. The step is carried by a strong box-like structure of steel plating, the bottom of which is riveted to the hull plating and to the frames. The fore an d aft strains are distributed over a considerable section of the hull by means of steel keelson plates which extend forward between frames 27 and 25, and aft between frames 29 and :12. All of this work is flanged and carefully riveted and forms an extremely light, strong, and well-designed construction. The distance from the deck to the step plate is 6 feet 4½ inches and from the plate to the stem of the vessel about 5 feet. The depth of the Columbia at this point is therefore about 11 feet. The deck and hull in the wake of the mast are also stiffened by six 1⅛¾-inoh round steel stanchions, three on each side, which extend diagonally from the mast step to the deck stringers which form the scuppers or waterway of the yacht.

Others of our drawings show the construction of the rudder and the novel methods which have been devised for carrying the same, together with the new form of steering gear, which was designed especially for the Columbia. The rudder post is about 27 feet in length over all. It enters the hull between frames 59 and 80. Here it is provided with a stuffing-box to prevent the entrance of water. The rudder consists of bronze plates riveted upon a frame, as shown in the enlarged drawing, and it is 4 inches thick at the post and tapers to between 1 and 2 inches in thickness on the outer edge. To the top of the rudder post is attached a. steering quadrant, of the form shown in the small drawing of the same. It extends to the rear and downwardly and engages a bevel wheel carried at the bottom of a. vertical shaft which rises through the deck, and carries at its upper end another bevel wheel, which is itself in engagement with a bevel wheel on the shaft of the steering wheel. lmmediately below the quadrant the rudder-post passes through a heavy casting which is bolted to a plate steel foundation and serves as a top bearing for the post and at the same time carries practically the whole weight of the rudder, which is kept in place by the usual pintles and gudgeons. At frames 20 and 60 are watertight bulkheads of light plating.

Will Columbia win? We can only say that she is a logical development and an unquestioned improvement on “Defender,” and "Defender" is a few minutes faster than the fastest boat that has ever come for the “America” cup.