RIBBANDS

The ribbands, being judiciously arranged with regard to their heighth and distance from each other, and forming regular sweeps about the ship's body, will compose a kind of frame, whole interior surface will determine the curve of all the intermediate, or filling-timbers, which are stationed between the principal ones. As the figure of the ship's bottom approaches to that of a conoid, and the ribbands having a limited breadth, it is apparent, that they cannot be applied to this convex surface without forming a double curve, which will be partly vertical and partly horizontal; so that the vertical curve will increase by approaching the stem, and still more by drawing near the stren-post. It is also evident, that by deviating from the middle line of the ship's length, as they approach the extreme breadth at the midship-frame, the ribbands will also form an horizontal curve. The lowest of these, which is terminated upon the stem and stern-post, at the heighth of the rising-line of the floor, and answers to the upper part of the floor-timber upon the midship-frame, is called the floor-ribband. That which coincides with the wing-transom, at the height of the lower-deck upon the midship-frame, is termed the breadth-ribband: all the rest, which are placed between these two, are called intermediate ribbands.

From this double curve it results, that the ribbands will appear in different points of view, when delineated upon different planes of the same ship. To conceive this, let us suppose the skeleton of a ship upon the stocks, as in plate IV. fig. II. and plate X. fig. 2. with the ribbands represented by dotted lines upon her bottom. If a spectator is placed opposite to the stem or stern-post, on a line prolonged from the keel, he will only view the projection of the ribbands on the plane of the midshipframe, in which the horizontal curve is very little perceived; he will discover part of the vertical curve, which rises continually from the extreme breadth towards the stem and stern, so that they must be drawn upon the plane of projection as oblique lines, which terminate upon the midshipframe at the point where the ribband touches it, and upon the stem and stern-post at the point where their ends are lodged.

Plates IV and X

If the spectator were to change his position, and perceive the projection of the ribbands upon a plane, supposed to be elevated upon the length of the keel, he would also discover their vertical curve, as it is sometimes expressed in the sheer-draught, without distinguishing the horizontal one.

But if we imagine the eye of the spectator placed considerably above the ship, on a line perpendicular to the middle of the keel, he will then discover the projection of the ribbands upon the plane of the ground beneath the ship, and view the horizontal curve, (see the horizontal plane, plate I ) without perceiving the perpendicular one.

Plate I

In order to give the reader as distinct an idea as postible of the ribbands, we have, besides the above representations, exhibited a perspective view of them in the frame or skeleton of a small vessel, referred to, from the article TIMBER.

Reference Works