KEEL, the keel of a vessel. This is a long piece of wood or the assemblage of several pieces put end to end and joined well together, forming the lowest part of the vessel from the stern to the prow in order to support the entire body of the ship, and to determine the length of the bottom of the hold. See Plate I, figures 1 and 2, the keel marked a, and Plate I, figures 1 and 2, the keel noted i .

Since the keels of small ships are not long, they are of a single piece; some are in two pieces; the longest are in three pieces, there are even some with four pieces.

If we compare the body of a vessel to a skeleton, the futtocks are the ribs, and the keel the spinal column; it is the first piece laid in the dock-yard; and to get an idea of it, one or several thick beams must be imagined laid end-to-end, which are assembled together through scarfing or grooves, which, being made in two pieces, form a joining midway, which is held in place by great iron bolts driven from beneath the keel , and pinned or riveted above on ferules; the scarf joints are ordinarily five times as long as the thickness of the keel .

Most builders make the keel curve in the middle and lift up at the ends, or, in technical terms, they give it shearing.

Since the virure or lowest row of planks must be caulked with the keel , a rabbet or channel is cut into it in order to receive these planks.

Here are the rules for dimensions that are adopted by various builders.

The height or vertical face of the keel is one eighth its length expressed in inches, or, what amounts to the same thing, the perpendicular height of the keel above the blocks or stocks that carry it, is one line six points for each foot of its length; which has the same height along its entire length. [1]

The horizontal width of the keel in the middle is ten lines eight points per inch of its height; it declines by one fifth toward its extremities.

The keel is given more height than width, because the scarfings are taken in this direction, and because given the same amount of material it is stronger that way.

The depth of the channel of the keel is determined by the thickness of the lowest plank, which is called the garboard-streak . [2]

Ships end in the front with a piece of wood that has a circular form: this is what is called the rake of the stem ; and behind by a piece of wood that falls obliquely upon the keel, projecting outward; it is this projection that is called the rake of the sternpost.

To calculate the length of the keel, it is necessary to add the sum of the rake of the sternpost and the rake of the stem, then subtract the result of these two sums from the length of the keel . It is thus necessary to begin by determining the rake of the sternpost and the rake of the stem.

To find the rake of the stem, several builders used to take one eighth of the total length of the vessel, and they gave as the rake of the sternpost, a quarter of the rake of the stem; thus a vessel of 168 feet in length would have had 21 feet of rake of the stem, and five feet three inches of rake of the sternpost.

Other builders give for the rake of the stem the twelfth part of the total length of the vessel, for vessels of 60 cannons and above: for those of from 40 to 60, the fourteenth part of the length, and the fifteenth for the small ones. There are also builders who take only the fifteenth part of the total length, even for the great vessels; and for the rake of the sternpost, the sixth part of the rake of the stem. (By great vessels is understood those of 40 cannons and above.) Thus taking the fifteenth part, a vessel which would have 168 feet of length, would have 11 and one quarter feet of rake of the stem, and one foot 10 and one-half inches of rake of the sternpost. For frigates, they take the thirteenth part of the length of the vessel for the rake of the stem, and the sixth part of this length for the rake of the sternpost.

For small frigates of 22 cannons and below, they take the fourteenth part of the total length of the vessel for the rake of the stem, and the sixth part of the length for the rake of the sternpost; finally, some builders, to have the rake of the sternpost and the rake of the stem, take 1/10 or 1/12 of the total length, divide this quantity into five equal parts; they assign four of them for the rake of the stem, and one for the rake of the sternpost.

With respect to the thickness of the keel, there is a rule adopted by several builders, which is to take as many inches as 1/3 and 1/8 of the midship beam have feet.

Example. A vessel of 70 cannons has 42 feet of midship beam, one-third of 42 is 14, one-eighth of 41 is 5 feet 3 inches; adding these two sums together, we have 19 feet 3 inches: thus the thickness at one inch per foot is 1 foot seven inches 3 lines.

1. An inch was traditionally divided into 12 lines, and each line into 12 points; so one point was 1/144th of an inch.

2. In translating this term and others in this article recourse has been had to the corrected edition of William Falconer’s Universal Dictionary of the Marine : or, A Copious Explanation of the Technical Terms and Phrases Employed in the Construction, Equipment, Furniture, Machinery, Movements, and Military Operations of a Ship. Illustrated with a Variety of Original Designs of Shipping, in Different Situations; Together With Separate Views of Their Masts, Sails, Yards, and Rigging. To Which Is Annexed, a Translation of the French Sea-Terms and Phrases, Collected from the Works of Mess. Duhamel, Aubin, Saverien, etc. (London: T. Cadell, 1780).