The first part of a ship “laid down” is the “keel;” this is the
projection which runs along the whole length and forms the lowest
part of the ship. The ship is built in what is called the “building
slip,” which slopes towards the water; in this “slip” a row of oaken
blocks are placed at a few feet apart, and about three feet high, on
which the keel is laid; these blocks are for the purpose of allowing
the workmen to cross from side to side below the keel and to form a
foundation for the ship to rest on. In fig. 1, A is this arrangement
of blocks, C the keel, at the hinder part of which is the “dead
wood,” or the timbers filling up the space between the keel and the
curved bottom of the ship, which is more curved than the keel, and
very much so towards the “stern” or hindermost part. Across the keel
are laid the “floor-timbers” or “ribs,” B, which are curved timbers
laid at right angles to the keel and passing outwards and upwards
in the exact curve which the sides of the ship are to assume; these
are too curved and too long to be of one piece, others, therefore,
are added, and joined end to end with the first by wooden bolts or
“dowels;” these curved timbers are cut to a pattern, chalked on the
floor of the “mould-loft.” The ribs as they cross the keel are bound
to it by a piece of strong timber running along inside of or above
them, but parallel to, and exactly over it, which is called the
“keelson,” and is bolted to the keel through the centre of each lower
piece of the ribs or floor-timbers; it is shown at D, fig. 1. In
large ships there are three of these keelsons, running side by side,
and forming a strong support to the masts, which rest upon them.
At each end of the keel a bar of timber rises, the hindermost being
called the “stern-post,” and that in front the “stem-post” (marked E
and F in fig. 1). Across the ribs on the outside and parallel to the
keel, are laid the “planks,” which are boards of oak of from two to
six inches thick, laid close together and touching at their edges;
these are fastened to the ribs by plugs of oak, called “treenails,”
going right through the planks and ribs, and wedged at each end (fig.
2). In large ships, similar planks line the inner side of the ribs,
and oblique or diagonal braces are also sometimes used, to strengthen
the ship and keep it from curving or “arching” when in the water.