Keel

The main and lower timber of a ship, extending longitudinally from the stem to the stern-post. It is formed of several pieces, which are scarphed together endways, and form the basis of the whole structure. Of course it is usually the first thing laid down upon the block for the construction of the ship.

Keelson, or, more commonly, Kelson. The timber, formed of long square pieces of oak, fixed within the ship exactly over the keel (and which may, therefore, be considered as the counterpart of the latter) for binding and strengthening the lower part of the ship, for which purpose it is fitted to and laid upon, the middle of the floor timbers and bolted through the floors and keel.