a piece of timber which may be properly defined the interior or counter part of the keel; as it is laid upon the middle of the floor timbers, immediately over the keel, and like it composed of several pieces scarfed together. In order to fit with more security upon the floor timbers and crotches, it is notched about an inch and a half deep, opposite to each of those pieces, and thereby firmly secured down upon them to that depth, where it is secured by spike-nails. The pieces of which it is formed are only half the breadth and thickness of those of the keel.

The keelson serves to bind and unite the floor-timbers to the keel. It is confined to the keel by long bolts, which, being driven from without through several of the timbers, are forelocked or clenched upon rings on the upper side of the keelson.