sentences:  Modern ships are now largely built in a series of pre-fabricated, complete hull sections rather than being built around a single keel.The event recognized as the keel laying is the first joining of modular components, or the lowering of the first module into place in the building dock.It is now often called "keel authentication", and is the ceremonial beginning of the ship's life, although some modules may have been started months before that stage of construction.