Nautical beam is a term used in sailing and refers to the width of a boat. The two main components of a nautical beam are the MAST and the KEEL. The MAST is a vertical pole that supports the sails and rigging, while the KEEL is a long, flat structure that runs along the bottom of the boat and provides stability. Together, these two components form the nautical beam, which is an important factor in determining the size and maneuverability of a boat.