#keel  one of the main longitudinal beams (or plates) of the hull of a vessel; can extend vertically into the water to provide lateral stability
  supertype:  beam  long thick piece of wood or metal or concrete, etc., used in construction
  part:  fin_keel
  part of:  hull
  subtype:  bilge_keel__bilgekeel  either of two lengthwise fins attached along the outside of a ship's bilge; reduces rolling

No statement uses or specializes keel; click here to add one.