#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
  subtype:  bilge_keel  either of two lengthwise fins attached along the outside of a ship's bilge; reduces rolling
  part of:  hull
  part:  fin_keel__finkeel  a metal plate projecting from the keel of a shallow vessel to give it greater lateral stability

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