A weight attached to or incorporated into the keel of a vessel to serve as ballast; especially a heavy metal moulding attached to the keel of a sailing vessel.
Origin
Early 19th century.
Definition of ballast keel in US English:
ballast keel
noun
A weight attached to or incorporated into the keel of a vessel to serve as ballast; especially a heavy metal moulding attached to the keel of a sailing vessel.