The Collaborative International Dictionary of English v.0.48:
Garboard \Gar"board\, n. (Naut.) One of the planks next the keel on the outside, which form a garboard strake. [1913 Webster] Garboard strake or Garboard streak, the first range or strake of planks laid on a ship's bottom next the keel. --Totten. [1913 Webster]