Search Result for "rider plate":
Wordnet 3.0

NOUN (1)

1. a horizontal beam (or plate) connected to the top of a ship's vertical keel or to the keelson; 



WordNet (r) 3.0 (2006):

rider plate
    n 1: a horizontal beam (or plate) connected to the top of a
         ship's vertical keel or to the keelson