Illustration from 1908 Chambers's Twentieth Century Dictionary.
<b>Lee-board</b>, <i>n.</i> a board lowered on the lee-side of a vessel, and acting like a keel or centre-board to prevent her from drifting to leeward.
Rev. Thomas Davidson 1856-1923 (<i>ed.</i>)
Chambers's Twentieth Century Dictionary of the English Language