thwart
/θwɔːt/
A seat across a boat on which a rower may sit.
The fisherman sat on the aft thwart to row.
A brace, perpendicular to the keel, that helps maintain the beam of a marine vessel against external water pressure and that may serve to support the rail.
A well-made dugout canoe rarely needs a thwart.
An act of thwarting; something which thwarts; a hindrance, an obstacle.