THWARTS

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.

To cause to fail; to frustrate, to prevent.

"Our plans for a picnic were thwarted by the thunderstorm."

To place (something) across (another thing); to position crosswise.

To hinder or obstruct by placing (something) in the way of; to block, to impede, to oppose.