society > travel > travel by water > vessel, ship, or boat > parts of vessels > body of vessel > [noun] > timbers of hull > frame > additional timbers strengthening (4)
riderc1620
Nautical. In plural. An additional set of timbers or iron plates used to strengthen the frame of a ship internally or externally.
futtock-rider1769
(see quot. 1867).
fortification1820
spec. The strengthening timbers, etc. of a whaling vessel: see fortify, v. 1b.