Deadwood

Deadwood:
Heavy longitudinal timbers fastened over the keelson. The timbers of the bow and stern are fastened to the deadwood.
Deck:
A permanent covering over a compartment, hull or any part of a ship serving as a floor.

DEADWOOD The reinforcing structure built in between the keel and keelson in the after body of a ship or back of the joint between the stem and the keel in the fore body. DECK A deck in a ship corresponds to a floor in a building.

Deadwood: A wooden part of the centerline structure of a boat, usually between the sternpost and amidships.
Decks: The top of the boat; the surface is removed to accommodate the seating area.

The fin proper gives lateral resistance in an almost perfect form, for there is no deadwood either forward or aft and the least possible amount of wetted surface.

Smith took out his patent for the propulsion of ships by means of a screw fitted in a recess formed in the deadwood, in May 1836, and in July of the same year Ericsson, then practising as a civil engineer in London, took out his patent.

If you cut the keel off along the vertical line of the aft deadwood and hung a spade rudder aft it would be a low aspect ratio fin keeler. Chuck just attaches the heel fitting for the big rudder to an extended section of the keel.

In yachts built with iron knee floors it is a common practice to fill up all cavities along the keel or hogging piece, fore deadwood and apron, and deadwood aft, with cement, after coating the wood with.