Sternpost

A sternpost is the upright structural member or post at the aft end of a ship or a boat,[1][2] to which are attached the transoms and the rearmost part of the stern.

[3] The sternpost may either be completely vertical or may be tilted or "raked" slightly aft.

[4] It rests on or "fays to" the ship's keel.

[1] Traditionally, the rudder was suspended from the sternpost, and the propellers descended from it.

[1][2] With changes in how these are positioned, in modern shipbuilding vessels are often not considered to have a sternpost.