The sternpost is the upright piece at the back of a boat or ship.
The sternpost is an important part of a boat or ship.
Examples:
The sternpost helps the boat go straight.
The sternpost is at the back of the ship.
The captain fixed the sternpost.
The sternpost is like the boat's backbone.
The sternpost is as tall as a tree.
The sternpost is very important for the ship.