describes the condition of a ship when she is lying evenly in the fore and aft direction, i.e. when there is zero trim
The situation of a vessel when she is trimmed in such a way as to sit evenly on the water, with the keel parallel with the horizon.
The ship in a true vertical position as opposed to listing to the side
when a ship floats properly without any list. Also said to mean a situation is well in hand, everything in order. "He's got everything on an even keel."
A ship is said to be on an even keel when the keel is horizontal.
1. Floating level; 2. To have a relaxed, calm disposition
when the draft of a ship fore and aft are the same.