Trim is a term used to describe the angle of a boat in relation to the surface of the water. Trimming up or down causes the bow of a boat to rise or lower on the water. When travelling at high speed, the trim can also have an affect on the ride of a vessel, and with the right control can be used to maintain a comfortable and safe ride.

The trim will be different depending on the size of the vessel. Smaller boats are typically trimmed using power trim which adjusts the angle of the outdrive leg or outboard. Compared to larger boats with outdrives or shaft drives which commonly have trim tabs.

There are two ways which a boat can be trimmed, fore and aft. These involve raising and lowering the bow, if a trim tab is available then side to side leveling of the boat can be used if the boat begins to lean to one side.