Abstract: A manual trim tab for a power boat having a transom at the stern includes: a first bracket adapted to be mounted to the boat's transom near the surface of the water, the first bracket further having a first portion for mounting to the transom, a second portion extending downwardly from the first portion, and a third portion having a shelf, the shelf being substantially perpendicular to the first portion; a trim plate pivotally mounted on the first bracket by a lip pivotally engaging the shelf; a second bracket adapted to be mounted to the boat's transom above the first bracket; a lower adjustment rod pivotally mounted to the trim plate; an upper adjustment rod pivotally mounted to the second bracket and slidingly engaging the lower adjustment rod, thereby varying the angle at which the trim plate meets the watcr's surface; and a locking mechanism for preventing movement of the upper adjustment rod relative to the lower adjustment rod.